1 Introduction
Catalysis constitutes a fundamental pillar of the modern chemical industry and energy systems， playing an indispensable role in energy conversion， chemical synthesis， and environmental remediation
[1-4]. From industrial-scale catalytic processes to mechanistic investigations conducted in laboratory settings， the efficiency， selectivity， and durability of catalytic systems are largely governed by the intrinsic properties of the catalysts employed
[5]. Researchers have developed diverse catalytic material systems with distinct structures. Noble metal catalysts such as Pt and Au have been reported to exhibit high activity in reactions including hydrogen evolution and CO oxidation
[6-7]. Metal oxides， including TiO
2 and ZnO， together with polymeric semiconductors like g-C
3N
4， have been extensively investigated in photocatalysis and environmental remediation
[8-10]. More recently， single-atom catalysts have attracted considerable attention owing to their maximized atomic utilization， demonstrating remarkable performance in reactions such as CO
2 reduction and oxygen reduction
[11-12]. These representative systems collectively highlight the crucial role of catalyst design in improving catalytic performance across diverse reaction processes.
However， catalyst design has long been constrained by the Sabatier principle and the associated linear scaling relationships derived from it. Within this theoretical framework， the adsorption energies of different reaction intermediates often exhibit strong linear correlations. Consequently， tuning the activation energy of one elementary step inevitably perturbs others， making it difficult to surpass the intrinsic performance limit described by the catalytic “volcano curve”
[13-14]. Meanwhile， the persistent trade-off among activity， stability， and selectivity remains a central challenge for practical catalyst development
[15-16]. In many cases， enhanced catalytic activity is accompanied by accelerated deactivation processes， such as sintering， carbon deposition， or active-site leaching， whereas strategies aimed at improving stability often lead to diminished catalytic reactivity
[17]. This challenge becomes particularly pronounced in reactions involving multi-step electron transfer or complex carbon-carbon coupling pathways， such as the carbon dioxide reduction reaction and methane conversion
[18-19]. In such systems， a single type of active site is typically insufficient to simultaneously satisfy the distinct kinetic requirements of multiple reaction steps
[20]. These limitations collectively highlight the urgent need for the development of new catalytic material systems.
For a considerable period， metallic alloy systems featuring disordered electronic structures and coordination framework materials possessing ordered topological structures （such as metal-organic frameworks and zeolites） have often been treated as two distinct research domains， lacking effective collaborative design approaches
[21]. These disconnects between research into electronic structure regulation and coordination structure design have significantly constrained the scope for material design that transcends conventional linear scaling relationships.
In recent years， the design concept of high-entropy materials has provided novel approaches to address this challenge. The high-entropy concept originates from high-entropy alloys （HEAs）， whose fundamental principle involves incorporating five or more metallic elements into a single lattice to form a single-phase solid solution， thereby generating a significant configurational entropy effect
[22-23]. It has been demonstrated that high configurational entropy has the capacity to stabilize multicomponent systems. Furthermore， owing to four core effects （high entropy effect， lattice distortion effect， slow diffusion effect， and cocktail effect）， high-entropy materials exhibit unique adsorption geometries and electronic configurations， which provide significant advantages for catalysis applications
[24-25]. This offers novel possibilities for regulating adsorption energies and reaction pathways in catalytic processes. Highly ordered porous crystalline materials （e.g.， metal-organic frameworks） offer well-defined pore architectures and isolated active sites， making them attractive catalyst platforms. These advantages have promoted researchers to explore the incorporation of high-entropy design strategies into such materials
[26-28].
Metal-organic frameworks （MOFs）， as a kind of periodic network structure porous material， have high specific surface area and regular pore structure， which is conducive to the high dispersion of active sites and the rapid transfer of reactants or products
[29-31]. Additionally， MOFs provide an ideal platform for integrating multiple metal components and achieving uniform atomic-scale distribution within a single lattice， owing to their highly designable metal nodes and organic ligand structures
[32-34]. Leveraging this structural advantage， researchers have progressively incorporated high-entropy design principles into MOF systems， leading to the development of high-entropy metal-organic frameworks （HE-MOFs） as an emerging material system. In contrast to conventional bimetallic or trimetallic MOFs， HE-MOFs attain near-proportional coexistence of multiple metal components within a solitary lattice node， thereby yielding a continuous and intricate distribution of metal centers. The coupling of electronic and geometric structures， induced by the coexistence of multiple metals， is a feature that low-entropy MOF systems struggle to achieve
[35-36]. Furthermore， when HE-MOFs undergo thermal or other treatments， the original organic components may be partially or fully removed， yielding derivatives such as high-entropy alloys， high-entropy metal oxides， high-entropy metal sulfides， or other metal-carbon composites. These derivatives further expand the diversity and application scope of HE-MOFs
[37-40]. Benefiting from tunable chemical functionality， abundant active metal sites， stable porous structures， and enhanced electrical conductivity， HE-MOFs and their derivatives have achieved remarkable progress in several catalytic and energy-related fields （
Fig.1）.
Against this backdrop， this review systematically examines the recent progress of HE-MOFs and their derivatives in catalytic applications. The fundamental definition and essential characteristics of HE-MOFs are first introduced， followed by a comprehensive overview of their primary synthetic strategies. In addition， recent developments in deriving HE-MOF-based functional materials via pyrolysis and calcination are discussed. From an application perspective， particular attention has been devoted to the utilization of HE-MOFs in electrocatalysis， thermal catalysis， and photocatalysis. In electrocatalysis， HE-MOFs have been explored for both oxidative and reductive transformations， including the oxygen evolution reaction （OER）， hydrogen evolution reaction （HER）， oxygen reduction reaction （ORR）， and nitrogen reduction reaction （NRR）. In thermal catalysis， these materials have demonstrated promising activity in a range of organic transformations， such as CO2 cycloaddition， transfer hydrogenation， alcohol oxidation， and amine-borane hydrolysis. In addition， emerging studies have begun to investigate HE-MOFs for photocatalytic applications， particularly in light-driven hydrogen production. The synergistic interactions among the multiple metallic components in high-entropy systems are highlighted， as they significantly enhance catalytic activity， selectivity， and stability， with unique electronic structures and surface properties serving as key contributors to catalytic performance. The review also delineates the principal challenges currently confronting the field， and outlines future directions aimed at guiding the rational design and development of advanced HE-MOF-based catalytic materials.
2 Definition and properties of HE-MOFs
Inspired by the HEA design philosophy
[41]， researchers have introduced this concept into the field of metal-organic frameworks， synthesizing high-entropy metal-organic frameworks （HE-MOFs）. In analogy to high-entropy alloys， the configurational entropy （Δ
Sconf） is commonly employed as a key criterion to define high-entropy systems. For a multi-component system， Δ
Sconf can be calculated based on the Boltzmann equation： Δ
Sconf = -
R×∑
xi×ln
xi， where
R is the gas constant and
xi represents the molar fraction of each component. For equimolar systems， this equation can be simplified to Δ
Sconf =
R×ln
N （
N is the number of components）. Generally， a system is considered to be a high-entropy material when Δ
Sconf≥1.5
R， which provides a useful guideline for the design and classification of HE-MOFs. HE-MOFs involve introducing multiple metallic elements at the same lattice site within a MOF， achieving random， uniform mixing at the atomic level
[42]. This multi-component disordered design endows the highly ordered MOF crystal structure with novel properties.
Firstly， as demonstrated by the Gibbs free energy equation Δ
Gmix = Δ
Hmix -
T ×Δ
Smix， elevated mixed entropy significantly reduces the Δ
Gmix of the system， thereby effectively suppressing the precipitation of intermediate phases. This enables HE-MOF to maintain outstanding catalytic stability even under harsh conditions such as high temperatures， high pressures， and strong corrosive environments
[43]. Secondly， within HE-MOFs， metallic elements with differing ionic radii coexist at the same lattice site， inducing lattice distortion effects. This microscopic lattice distortion and stress can significantly alter the local electronic structure and coordination environment around the metal centers， thereby creating favorable active sites for catalysis
[44]. Furthermore， due to lattice distortion effects， a substantial atomic migration potential barrier forms between the metallic elements within HE-MOF structures. This diffusion-limiting effect， arising from large atomic size differences， the coexistence of multiple elements， and complex crystalline structures， significantly constrains the diffusion kinetics of atoms within HE-MOF. Consequently， it effectively suppresses grain coarsening
[45]. Moreover， synergistic interactions among multiple elements can trigger a non-linear performance enhancement mechanism known as the “cocktail effect”. This concept， first systematically articulated by Ranganathan， denotes that through the judicious combination of multiple components， one can transcend the limitations of traditional linear superposition to achieve synergistic strengthening effects surpassing the theoretical expectations of any single component
[46].
Benefiting from these high-entropy characteristics and the intrinsic structural tunability of MOFs， HE-MOFs exhibit several unique advantages for catalysis. The multi-metal synergy introduced by the high-entropy effect can generate continuously tunable electronic structures， enabling effective regulation of the d-band center and adsorption energies of reaction intermediates， which offers a potential pathway to overcome the limitations imposed by traditional linear scaling relationships. Moreover， the atomically well-defined and uniformly distributed metal sites within the MOF lattice provide an ideal platform for establishing clear structure-activity relationships， addressing the long-standing challenge of surface heterogeneity commonly encountered in conventional high-entropy alloys. In addition， the confined pore environment of MOFs can facilitate cooperative interactions among multiple metal centers， promoting cascade reaction pathways and stabilizing key intermediates， thereby offering opportunities to break the traditional trade-off between catalytic activity and selectivity.
3 Synthesis of HE-MOFs and their derivatives
The synthesis of HE-MOFs and their derivatives is fundamental to achieving the desired entropy-driven structural features and， ultimately， high catalytic performance. Because the high-entropy state relies on the homogeneous incorporation of multiple metal species into a single crystalline lattice， the synthetic strategy plays a decisive role in determining the elemental distribution， defect structure， coordination environment， and thermal stability of the resulting materials. Over the past few years， a variety of synthetic routes have been developed to construct HE-MOFs with controlled compositions and architectures. These approaches range from conventional solvothermal and hydrothermal methods to emerging techniques such as solution-phase room-temperature synthesis， electrodeposition， and other rapid or continuous production routes. Broadly， these strategies can offer distinct advantages in regulating crystallization， compositional homogeneity， and defect structures. A comparative summary of these synthetic routes， including their key features， advantages， and limitations， is provided in
Table 1 to offer practical guidance for the rational design of HE-MOFs and their derivatives.
3.1 Synthesis of HE-MOFs materials
3.1.1 Thermodynamically driven solvothermal route
The solvothermal method is currently one of the most employed and effective strategies for synthesizing HE-MOFs. It typically involves a closed reaction system where multiple metal ions undergo coordination self-assembly reactions with organic ligands in organic solvents under low-temperature （< 200 ℃） and high-pressure conditions
[35]. Importantly， this approach effectively prevents phase separation between metals. Changes in solvent dielectric constant and diffusion behavior promote homogeneous mixing and coordinated incorporation of diverse metal ions， favoring the formation of genuine high-entropy architectures
[47-48]. Meanwhile， the relatively slow crystallization process improves framework crystallinity and structural integrity
[49].
For example， Xia et al.
[50] synthesized an HE-MOF by reacting equimolar amounts of metallic acetylacetonates （Fe， Co， Ni， Zn， Mo） with 2，6-naphthalenedicarboxylic acid tetrahydrate in a mixed solvent of water and ethanol via a solvothermal process. Such a controlled and prolonged crystal growth favored the uniform distribution of different metal species and the formation of a highly ordered framework， thereby suppressing phase separation that is commonly encountered in multimetal systems. The resulting HE-MOF exhibited a two-dimensional ultrathin nanosheet array structure with high crystallinity， and the thickness of a single nanosheet was merely 1.8 nm.
Building upon this controlled solvothermal crystallization， the cooling rate after the solvothermal reaction is another critical parameter governing the crystallinity and phase purity of HE-MOFs. As demonstrated by Qi et al.
[51]， a slower cooling process effectively suppresses the formation of mixed phases in multimetal MOF systems. When the solvothermal reactor was cooled at a reduced rate of 2 ℃/h rather than 5 ℃/h， a phase-pure HE-MOF single crystal with a well-defined layered structure was successfully obtained. This slow cooling process minimizes kinetic trapping and allows sufficient time for metal ions to redistribute and equilibrate within the framework， thereby promoting random yet homogeneous coordination of multiple metal species. Additionally， suitable solvents and auxiliary agents （such as triethylamine， polyvinylpyrrolidone， or chelating agents） can be selected based on the chemical properties of different metal ions to precisely control the multimetallic ratio and crystal morphology.
3.1.2 Electrochemically assisted electrodeposition strategy
Beyond the conventional solvothermal route， electrodeposition has recently emerged as an efficient and versatile strategy for constructing HE-MOFs. Under high overpotential conditions， the rapid deprotonation of ligands equalizes the coordination rates of different metal ions， thereby overcoming the intrinsic limitation of the solvothermal method in which metal ions with varied coordination abilities cannot react simultaneously
[52]. More importantly， during the electrodeposition process， the nucleation process of HE-MOFs is confined to the electrode surface， enabling rapid， spatially controlled growth and yielding films with tunable thickness， crystallinity， and morphology. Electrodeposition is widely employed to grow HE-MOFs directly on conductive substrates， typically yielding well-adhered thin films.
For example， Dong et al.
[53] successfully synthesized a defect-rich high-entropy zeolite imidazole framework （HE-ZIF） film on a nickel foam substrate via potentiostatic electrodeposition （
Fig. 2a）. In this work， a sufficiently high overpotential was deliberately applied during electrodeposition， which plays a decisive role in balancing the coordination kinetics of different metal ions. Under such a strong electrochemical driving force， the intrinsic differences in coordination affinity and reaction rates among individual metal species are largely suppressed. As a result， multiple metal ions are forced to participate simultaneously in the framework formation， enabling the construction of a single-phase high-entropy ZIF rather than phase-separated or metal-dominated structures.
Moreover， the metal salt concentration was found to exert a pronounced influence on the microscopic morphology of the electrodeposited HE-ZIF films. Dong et al.
[53] observed a clear concentration-dependent evolution of particle size and packing density. At relatively low metal ion concentrations， the HE-ZIF particles exhibit smaller sizes and a more compact arrangement， which can be attributed to a limited supply of metal species that favors high nucleation density while suppressing excessive crystal growth. In contrast， increasing the metal salt concentration leads to enlarged particle sizes and a more loosely packed structure， as the enhanced local availability of metal ions promotes crystal growth over nucleation.
Additionally， electrodeposition is not restricted to two-dimensional films； by regulating the applied potential， ligand deprotonation kinetics， and local concentration gradients， HE-MOFs can develop diverse surface-grown morphologies， including nanosheet arrays， granular domains， and polycrystalline layers. However， this approach cannot yield free-standing HE-MOF powders， as crystal growth is intrinsically confined to the electrode-electrolyte interface. Compared with solvothermal synthesis， electrodeposition offers mild operating conditions， low cost， rapid film formation， and precise control over film thickness and defect density. Notably， electrodeposited HE-MOFs generally exhibit low crystallinity and abundant structural defects， which substantially enhance their electrochemical activity， highlighting electrodeposition as a promising strategy for constructing defect-engineered HE-MOFs.
3.1.3 Kinetically controlled solution-phase method
The solution-phase method has also emerged as a facile and efficient route for the synthesis of HE-MOFs. Compared with the solvothermal method， this approach enables more effective mass transfer and homogeneous thermal distribution through magnetic stirring， thereby promoting uniform metal coordination
[42]. Furthermore， the method is compatible with a wide range of solvents and additives， offering flexible tuning of pH， ionic strength， and complexation equilibria to direct phase purity and crystallinity. Its operational simplicity， scalability， and low energy input make the solution-phase method particularly attractive for producing HE-MOFs in large quantities while preserving compositional homogeneity and structural integrity.
For instance， Zhao et al.
[42] successfully realized the rapid synthesis of an entropy-stabilized HE-MOF at room temperature by mixing Mn， Fe， Co， Ni， and Cu metal ions with 1，4-benzenedicarboxylic acid， while triethylamine was introduced as an acid-binding agent to initiate the coordination reaction. The continuous stirring during synthesis facilitated homogeneous dispersion and coordination among multiple metal ions， effectively avoiding the phase segregation typically observed in solvothermal reactions （
Fig. 2b）. More importantly， this method exhibits excellent scalability， enabling gram-level production （≈9 g per batch in a 2000 mL system） under ambient conditions （
Fig.2c）. The obtained HE-MOF features an ultrathin two-dimensional nanosheet morphology with near-equimolar metal distribution， high specific surface area， and superior dispersibility. The solution-phase approach not only overcomes the kinetic barriers associated with multimetal coordination but also provides an energy-efficient and easily scalable platform for the controlled synthesis of HE-MOFs with tunable morphology and composition.
3.1.4 Mechanical ball milling method
Mechanochemical ball milling has recently emerged as an attractive solid-state strategy for the synthesis of HE-MOFs. As a solvent-free or solvent-minimized technique， ball milling offers intrinsic advantages of green chemistry， high efficiency， and low energy consumption. Driven by mechanical force， metal precursors and organic linkers undergo direct solid-state reactions， effectively overcoming phase segregation caused by differences in metal hydrolysis or coordination kinetics. This facilitates homogeneous incorporation and solid-solution formation of multiple metal ions within the MOF lattice， making mechanochemistry a powerful route toward achieving high-entropy states.
For example， Wang et al.
[54] employed an entropy-driven mechanochemical approach to mill five metal salts （Co， Ni， W， Ru， and Mo） with terephthalic acid at room temperature， producing HE-MOF nanosheet precursors. The method accelerates the molecular diffusion of the material by inputting mechanical energy and frictional heat， which avoids long-term high-temperature heating and is conducive to the formation of HE-MOFs. The resulting material exhibited outstanding performance in the acidic hydrogen evolution reaction. Similarly， Ye et al.
[55] utilized a planetary ball mill to grind five metal sources-ZnO， MgO， Cu（OH）
2， Co（OAc）
2， and Ni（OAc）
2- with 2，5-dihydroxyterephthalic acid， directly yielding high-entropy MOF-74 （HE-MOF-74）. Characterization revealed atomically uniform metal distribution within the framework and a remarkable BET surface area of 1165 m
2/g， significantly higher than that of monometallic MOF-74 analogues. These successful demonstrations highlight that mechanochemical synthesis has become a valuable complement to conventional methods and represents a promising and scalable route for future industrial production of HE-MOFs.
The above synthetic strategies have significantly expanded the compositional and structural repertoire of HE-MOFs， laying a robust foundation for the development of their derivatives. Building upon this， researchers have in recent years further explored transforming HE-MOFs into derivative materials such as high-entropy oxides， alloys， phosphides， and sulphides through controlled pyrolysis or chemical conversion， thereby fully unlocking their potential for catalytic applications.
3.2 Synthesis of HE-MOFs derivatives
HE-MOFs not only serve as structurally ordered and compositionally tunable crystalline materials but also act as ideal precursors for generating high-entropy functional derivatives. During the derivation process， the atomic-level mixing of metal species is largely preserved or even enhanced by entropy stabilization， enabling the formation of single-phase multimetallic lattices or homogeneous nanocomposites. Moreover， the decomposition of organic linkers provides in-situ templating， porosity evolution， and sometimes carbonization， allowing the generation of hierarchical structures with high surface area， rich active sites， and defect-engineered interfaces. As a result， HE-MOF-derived materials have emerged as a powerful platform to leverage synergistic multimetal interactions for catalysis-related applications. In the following sections， we summarize the key thermal and chemical transformation strategies.
3.2.1 Pyrolysis method
Pyrolysis is one of the most widely employed strategies for producing high-entropy MOF-derived materials. In this method， HE-MOFs are heated under an inert or reducing atmosphere， during which the organic ligands thermally decompose while the metal centers undergo phase transformation， diffusion， and structural reconstruction， ultimately forming a high-entropy solid solution structure
[56]. This process yields a variety of high-entropy derivatives， including alloys and hybrid composites. Owing to the intrinsic features of HE-MOFs， such as uniform multimetal dispersion， well-defined architectures， and high specific surface areas， the pyrolysis process enables highly coupled nanoscale transformations， thereby offering distinct advantages for constructing entropy-stabilized materials.
For example， Wang et al.
[40] utilized a room-temperature-synthesized CoNiCuMnAl-MOF as a precursor and subjected it to pyrolysis at 700 ℃ under an Ar/H
2 reducing atmosphere. As illustrated in
Fig.3a， this treatment converted the organic ligands into ultrathin graphitic carbon shells while simultaneously reducing and alloying the uniformly distributed metal ions， ultimately forming face-centered cubic high-entropy alloy cores encapsulated within carbon layers （CoNiCuMnAl@C）. The resulting core-shell catalyst exhibited excellent electrocatalytic performance. In addition， if the phosphorus source is introduced during the pyrolysis process， the resulting sulfur-containing gas can react with the metal ions in the HE-MOFs to form high-entropy metal phosphides. For instance， Liu et al.
[57] employed sodium hypophosphite as a phosphorus source to phosphidize a five-metal HE-ZIF （Co， Ni， Mn， Cu， Fe） at 300~500 ℃ under Ar， producing high-entropy metal phosphides （N-C@CoNiMnCuFeP） coated with N-doped carbon and abundant phosphorus vacancies （
Fig.3b）. The obtained catalyst displayed superior activity and stability toward the oxygen evolution reaction， underscoring the strong potential of pyrolysis for the precise synthesis of multicomponent and multifunctional HE-MOF derivatives.
Despite these advantages， excessively high temperatures can lead to partial collapse of the intrinsic porosity and large surface area of MOF precursors
[58]. Moreover， the thermal decomposition of organic ligands is complex， making it challenging to precisely control the carbon shell thickness， degree of graphitization， and encapsulation behavior around alloy cores. Addressing these issues remains a key direction for future optimization of HE-MOF pyrolysis processes.
3.2.2 Air calcination method
Air calcination represents an effective strategy for directly converting HE-MOF precursors into high-entropy oxides and oxide-based composites. By controlling the heating rate， final temperature， and soak duration， air calcination achieves complete ligand removal， oxide crystallization， and the formation of multi-level pore structures， yielding oxide products with high specific surface areas and controllable morphologies.
For instance， Fereja et al.
[59] employed metal-organic frameworks as sacrificial templates to synthesize high-entropy oxides. A high-entropy MOF containing five metals （Fe， Ni， Co， Cr， and Cu） was first synthesized via a solvothermal method. This was subsequently calcined at 800 ℃ in an air atmosphere， converting it into a single-phase （FeNiCoCrCu）
3O
4 HEO structure （
Fig. 3c）. This approach effectively suppresses nanoparticle agglomeration at elevated temperatures， yielding HEO with a specific surface area as high as 206 m
2/g and abundant oxygen vacancies， thereby providing ample active sites for electrocatalytic reactions.
Additionally， Sarmila et al.
[38] constructed a high-entropy MOF precursor via the hydrothermal method and successfully prepared layered （MnCoNiCuZn）O high-entropy oxide through calcination in air （
Fig.3d）. Calcination at 900 ℃ in air enabled the uniform distribution of five transition metal ions at the atomic scale， resulting in a stable single-crystalline phase with high configurational entropy， which effectively suppressed secondary phase separation and enhanced the structural integrity and stability of the material. Meanwhile， the pores and structural defects generated during the pyrolysis of the HE-MOF provided abundant highly exposed active sites for the resulting HEO， significantly optimizing electron and ion transport and thereby improving mass transfer efficiency during the catalytic process.
3.2.3 Other methods
In addition， the ultra-rapid heating and cooling process in a very short time scale can create a highly non-equilibrium reaction environment， which enables the polymetallic components to achieve uniform solid solution， rapid diffusion and random occupation in a very short time
[60]. Compared with traditional pyrolysis or calcination processes， this ultrafast heat treatment technology effectively avoids issues such as grain growth and pore collapse caused by prolonged high temperatures. Consequently， it better preserves the structural characteristics of MOF precursors， ultimately yielding multi-metallic derivatives with uniform elemental distribution， structural stability， and high-entropy features.
For instance， Xie et al.
[61] recently proposed a super-rapid Joule heating strategy using MOF-derived carbon supports to fabricate PtFeCoNiMn five-element HEA. The method was based on the uniform loading of the multi-metal precursors onto the N-doped carbon derived from ZIF-8， and then the instantaneous heating was achieved by applying an electric current. The rapid thermal shock can promote the diffusion and mixing of the polymetallic atoms in a very short time， and form HEA with slight lattice distortion and homogeneous composition， and effectively inhibit the growth of the particles. Similarly， Yan et al.
[62] demonstrated that multivariate MOFs could be directly converted into single-phase high-entropy alloy nanoparticles via nanosecond pulsed laser irradiation， highlighting the general applicability of ultrafast thermal shock strategies for MOF-to-HEA transformation.
4 Electrocatalytic applications of HE-MOFs and their derivatives
HE-MOFs and their derivatives have recently emerged as a promising class of electrocatalytic materials. The unique “high entropy effect” enables the stabilization of multiple metal species within a single crystalline framework， giving rise to diverse yet synergistic active centers. In electrocatalytic reactions， the adsorption behavior of reaction intermediates is highly sensitive to applied potential and directly determines reaction kinetics and selectivity. Leveraging their complex and tunable electronic structures， HE-MOFs and their derivatives can effectively modulate the potential-dependent adsorption energy of reaction intermediates by controlling the local electric field and charge distribution at the electrode-electrolyte interface. This provides a multifunctional platform for optimizing reaction pathways and enhancing electrocatalytic performance
[63]. In the following sections， we will systematically summarize the latest research progress of HE-MOFs and their derivative materials in typical oxidation and reduction electrocatalytic reactions， with a focus on discussing the intrinsic relationship between representative reaction systems and their electrocatalytic performance and structure.
4.1 Electrochemical oxidation reactions
HE-MOFs and their derivatives demonstrate outstanding performance in various electrocatalytic oxidation reactions due to their multi-metal coordination effects and tunable electronic structures， particularly excelling in oxygen evolution reactions （OER）， a kinetically sluggish half-reaction in water splitting. The OER involves a four-electron transfer with multiple intermediates， including reactant diffusion， electron transfer， interfacial reaction， and oxygen release， and its overall performance is therefore strongly governed by mass transport and interfacial kinetics
[59]. In addition， the requirement of a four-electron transfer and multiple intermediate steps leads to intrinsically sluggish reaction kinetics. Conventional benchmark catalysts such as RuO
2 and IrO
2 deliver high activity but are limited by high cost and low abundance
[64]. In contrast， HE-MOFs， typically composed of multiple transition metals， have recently gained increasing attention for OER applications owing to their outstanding stability and catalytic activity.
The incorporation of multiple metal ions with disparate ionic radii into HE-MOFs often induces pronounced lattice distortions， disrupting the long-range crystallinity and generating abundant structural defects， such as vacancies and amorphous domains. These defect-rich structures can effectively modulate the electronic configuration and provide additional active sites， thereby enhancing catalytic performance
[65-66]. For example， Dong et al.
[53] successfully fabricated high-entropy ZIF （HE-ZIF） on a nickel foam substrate via an electrodeposition strategy. The resulting HE-ZIF consisted of low-crystallinity nanoparticles， as shown in
Fig. 4a and
4b. Vacancy defects and lattice distortions are observed in the crystalline domains， arising from the random distribution of metal atoms with different atomic radii. Benefiting from the characteristics of lattice distortion and defect enrichment induced by high entropy， the as-prepared HE-ZIF exhibited excellent OER activity， requiring an overpotential of only 290 mV to achieve a current density of 100 mA/cm
2， and demonstrated remarkable durability after 100 h of continuous operation in 1 mol/L KOH.
It should be noted that all synthesized HE-ZIFs consist of small nanoparticles prone to aggregation， forming larger irregular spherical particles with numerous voids. While the authors proposed that these voids enhance active sites， particle aggregation reduces the effective active surface area and may even obstruct the inherent pore structure of HE-MOFs， thereby impeding mass transfer
[67]. This limitation underscores the importance of engineering aggregation-resistant architectures with accessible pore networks.
The two-dimensional （2D） HE-MOF nanosheets are an effective strategy to suppress nanoparticle aggregation. Moreover， the 2D HE-MOF arrays form a unique porous layered structure， which provides an efficient transport channel for electrons and reaction intermediates， thus enhancing catalytic activity.
For example， Xu et al.
[28] employed a mild solvothermal strategy using 2，6-naphthalenedicarboxylic acid tetrahydrate as the organic linker for in situ growth of 2D HE-MOF arrays on NF substrates （
Fig.4d）. Atomic force microscopy （AFM，
Fig.4c） images confirmed the ultra-thin structure of the HE-MOF， with a thickness of only 1.8 nm. This morphology effectively suppressed nanoparticle restacking and generated hierarchical porosity， including tens-of-nanometer interlayer mesopores and the intrinsic micropores of the MOFs， which collectively facilitated the transport of reactants， intermediates， and gas bubbles. The electrochemical impedance spectroscopy （
Fig.4e） confirmed that HE-MOF exhibited charge transfer impedance superior to other MOFs with low metal content and IrO
2. Electrochemical measurements demonstrated that the catalyst exhibited excellent OER performance， requiring an overpotential of only 254 mV to deliver 50 mA/cm
2 （
Fig.4f）， and exhibited the smallest Tafel curve （61 mV/dec）， indicating that HE-MOF facilitated the optimal kinetics of the oxygen evolution reaction （
Fig.4g）. These results highlight that the enhanced OER performance of 2D HE-MOFs is not only associated with their structural advantages， but also arises from the synergistic interaction of multiple metal centers， which enables optimized adsorption of oxygen-containing intermediates and improved reaction kinetics.
In general research， the authors always emphasized that five different metals are uniformly dispersed in the prepared HE-MOF， and the atom fraction of each metal is 5% to 35%
[68]. This design philosophy is consistent with the widely accepted concept of high-entropy materials
[69]. According to the ideal mixing model， when the number of components increases and the proportion of each component tends to be uniform， the configuration entropy of the system reaches a high level， so the “five components and above” has long been regarded as an empirical criterion for the formation of a high-entropy structure.
Recent studies indicate that the high-entropy effect is not strictly limited to systems containing five or more metals. When multiple components achieve a homogeneous solid-solution state with random lattice occupation， quaternary systems can still deliver sufficient configurational entropy to stabilize a single-phase structure. For example， Jiang et al.
[70] synthesized a tetra-metal HE-MOF （HE-DOBPDC） via a one-pot hydrothermal method using Fe， Co， Ni and Mn nodes. The petal-like architecture composed of nanorod clusters provides abundant exposed active sites and facilitates electrolyte accessibility. Elemental mapping confirmed the uniform and near-equimolar distribution of all metal species without phase segregation， while XRD patterns revealed a well-defined single-phase framework with slight peak shifts induced by lattice distortion， evidencing typical high-entropy characteristics. Notably， the configurational entropy of the equimolar quaternary system （Δ
Sconfig ≈1.39
R） is only ~14% lower than that of a five-component system， remaining within the high-entropy regime. Benefiting from the multimetal synergy， HE-DOBPDC exhibited excellent OER activity， requiring an overpotential of only 298 mV to reach 50 mA/cm
2， outperforming most monometallic MOF counterparts.
In addition， equimolar multimetal combinations were widely employed to maximize configurational entropy in HE-MOFs. However， recent findings indicate that as long as multiple metals can be highly dispersed and randomly occupy the framework nodes， non-equimolar “composition-biased” systems can still retain pronounced high-entropy characteristics. More importantly， this non-equimolar high-entropy strategy provides additional degrees of freedom for performance tuning， enabling researchers to precisely optimize electronic structure， active site distribution， and reaction pathways by adjusting specific metal ratios while maintaining the structural stability conferred by the high-entropy effect.
For example， the Co-rich HE-MOF reported by Yao et al.
[44] remained a high-entropy material because five transition metals jointly constructed the nodes and preserved random occupation despite the compositional bias toward Co. XPS analysis revealed that， compared to the single-metal Co-TDC-BIPY， the O 1s spectra of high-entropy MOFs （such as EMC-HEMOFs and Co-rich HEMOFs） exhibited broad peaks and distinct low-oxygen coordination， indicating altered oxygen electronic structures. Additionally， the increased Co 2p binding energy confirmed the formation of high-valent cobalt and localized electronic structure modulation. These electronic structure changes optimize the adsorption energy of oxygen intermediates （
*OH，
*O，
*OOH） at the active site， bringing it closer to the ideal value. Consequently， the energy barriers for the conversion of
*OH to
*O and
*O to
*OOH during the OER process are reduced， thereby enhancing the reaction kinetics. Electrochemical tests indicated that the Co-rich HE-MOF delivers outstanding OER performance， requiring only 310 mV overpotential at 10 mA/cm
2. The works by Jiang et al. provide crucial insights into the high-entropy effect and offer a practical approach for the rational design and performance optimization of high-entropy MOFs.
Building upon the composition-biased strategy， recent studies have further extended the high-entropy concept to hydroxide-based metal-organic frameworks （HE-MHOFs）. This structural evolution is motivated by the intrinsic limitations of conventional HE-MOFs in OER， where the relatively weak M-O-C coordination and limited electrical conductivity may restrict charge transfer and structural robustness under highly oxidative conditions. By incorporating metal hydroxide into the framework， HE-MHOFs combine the high stability and fast redox kinetics of metal hydroxides with the structural tunability and porosity of MOFs. Such a hybrid coordination environment not only preserves the high-entropy solid-solution effect but also strengthens metal-oxygen bonding and electronic coupling， thereby providing a more favorable OER catalysis.
In the HE-MHOF system constructed by Roy et al.
[71]， multiple transition metals （Mn， Co， Ni， Cu， Zn） are randomly and uniformly distributed within a two-dimensional high-entropy hydroxide layer. These metals are interconnected via organic ligands to form a stable three-dimensional framework， effectively avoiding the phase separation issues commonly observed in multi-metal systems. Notably， as shown in
Fig.5a， mechanistic analyses based on operando XAS and DFT calculations reveal that the HE-MHOF surface exhibits both adsorbate evolution mechanisms （AEM） and intramolecular O—O coupling pathways （IMOC）. In high-entropy environments， different metal sites demonstrate synergistic roles： Mn and Co sites favor
*O—
*O coupling processes， while Ni sites are more conducive to
*OOH formation and transformation， thereby significantly lowering the energy barrier of the rate-determining step in OER. This multi-path synergistic mechanism driven by the high-entropy effect enables HE-MHOF to achieve superior oxygen evolution activity and durability compared to single-metal MHOF and noble metal catalysts， while maintaining long-term structural stability.
Moreover， the HE-MOFs offer stable sites for atomic-scale metals and regulate the local electronic structure through multi-metal electronic coupling， thereby simultaneously enhancing the dispersion and reactivity of the metal sites. For instance， Mu et al.
[45] reported the ultrathin amorphous HE-MOF-stabilized Ru（Mo） dual-atom catalyst. The disordered coordination environment and high defect density within HE-MOF effectively suppress the migration and agglomeration of dual-atom sites. As shown in
Fig.5b， the formation of oxygen vacancies establishes unsaturated metal sites， thereby effectively modulating the electronic structure of active sites. Furthermore， as additional active sites， surface oxygen vacancies can significantly enhance the charge transfer capability of semiconductor electrocatalysts. These combined structural and electronic effects yield superior intrinsic OER activity and durability compared with low-entropy analogues （
Fig.5c）， underscoring the pivotal role of HE-MOFs as efficient supports for atomic-scale metal sites.
In addition to the structural advantages as a support
[72]， the homogeneous solid solution and thermodynamic reconfigurability of HE-MOF enable it to be directly transformed into various derivatives during heat treatment， such as high-entropy oxides （HEO）， high-entropy alloys （HEA）， high-entropy phosphides （HEP）， and high-entropy sulfides （HES）. The thermal behavior of polymetal under high temperature and solid phase is often different， which may lead to unpredictable decomposition， secondary phase formation or structural collapse， thus weakening the stability and activity of HEO. The MOF-assisted strategy releases a large number of gas molecules from the ligands and solvents during pyrolysis， spontaneously forming a highly porous architecture between particles. This not only suppresses particle coarsening caused by high-temperature sintering but also introduces abundant defects and exposed sites in the final HEO， enabling it to maintain excellent reaction kinetics even under high current density
[38].
In this context， Miao et al.
[73] successfully fabricated ZnFeNiCuCoRu-O HEO with polyhedral morphology and hollow structure through a synergistic approach combining ion exchange and HE-MOF templating. Prior to thermal oxidation， the ZnFeNiCuCo precursor exhibited a typical polyhedral solid structure. Due to the moderate ion exchange kinetics between Ru
3+ and the pre-existing metal ions in the MOF， Ru could be uniformly embedded into the framework to form a stable multimetallic precursor. This transformation resulted in the solid polyhedron converting into a hollow structure after 4 hours of air annealing （
Fig.5d）. As shown in
Fig.5e， the modified material exhibits excellent OER catalytic activity and cyclic stability. This study demonstrates that strategically designing the composition and ion-exchange sequence of MOF-based precursors can significantly enhance the structural controllability and element compatibility of hollow HEOs， further highlighting the unique advantages of MOF platforms in structurally controlled high-entropy oxides.
In addition， if the reduction conditions are introduced during the pyrolysis process to completely convert the polymetallic precursors into metallic states， another class of materials based on the high-entropy effect， HEAs， can be constructed. Compared to HEO， HEA exhibits superior metal conductivity， a richer array of surface metal sites， and more flexible electronic structure modulation， giving it distinct advantages in multiphase catalytic reactions. For instance， Huang et al.
[37] conducted pyrolysis of HE-MOF precursors in an H
2/Ar mixed atmosphere under controlled temperature and time， producing easily deformable single-phase face-centered cubic HEA nanoparticles （MnFeCoNiCu） with sizes below 5 nm. Field emission scanning electron microscopy revealed the morphology of the five-membered MOF precursor， where the carbon cloth appears uniformly coated with high-density nanoparticles across its entire surface （
Fig.5f）. This uniform coverage results from the decomposition of the HE-MOFs during the pyrolysis process. Furthermore， the atomic lattice TEM image revealed numerous dislocations， including partial dislocations and stacking faults. When these defects are formed in such a small nanoparticle， it will lead to significant deformation and produce a large surface tension， which is conducive to reducing the electron transfer resistance （
Fig.5g）， thus exhibiting excellent reaction kinetics performance （
Fig.5h）. This enhancement markedly improves their OER catalytic performance.
Typically， the OER involves two competing pathways： the adsorbate release mechanism （AEM） and the lattice oxygen-mediated mechanism （LOM）. The AEM， constrained by the Sabatier principle and linear scaling relationship， exhibits a theoretical minimum overpotential of approximately 370 mV even for optimal materials
[74]. The LOM suffers from lattice oxygen loss， which leads to structural instability of the catalyst
[75]. In single-component or single-active-center systems， achieving an effective balance between the upper limit of activity in AEM and the structural stability of LOM is often challenging. Recent studies demonstrated that the high-entropy effect-induced random site occupancy and diversified active centers not only broaden the adsorption energy distribution of reaction intermediates， thereby partially alleviating the linear scaling limitation imposed on AEM， but also enable controlled lattice oxygen participation at specific sites to promote LOM formation. Concurrently， the configurational entropy stabilization effect derived from multi-element synergy helps suppress irreversible lattice oxygen loss and structural collapse， achieving synergistic activation of AEM and LOM while establishing a new equilibrium between high activity and long-term stability.
Using MoZnFeCoNi metal-organic frameworks as precursors， Mei et al.
[76] fabricated five metal elements into homogeneous and stable single-phase HEAs through ultrafast thermal shock treatment. This short-duration process effectively prevented molybdenum reaction and zinc volatilization. The ligand coordination during alloying significantly suppressed zinc's rapid volatilization， ultimately forming a hierarchical porous structure with a 3D interconnected carbon skeleton （
Fig. 6a）. DFT calculations showed that the overpotential of AEM and LOM on the MoZnFeCoNiOOH formed by surface reconstruction of the catalyst is very close and both are very low （0.438 eV vs. 0.430 eV）， which proves that the two paths are thermodynamically feasible. Specifically， Mo optimized the Co-Co
†-Mo site， significantly lowering the AEM energy barrier and promoting
*OH deprotonation. Meanwhile， Zn formed the Zn-O
†-Ni site， weakening the M—O bond to activate lattice oxygen and efficiently trigger LOM. As shown in
Fig. 6b and
6c， this resulted in an ultra-low OER overpotential （221 mV） and achieved long-term catalytic performance， stabilizing operation for over 800 h at 500 mA/cm
2 current density.
Furthermore， the incorporation of phosphorus （P） during thermal reduction facilitates the reaction between sulfur-containing gases and HE-MOF metal nodes， forming metal sulfides. Simultaneously， P introduces modifications to the transition metal d-band structure， enhancing conductivity compared to oxides and thereby exhibiting superior electrocatalytic performance
[77-78]. For instance， Li et al.
[79] used HE-MOF as a template， they subsequently fabricated a high-entropy phosphide/carbon composite （FeCoNiCuYP/C） in an Ar/PH
3 atmosphere （
Fig.6d）. The material exhibited a uniform wrinkled morphology and amorphous structure. Theoretical calculations and experimental results demonstrated that the incorporation of Fe， Co， and Ni elements can effectively modulate the electronic structure of FeCoNiCuYP， optimizing the binding strength of metal-P bonds. The Fe sites preferentially adsorbed and stabilized HO
* intermediates， promoting the adsorption and deprotonation of OH
-， while the Co/Ni sites favored the stabilization of HOO
* intermediates， facilitating the formation of O—O bonds. This site-specific cooperative mechanism disrupts the traditional energy scaling relationship between HO and HOO in OER， thereby lowering the reaction energy barrier. As a result， the FeCoNiCuYP/C electrocatalyst demonstrated outstanding performance in oxygen evolution reaction， achieving a current density of 100 mA/cm
2 with only 316 mV overpotential under alkaline conditions.
Furthermore， Li et al.
[80] successfully synthesized nanoscale HEMS through direct solvothermal sulfidation of HE-MOFs. The research demonstrated that the ultra-fine nanoparticles （3 nm） distributed within the MOF framework provided multiple surface active sites， substantially enhancing electron transfer efficiency. XPS analysis revealed reduced electron density in Fe and Cu after sulfidation， while Co and Ni exhibited electron-rich states， creating a synergistic electron effect. The residual SO
42- on the sulfurized surface may further promote oxygen evolution reaction （OER） activity. In OER performance tests， HEMS exhibited outstanding activity， achieving a current density of 10 mA/cm
2 with an ultra-low overpotential of 221 mV. These combined advantages enable superior activity， durability， and reaction versatility compared with single-metal or low-entropy counterparts. The catalytic reactivity of HE-MOFs and HE-MOF-derived materials is summarized in
Table 2.4.2 Electrochemical reduction reactions
Compared with the extensively studied OER， investigations of HE-MOFs in electrochemical reduction reactions such as the hydrogen evolution reaction （HER）， oxygen reduction reaction （ORR）， and nitrogen reduction reaction （NRR） remain relatively limited. Nevertheless， emerging studies have demonstrated their promising potential in tuning reaction pathways and improving catalytic performance. These reduction reactions typically involve complex proton-electron coupling steps and multi-intermediate pathways， making them highly sensitive to the electronic structure and active-site distribution of catalysts. As a result， they play crucial roles in sustainable energy conversion， environmental remediation， and green chemical synthesis.
4.2.1 Hydrogen evolution reaction
Depending on the electrolyte environment， the hydrogen evolution reaction （HER） proceeds through distinct reaction pathways， typically described by the Volmer， Heyrovsky， or Tafel steps， in which the adsorption and desorption of hydrogen intermediates （H
*） play a decisive role in determining reaction kinetics
[82]. Although noble-metal catalysts such as Pt exhibit near-optimal hydrogen adsorption free energy （Δ
G{H*}）， their high cost and limited abundance significantly hinder large-scale applications
[83]. In this context， HE-MOFs and their derivatives have attracted increasing attention as promising HER electrocatalysts， owing to their multi-metal synergistic effects， tunable electronic structures， and highly dispersed active sites， which collectively enable precise regulation of hydrogen adsorption energetics and reaction pathways.
For instance， Wang et al.
[54] synthesized HE-MOF nanosheets via mechanochemical methods at room temperature， followed by high-temperature phosphating to obtain entropy phosphate/carbon （HEP
i/C） hybrid nanosheets with a thickness of approximately 22 nm （
Fig.7a）. Electrochemical impedance spectroscopy revealed that HEP
i/C hybrid nanosheets exhibited lower charge transfer resistance， indicating enhanced interfacial interactions that facilitate rapid charge transfer between the catalyst and reactants. Furthermore， HEP
i/C nanosheets inherit the high surface area characteristic of HE-MOF nanosheets， providing additional catalytic active sites for the reaction. The HEP
i/C hybrid nanosheets exhibited outstanding HER performance in 0.5 mol/L sulfuric acid solution， with an overpotential of 40 mV at 10 mA/cm
2 current density， outperforming commercial Pt/C catalysts. Notably， the HER polarization curves showed no significant changes after 5000 cycles， demonstrating excellent stability due to their stable high-entropy structure.
4.2.2 Oxygen reduction reaction
Oxygen reduction reaction （ORR） is recognized as one of the most critical electrochemical reduction reactions in energy conversion and storage， holding significant research value in fuel cells， metal-air batteries， and renewable energy storage. However， the highly stable O $\stackrel{\mathrm{ }\mathrm{ }\mathrm{ }\mathrm{ }}{̿}$O double bond in O2 makes its cleavage and reduction processes involve complex multi-step electron-proton transfers， posing substantial challenges in both thermodynamics and kinetics. In recent years， HE-MOFs and their derivatives have demonstrated remarkable potential for the development of efficient and durable non-noble-metal ORR catalysts.
For instance， Liang et al.
[84] successfully synthesized small-sized PtPdNiCoV， PtPdNiCoZn， and PtPdNiCoFe nanoparticles by pyrolyzing nitrogen-doped porous carbon derived from ZIF-8， which were subsequently applied in ORR. The spatial confinement effect of MOF-derived carbon carriers resulted in nanoparticles with a uniform size distribution. XPS analysis revealed a rich valence state distribution and abundant low-coordination atoms on the material surface， providing ample high-activity sites. As shown in
Fig.7b， the ORR mass activity of the three nanoparticles significantly outperforms commercial Pt/C catalysts （0.14 A/mg （Pt））， with PtPdNiCoZn achieving 0.39 A/mg （Pt）， PtPdNiCoV 0.19 A/mg （Pt）， and PtPdNiCoFe 0.18 A/mg （Pt）. Koutecky-Levich analysis further confirms that the ORR on these high-entropy alloys primarily occurs via the four-electron pathway， indicating that the reaction predominantly produces water. Furthermore， the research team activated the catalyst through approximately 100000 cyclic voltammetry scans， inducing surface restructuring that significantly enhanced catalytic activity. The reconstructed nanoparticles maintained stable size and distribution， a result attributable to both the inherent stability of the high-entropy alloy and the protective effect of the carbon-based support.
In addition to noble-metal-based high-alloy systems， hollow high-entropy MOF-derived nanocomposites composed of transition metals have also demonstrated promising ORR activity. For example， Hu et al.
[85] reported a porous hollow high-entropy MOF-74 incorporating six metal elements （Mn， Fe， Co， Ni， Cu， and Zn） as precursors to construct a multi-component nanocomposite via pyrolysis. The obtained material consisted of metal nanoparticles （Mn， Fe/Ni， Co， Cu）， metal alloys （Cu—Ni and Co—Cu）， and ZnO， forming a unique metal/metal-alloy/metal-oxide hybrid structure. Benefiting from the synergistic interaction among multiple high-entropy components and the hollow architecture with abundant internal channels， the optimized catalyst （annealed at 650 ℃） exhibited an onset potential of 0.97 V and a half-wave potential of 0.79 V in alkaline media. Koutecky-Levich analysis indicated a near four-electron transfer pathway （
n ≈ 3.7）， confirming its high selectivity toward water formation. The enhanced activity was attributed to the high-entropy effect-induced electronic modulation， improved conductivity from in situ-formed alloys， and facilitated mass transport enabled by the hollow porous structure.
4.2.3 Nitrogen reduction reaction
The nitrogen reduction reaction （NRR） still faces significant challenges. On one hand， the extremely high bond energy of the N≡N triple bond （941 kJ/mol） results in slow reaction kinetics
[86-88]. On the other hand， NRR requires a multi-electron/proton coupling transfer process （6e
-/6H
+）， making it highly susceptible to competitive inhibition by HER
[89]. This imposes higher demands on the electronic structure of the active site and the regulation of the reaction interface. In this regard， HE-MOFs offer a promising platform for NRR catalysis， as their diverse multi-metal coordination environments and highly tunable local electronic structures enable effective activation of N
2 molecules while suppressing the competing HER.
Sun et al.
[90] reported a HE-MOF based on Ni-Co-Fe-Zn-V multimetallate nodes， which was acid-treated to investigate its catalytic behavior in electrochemical N
2 fixation. This work demonstrated that the high solid solution and random distribution of multiple transition metals within the same MOF node significantly increased the system's configurational entropy， inducing notable lattice distortion and electronic structure rearrangement （
Fig.7c and
7d）. This high-entropy effect not only expanded the number of potential N
2 adsorption and activation sites but also optimized the adsorption strength of key reaction intermediates （such as N
2 and NNH） through electronic interactions among the metals. Under acidic conditions， the acid-treated HE-MOF achieved a maximum NH
3 generation rate of approximately 51.35 μg/（h·mg） （
Fig.7e）， significantly outperforming corresponding single-metal or low-component MOF catalysts.
4.2.4 Other reactions
Notably， the cycloaddition reaction between CO
2 and epoxides to form cyclic carbonates has garnered significant attention in recent years due to its 100% atomic utilization rate， environmental friendliness， and industrial application potential. However， CO
2 molecules exhibit high thermodynamic stability， and the reaction still requires efficient catalysts to achieve efficient conversion under mild conditions
[91]. By incorporating multiple metal elements， HE-MOFs amplify the synergistic effects of multi-active sites， providing novel material design strategies for efficient CO
2 fixation and conversion.
Ye et al.
[55] successfully synthesized a high-entropy MOF-74 （HE-MOF-74） with a uniform distribution of five metal ions （Zn， Mg， Ni， Co， and Cu） using a simple and efficient mechanochemical ball milling method. The abundant unsaturated metal centers in HE-MOF-74 provide multiple Lewis acid sites for epoxide activation， while the oxygen atoms of the metal ligands and hydroxyl groups function as basic sites to synergistically enhance CO
2 adsorption and insertion. The coordinated action of multiple metal elements within the framework not only increases the local CO
2 concentration in the pores but also effectively lowers the reaction energy barrier， thereby significantly improving the overall efficiency of CO
2 cycloaddition reactions. Performance test results demonstrated that HE-MOF-74 exhibited significantly higher specific surface area and CO
2 adsorption capacity compared to its single-metal counterpart， MOF-74. In the cycloaddition reaction of CO
2 and propylene oxide， HE-MOF-74 demonstrated outstanding catalytic performance： at 100 ℃， the propylene carbonate yield reached 91.6%， markedly outperforming the single-metal reference catalyst （
Fig.7f）. Furthermore， the catalyst maintained a high yield of approximately 90% and a stable structure throughout five consecutive cyclic reactions （
Fig.7g）， demonstrating excellent chemical stability and reusability.
HE-MOFs and their derivatives have demonstrated broad applicability and significant performance advantages in various electrocatalytic reactions. The entropy-stabilized solid solution of multiple metal nodes generates locally distorted coordination environments and a broadened electronic structure distribution， leading to diversified active sites with tunable adsorption energetics. Such multi-metal synergism enables optimized binding of key intermediates （e.g.， H*， O*， OOH*， N2*， and CO2*）， while selectively suppressing competing reactions such as hydrogen evolution in NRR and CO2RR or the two-electron pathway in ORR， thereby improving both catalytic kinetics and product selectivity. Furthermore， HE-MOFs exhibit controllable structural evolution under reaction conditions， forming high-entropy oxides， high-entropy alloys， or other defect-enriched derivative phases. This enables them to demonstrate remarkable structural adaptability and catalytic robustness across diverse reaction environments.
Notably， in CO2 conversion reactions， HE-MOFs achieve efficient CO2 adsorption， activation， and synergistic conversion by integrating Lewis acid/base sites and multi-metal active centers， highlighting the unique potential of HE-MOF-derived catalysts for carbon resource utilization. HE-MOFs and their derivatives are not only high-performance catalytic materials but also provide a design paradigm for catalysts based on high-entropy regulation. By strategically selecting metal components， optimizing composition ratios， and inducing structural reconfiguration， the HE-MOF platform offers crucial insights for developing efficient and stable catalysts for multi-reactive systems. Furthermore， it lays a solid foundation for advancing multifunctional electrocatalysis and carbon-neutral transformation technologies in the future.
5 Thermocatalytic applications of HE-MOFs and their derivatives
Thermal catalysis serves as the backbone of modern chemical engineering， underpinning critical processes ranging from carbon fixation to pollutant remediation. Unlike electrocatalysis， which is driven by applied potential， thermal catalysis relies heavily on the intrinsic surface energy， defect chemistry， and thermal stability of the material to lower activation barriers. Traditional catalysts， such as single-atom metals or binary oxides， often face insurmountable trade-offs between activity and stability， particularly suffering from sintering and phase segregation at elevated temperatures. MOFs， despite their remarkable structural tunability and exceptionally high surface areas already discussed， have historically faced important limitations related to thermal and chemical stability under catalytic conditions
[92-93]. In fact， the limitations associated with thermal stability have been one of the most extensively studied issues in the field of MOFs. Under moderately high temperatures， many MOF structures can undergo framework collapse， ligand decomposition， or partial amorphization， especially when exposed to reactive atmospheres containing water vapor， oxygen， or reducing gases.
As a consequence， the structural integrity of the porous framework and the accessibility of active sites can be compromised during catalytic operation. Even relatively robust families， such as Zr-based or Cr-based MOFs， may experience structural degradation or gradual loss of crystallinity when subjected to prolonged thermal treatments or harsh reaction environments
[94-95]. These stability challenges are expected to remain relevant in high-entropy MOF systems， where the incorporation of multiple metal centers can introduce additional structural complexity and potential heterogeneity within the framework.
HE-MOFs and their derivatives address these challenges through a paradigm shift in material design. The “entropy stabilization effect” significantly hinders atomic diffusion， thereby preventing the agglomeration of active sites， while the “cocktail effect” allows for the integration of multi-functional active centers （e.g.， Lewis acid-base pairs or redox couples） within a single lattice. Currently， research in this domain advances along two complementary trajectories： utilizing the pristine HE-MOF framework for mild liquid-phase reactions to leverage its tailorable pore environment， or employing the MOF as a sacrificial precursor to generate HEOs and HEAs with superior thermal durability.
5.1 CO2 cycloaddition
While the cycloaddition of CO
2 with epoxides is a promising 100% atom-economic strategy for carbon fixation， its rate-determining step-epoxide ring-opening-demands robust Lewis acidity， alongside efficient nucleophilic attack to activate the inert CO
2[96-97]. Conventional mono- or bimetallic MOFs inherently lack the compositional diversity to furnish a sufficient density of such cooperative active sites. Integrating the “high-entropy” concept into MOFs elegantly resolves this bottleneck. HE-MOFs confer unprecedented advantages in this catalytic domain by dictating reaction pathways through two distinct physicochemical dimensions： geometric/structural optimization driven by lattice distortion， and synergistic active-site modulation stemming from the multielement cocktail effect.
At the structural level， incorporating multiple principal elements with varying ionic radii inevitably induces local lattice distortion within the HE-MOF framework， thereby optimizing the density and accessibility of exposed active sites. A quintessential example was recently demonstrated by Ye et al.
[98]， who synthesized an amino-functionalized high-entropy lanthanide MOF （HE-LnMOF） comprising five near-equimolar lanthanide ions （Eu
3+， Tb
3+， Gd
3+， Dy
3+， Ho
3+） and 2-aminoterephthalic acid. The intrinsic ionic radius mismatch， exacerbated by lanthanide contraction， created a highly distorted framework， endowing the HE-LnMOF with an enlarged specific surface area and enriched active sites compared to monometallic counterparts. In-situ DRIFTS analyses explicitly elucidated a spatially synergistic dual-activation pathway： the uncoordinated amino groups （—NH
2） act as Lewis bases to capture and polarize CO
2 （
Fig. 8a）， while the structurally distorted high-entropy lanthanide clusters serve as robust Lewis acidic centers to activate the epoxide oxygen （
Fig.8b）. Assisted by the nucleophilic attack of bromide ions from the co-catalyst， this geometrically optimized HE-LnMOF delivered an exceptional propylene carbonate yield of 94.8% （120 ℃， 1.2 MPa）， vastly outperforming single-metal analogues and exhibiting good stability over multiple cycles.
vBeyond structural strain， the “cocktail effect” in HE-MOFs compels multiple diverse metal nodes into a single lattice， creating unprecedented synergistic catalytic microenvironments. For instance， Xu et al.
[99] successfully incorporated five transition metals （Zn
2+， Co
2+， Cd
2+， Ni
2+， and Cu
2+） into a single-phase zeolite imidazole framework （HE-ZIF） via a rapid mechanochemical approach （
Fig.8c）. Rather than focusing on structural features， this work vividly demonstrates how the multielement cocktail effect fundamentally modulates intrinsic catalytic activity. For the cycloaddition of CO
2 with halogenated epoxides， the random distribution of these five distinct metal species creates a complex， highly hybridized electronic environment. This synergistic multimetallic network acts as an exceptionally potent Lewis acid to aggressively activate the epoxide， effectively complementing the basic nitrogen moieties of the imidazole linkers. Consequently， under mild conditions （100 ℃， 10 bar CO
2 （1 bar=100 kPa））， the HE-ZIF achieved a remarkable 99.0% yield， a performance exponentially superior to that of individual single-metal ZIFs （e.g.， ZIF-8， 42.8%） or their physical mixtures （
Fig.8d）. This breakthrough validates that the high-entropy cocktail effect constructs a superior synergistic environment， optimizing Lewis acidity for substrate activation far beyond the simple linear combination of its constituent elements.
5.2 Catalytic transfer hydrogenation
Catalytic transfer hydrogenation （CTH）， employing organic alcohols as hydrogen donors via the Meerwein-Ponndorf-Verley （MPV） mechanism， offers a safer and more sustainable alternative to high-pressure H
2. Kinetically， efficient CTH requires precise microenvironmental orchestration to simultaneously activate the hydrogen donor and the target carbonyl substrate
[100-101]. However， conventional catalysts face critical bottlenecks： attempting to increase the density of active sites often destabilizes the pristine framework， while achieving strong electronic synergy typically demands harsh operating conditions. HE-MOFs and their derivatives elegantly circumvent these limitations， driving CTH efficiency through two distinct paradigms： entropy-driven structural defect engineering and cocktail-effect-induced interfacial charge redistribution.
Addressing the fundamental trade-off between active-site density and framework stability， Ma et al.
[102] surmounted the thermodynamic limits of defect generation by deploying an “entropy engineering” strategy to construct a high-valence HE-UiO-66 framework （Zr， Hf， Ce， Sn， Ti）. Elevated configurational entropy significantly increased the lattice tolerance to severe distortion， safely accommodating massive missing-linker defects without structural collapse， while leveraging the sluggish diffusion effect to constrain the particle size to ~32 nm. Crucially， this extreme structural perturbation yielded a record-high concentration （322.4 μmol/g） of coordinatively unsaturated metal sites （
Fig. 8e）. These defect-induced Lewis acidic metal nodes （Zr
4+/Hf
4+） paired adjacently with M-OH groups （Lewis bases） to form dense， highly cooperative dual-activation centers （
Fig.8f）. Isotope-labeling experiments and DFT calculations confirmed that these massive defect pairs profoundly lowered the activation energy （
Ea = 43.4 kJ/mol） for direct hydrogen transfer， enabling HE-UiO-66 to achieve an 80.6% yield of furfuryl alcohol （FOL） at 120 ℃ and vastly outperforming its monometallic analogues.
Although pristine HE-MOFs successfully maximize active-site density via structural defects， their isolated metal nodes inherently lack the direct metal-metal interactions required for deep electronic modulation. To transcend this boundary， Liu et al.
[103] utilized a pentametallic MOF as a precursor to synthesize carbon-supported PtCoNiCuZn high-entropy alloy nanoparticles. Breaking the convention of pursuing perfect solid solutions， this work deliberately harnessed thermodynamically driven elemental segregation to tailor the catalytic interface. This segregation induced specific directional charge transfer， highly enriching electron-deficient Pt
δ+ and Co
2+ on the alloy surface （
Fig. 8g）. Such a unique phase-segregated configuration established an optimal bifunctional synergy： the surface high-valence species acted as robust Lewis acids to polarize the carbonyl group， while adjacent multimetallic domains accelerated isopropanol dehydrogenation. Consequently， the catalyst achieved a 94% conversion and 100% FOL selectivity at merely 100 ℃ under ambient pressure.
5.3 Volatile organic compounds elimination
Catalytic oxidation is a highly efficient technology for eliminating various volatile organic compounds （VOCs）. However， balancing low-temperature activity with high-temperature thermal stability remains a critical challenge for conventional metal oxides. Utilizing HE-MOFs as sacrificial precursors to construct high-entropy oxides （HEOs） offers a feasible solution to circumvent this trade-off. This derivation strategy effectively inherits the atomic-level metal dispersion and porous architecture of the parent MOF， while the high-entropy effect confers enhanced thermal durability and intrinsically generates abundant surface defects. Oxygen vacancies play a pivotal role in VOC activation by facilitating oxygen adsorption and reactive oxygen species generation. Nevertheless， recent studies have revealed that oxygen vacancies may also induce a trade-off effect in photothermal catalytic mineralization of multicomponent VOCs， where excessive defect density can accelerate non-radiative recombination or promote undesirable side reactions. Therefore， precisely regulating vacancy concentration in HE-MOF-derived HEOs is essential to maximize catalytic efficiency while maintaining structural robustness
[104].
Recently， Hussain et al.
[105] synthesized a Ce-based HEO （incorporating Mn， Ce， Co， Ni， and Cu） via the controlled calcination of an HE-MOF precursor. Benefiting from the structural heredity of the HE-MOF， the optimized Ce-HEO-400 catalyst possessed a large specific surface area （152.96 m
2/g） and a well-developed mesoporous network. Characterizations， including XPS and H
2-TPR， revealed that the high-entropy microenvironment induced lattice distortion， generating a high concentration of surface oxygen vacancies （O
v） and an elevated Ce
3+/Ce
4+ redox ratio （
Fig.9a~c）. This entropy-driven abundance of O
v and synergistic multimetallic electron transfer significantly accelerated the Mars-van Krevelen （MvK） redox cycle by facilitating lattice oxygen mobility and gas-phase oxygen activation. Consequently， Ce-HEO-400 delivered excellent toluene oxidation kinetics， achieving 50% （
T50） and 90% （
T90） conversion at 180 ℃ and 255 ℃， respectively. Safeguarded by the high-entropy stabilization effect， the catalyst maintained >98.5% conversion over 120 h of continuous operation at 260 ℃. These findings demonstrate that HE-MOF derivation is an effective pathway to construct sintering-resistant， high-performance catalysts for environmental remediation.
5.4 Aerobic oxidation of alcohols
The selective aerobic oxidation of alcohols is a critical transformation for producing high-value fine chemicals. However， developing efficient non-noble metal catalysts is hindered by the inevitable trade-off between active-site density and high-temperature thermal stability. Utilizing HE-MOFs as sacrificial templates to derive defect-rich HEOs offers a feasible solution to preserve hierarchical porosity and lower activation barriers.
Recently， Zhang et al.
[106] synthesized flower-like HEO nanosheets （NiMnCoFeCu） via the controlled calcination of a tailored HE-MOF precursor. Extensive characterizations （e.g.， Raman， EPR， and XPS） revealed a profound structural modulation： the intrinsic lattice distortion within the high-entropy spinel structure triggers the massive formation of surface oxygen vacancies （O
v） （
Fig.9d）. These O
v defects act as electron-rich hotspots to activate molecular O
2 into reactive superoxide radicals （·O
2-）， while adjacent metal nodes coordinate with the alcohol to severely weaken the α-C—H bond （
Fig.9e）. Consequently， driven by this dual-site concerted pathway， the optimized HEO catalyst delivered a 92.3% benzaldehyde yield with >99% selectivity under mild， alkali-free conditions. Rigorously safeguarded by the high-entropy stabilization effect， it retained absolute phase purity over eight consecutive cycles. These findings highlight the critical role of HE-MOF-derivation in engineering kinetically accessible and thermodynamically robust interfaces for selective oxidation catalysis.
5.5 Hydrolysis of ammonia borane
The hydrolytic dehydrogenation of ammonia borane is a compelling strategy for portable hydrogen storage. However， developing efficient non-noble-metal catalysts is hindered by sluggish kinetics and the tendency of multimetallic systems to phase-segregate during synthesis. Utilizing HE-MOFs as precursors to derive carbon-supported HEAs offers a feasible solution to stabilize single-phase solid solutions and optimize electronic structures.
For instance， Chang et al.
[107] synthesized carbon-supported HEA nanoparticles （MnFeCoNiCu） via the controlled pyrolysis of a tailored HE-MOF precursor. Synchrotron-based X-ray absorption near-edge structure （XANES） analysis revealed a profound cocktail effect： electron density transfers from Mn to other constituent elements within the HEA lattice （
Fig.9f）. This charge redistribution fine-tunes the d-band center of the active sites， optimizing the adsorption energetics of the reactants. Consequently， the optimized HEA catalyst exhibited a high turnover frequency （TOF） of 5.76 mol/（min·mol） （based on H
2） and a low activation energy of 32 kJ/mol at 30 ℃， significantly outperforming medium-entropy and phase-segregated analogues. This work emphasized that the superior activity originates primarily from strict elemental uniformity rather than conventional particle size effects， highlighting the critical role of synthetic atmosphere control in translating the compositional complexity of HE-MOFs into robust， highly active alloy catalysts.
HE-MOFs and their derivatives provide a transformative platform for thermal catalysis， elegantly balancing atomic-level precision with macroscopic structural robustness. As intrinsic catalysts under mild conditions， pristine HE-MOFs exploit entropy-driven lattice distortion and targeted defect engineering to construct high-density， cooperative Lewis acid-base pairs， fundamentally lowering kinetic activation barriers. For harsh thermal or redox environments， HE-MOFs serve as ideal sacrificial templates. This derivation strategy leverages spatial confinement and high-entropy stabilization to synthesize defect-rich oxides and alloys. By inheriting the precursor’s hierarchical porosity and atomic dispersion， these derivatives exhibit exceptional resistance to high-temperature sintering and phase segregation.
Looking ahead， HE-MOF-based catalysis must evolve from exploratory synthesis to mechanism-driven rational design. The grand challenge lies in decoupling individual elemental contributions and mapping complex intermetallic synergies within the high-entropy lattice. Bridging this gap requires the deep integration of advanced operando spectroscopies （e.g.， XAS， DRIFTS） with density functional theory （DFT） to capture dynamic active-site evolution. Ultimately， translating “entropy” from a purely thermodynamic stabilizing factor into a precise descriptor for kinetic modulation is imperative to unlock the full potential of next-generation high-entropy catalysts.
6 Photocatalytic applications of HE-MOFs and their derivatives
Photocatalysis technology has attracted extensive attention because of its potential to drive chemical reactions directly by solar energy and its great potential in the fields of energy conversion and environmental treatment
[108-110]. To improve the utilization efficiency of solar energy and achieve efficient photochemical energy conversion， researchers have conducted extensive studies on the design and performance optimization of photocatalysts. However， the conventional inorganic semiconductor photocatalysts （e.g.， TiO
2， ZnO， etc.） generally exhibit issues such as a wide bandgap， limited response to visible light， a narrow solar absorption range， and an insufficient number of active sites on the surface， which severely restrict their catalytic efficiency under actual sunlight conditions
[111-113]. Additionally， the rapid recombination of photogenerated carriers in bulk and on the surface further reduces the quantum efficiency， which makes the construction of high-efficiency photocatalytic systems still face many challenges
[114-116].
In this context， HE-MOFs， as a novel class of multi-component functional materials， are demonstrating unique advantages and broad application prospects in the field of photocatalysis. This coexistence of multiple metals and highly disordered structural characteristics provides new degrees of freedom for regulating the material’s band structure， electron distribution， and surface reactivity. Through precise control of HE-MOFs’ metal composition， ligand types， and microstructure， the number of surface unsaturated coordination metal sites can be significantly increased， the light absorption spectrum range can be broadened， and multi-level energy structures can be constructed. These improvements effectively enhance the separation and migration efficiency of photogenerated carriers， ultimately achieving an overall enhancement in photocatalytic performance.
For instance， Qi et al.
[51] reported p-type high-entropy metal-organic framework nanosheets （HE-MOF-NS） exhibiting exceptional water stability. By incorporating multiple metal nodes （Ni
2+， Mn
2+， Co
2+， and Zn
2+） into a single MOF lattice， they constructed a high-entropy photocatalytic system featuring H
4TBAPy ligands as light-harvesting centers and multi-metal oxide （POMO） clusters as catalytic sites （
Fig.10a）. The UV-Vis spectrum analysis showed that the band gap of HE-MOF-NS was 2.37 eV （
Fig. 10b）， which was much lower than that of the typical water-stable MOFs photocatalysts reported previously.
Compared with single-metal MOF-NS counterparts， the HE-MOF-NS exhibited lower charge transfer resistance （
Fig.10c）， diminished photoluminescence intensity （
Fig.10d）， and accelerated electron transport kinetics， confirming that the random distribution of multi-metal nodes facilitates the construction of a more efficient charge transfer network. Compared with single-metal MOFs， the coexistence of multiple metals with different electronegativities and ionic radii in HE-MOFs induces pronounced lattice distortion and electronic asymmetry. This can lead to the formation of intermediate energy levels within the bandgap， narrowing the effective bandgap and extending light absorption into the visible region. Simultaneously， the random potential fluctuations arising from compositional disorder act as spatial barriers that hinder the migration of photogenerated electrons back to holes， thereby suppressing radiative recombination. As a result， HE-MOFs exhibit prolonged photoluminescence decay lifetimes and reduced charge resistance relative to their single-metal counterparts， directly supporting the enhanced photocatalytic hydrogen evolution performance.
Benefiting from these characteristics， the HE-MOF-NS demonstrated hydrogen evolution performance significantly superior to that of all single-metal MOF nanosheets under visible-light irradiation. The H
2 evolution rate reached 13.24 mmol/（h·g） （
Fig.10e） and maintained stable catalytic performance （
Fig.10f）， ranking among the highest reported values for water-stable MOF photocatalysts.
Furthermore， its ultrathin 2D architecture， high specific surface area， and abundant accessible active sites further promoted the separation of photogenerated electron-hole pairs and enhanced reaction kinetics （
Fig.10g）. Under irradiation， photogenerated electrons originating from the H
4TBAPy ligands efficiently migrate to the POMO clusters to drive proton reduction for H
2 generation （
Fig.10h and
10i）， while the photogenerated holes are consumed by sacrificial agents， thereby achieving a stable and efficient photocatalytic cycle. This work elucidates the advantages of multi-metal synergistic modulation of charge behavior and reaction pathways within high-entropy MOFs， providing a pivotal paradigm for the structural design and performance optimization of HE-MOF materials in the field of photocatalytic hydrogen production.
While HE-MOFs have demonstrated remarkable efficacy in reactions such as photocatalytic hydrogen evolution， their exploration in other photocatalytic domains， including organic synthesis and environmental remediation， remains notably limited. From a materials perspective， the advancement of HE-MOFs still encounters several critical challenges. First， the precise compositional regulation of multi-metal nodes and the underlying structure-property relationships remain elusive. Specifically， the distinct contributions of synergistic or competitive interactions among different metals to photogenerated carrier migration， reaction intermediate adsorption， and selectivity modulation require further elucidation. Second， although certain HE-MOFs exhibit commendable hydrolytic stability， their long-term structural integrity and resistance to deactivation within complex environmental systems， characterized by wide pH ranges， high ionic strengths， or real-world water matrices， lack systematic evaluation.
Furthermore， multi-metal systems inevitably introduce additional energy levels and defect states. Consequently， preventing these sites from acting as carrier recombination centers while achieving precise modulation of the band structure remains a formidable hurdle in the design of HE-MOF photocatalysts. Notably， recent studies on fully conjugated framework materials have demonstrated that rational electronic delocalization can markedly accelerate exciton transport and enhance reactive oxygen species generation in photocatalytic systems. For instance， fully conjugated sp
2 carbon-linked covalent organic frameworks （COFs） have been shown to facilitate exciton migration and improve singlet oxygen photosynthesis efficiency for water remediation
[117]. Although these systems differ fundamentally from HE-MOFs， they provide valuable insights into how electronic structure engineering and exciton dynamics regulation may be leveraged to mitigate recombination losses in high-entropy photocatalysts.
In terms of future development， the application of HE-MOFs in photocatalysis should prioritize the construction of HE-MOF-based heterojunctions or composite systems， such as coupling with semiconductors， carbon materials， or metal single-atom sites， to promote more efficient separation and directional migration of photogenerated electron-hole pairs and thereby suppress carrier recombination losses. At the same time， it is highly desirable to integrate in situ/operando characterization techniques with Density Functional Theory （DFT） calculations to elucidate the intrinsic roles of high-entropy metal nodes in modulating light absorption， charge transfer behavior， and reaction pathways， which will provide a solid theoretical basis for the rational design and optimization of advanced HE-MOF photocatalysts.
7 Conclusions
In conclusion， HE-MOFs and their derivatives demonstrate remarkable application potential in various catalytic systems， including electrocatalysis， thermal catalysis， and photocatalysis. This advantage fundamentally stems from the successful integration and expansion of high-entropy design principles within metal-organic framework systems. HE-MOFs combine the structural designability of ordered crystalline MOFs with the entropy-stabilized properties of high-entropy materials. Their periodic porous framework not only endows the material with an ultra-high specific surface area and efficient reactant/product transport channels， but also significantly enhances the exposure of metal active centers. Compared to single-metal MOFs and traditional multi-metal MOFs with limited metal components （≤3 types）， HE-MOFs exhibit highly disordered random occupation of skeletal sites by multiple metal nodes. The electronic structure differences between different metals can induce continuous and tunable electronic state distributions， thereby effectively optimizing electronic transport pathways and regulating the adsorption behavior of reaction intermediates.
Furthermore， like typical high-entropy systems such as HEAs and HEOs， HE-MOFs exhibit four core characteristics： high-entropy effect， lattice distortion effect， delayed diffusion effect， and “cocktail effect”. These synergistic effects at the thermodynamic and kinetic levels effectively suppress phase separation of metal species， reduce structural evolution rates， and significantly enhance the structural stability and long-term durability of materials under harsh catalytic conditions. Meanwhile， as ideal entropy-stabilized precursors， HE-MOFs can be transformed into various functional materials， including high-entropy alloys， oxides， sulfides， and phosphides， through heat treatment or chemical conversion. These materials largely retain their original characteristics of uniform metal dispersion and hierarchical porous structures. Compared to single-metal or low-entropy counterparts， such derivatives typically exhibit superior electrical conductivity， structural stability， and catalytic activity.
The unique coupling of high entropic stability， tunable electronic structures， and structural diversity has enabled HE-MOFs and their derivatives to evolve into a highly versatile advanced catalytic platform. This development provides a novel research paradigm for rational design and performance optimization of catalysts in energy conversion and environmental remediation. However， as an emerging material system， HE-MOFs still face several critical scientific challenges and technological hurdles that require urgent resolution.
First， from a fundamental theoretical perspective， HE-MOFs represent a significant achievement in the evolution of high-entropy material systems toward organic-inorganic hybrid structures， though their structural essence and entropy stabilization mechanisms require systematic elucidation. Unlike the “primary element” system in high-entropy alloys composed solely of metallic elements， HE-MOFs incorporate non-metallic elements such as C， N， and O from organic ligands in addition to metallic nodes. Whether these elements should be classified as primary elements or included in the framework for calculating configurational entropy， and their actual contributions to entropy stability， remain matters of ongoing debate. Furthermore， given the presence of organic ligands， the spatial spacing between different metal nodes is significantly larger than that in inorganic high-entropy materials such as HEAs. Whether the lattice distortion effect remains dominant or operates in different forms under these conditions still requires further investigation through experimental characterization and theoretical calculations.
Secondly， from an application perspective， existing research primarily focuses on energy-related catalytic reactions such as OER and NRR， while exploration in other catalytic fields remains relatively limited. Unlike HEAs， which generally exhibit metallic conductivity， HE-MOFs typically demonstrate semiconductor behavior， coupled with highly tunable pore structures and excellent chemical stability. Consequently， they hold broad application prospects in environmental remediation fields （e.g.， pollutant adsorption， photocatalytic/thermal degradation）， which could further expand the research boundaries and application scenarios of HE-MOFs.
However， the transition from laboratory-scale ideal aqueous systems to practical wastewater treatment remains a significant hurdle. In real-world complex water matrices， the presence of competitive inorganic ions （e.g.， Cl-， SO42-， HCO3-）， natural organic matter such as humic acids， and extreme pH fluctuations can severely compromise the structural integrity and long-term durability of the coordination frameworks. Humic acids， for instance， can strongly adsorb onto the HE-MOF surface， blocking the hierarchical pore channels and competing for exposed multimetallic active sites. To bridge this gap， future studies must systematically evaluate HE-MOFs under realistic operational conditions. Promising strategies to overcome their intrinsic vulnerability in harsh environments include targeted surface functionalization to enhance hydrophobicity， constructing core-shell architectures to shield active sites， and utilizing defect engineering to strengthen metal-ligand coordination bonds.
Interestingly， considering that they have shown active responses in thermo-， photo-， and electrocatalytic processes， advances in terms of chemical and thermal stability of these structures could open new routes for the exploration of multi-energy systems where， e.g.， thermo-photocatalytic or electro-photocatalytic schemes are used to find synergistic effects in applications
[118-121].
Thirdly， from an engineering perspective， the large-scale preparation of materials is a critical prerequisite for practical applications. Among the reported synthesis strategies for HE-MOFs， the solution-phase method is considered the most promising for industrial scaling， though it still generally requires high temperatures， high pressures， or prolonged reaction conditions. Future research could further explore novel pathways for controllable synthesis of HE-MOFs under ambient conditions to reduce energy consumption and enhance process feasibility.
Finally， the highly flexible combination of metal components with organic ligands in HE-MOFs systems， while offering unprecedented structural and performance tuning capabilities， also significantly increases experimental screening costs. With the rapid advancement of machine learning and data-driven materials science， integrating computational predictions with high-throughput experiments is expected to substantially accelerate the composition design， structural optimization， and performance evaluation of HE-MOFs. Based on this， establishing a material database for HE-MOFs and introducing machine learning-assisted design will become one of the key development directions in this field in the future.
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