1 Introduction
Electrocatalysis is recognized as a highly sustainable and renewable approach to addressing environmental concerns and energy shortages
[1]. Compared to combustion-based processes, electrochemical processes have a higher theoretical thermodynamic efficiency and produce fewer pollutants
[2⇓-4]. In fact, many electrocatalytic reactions result in the generation of water or economically valuable products. For example, water electrolysis enables green hydrogen production, while CO
2 reduction and N
2 electrochemical fixation facilitate the creation of high-value products
[4,5]. Additionally, electrochemical oxidation processes are promising in wastewater treatment and pollutant removal, such as urea electrooxidation and enrichment of heavy metal ions
[3,6,7]. Given the high efficiency of these electrocatalytic processes, there is a significant demand for rationally designed and highly active electrocatalysts.
Metal-organic frameworks (MOFs) are basically composed of metal nodes and organic ligand units (linkage)
[8]. Owing to their active metal sites, large specific surface areas, and structural well-designed, these traditional MOFs, as heterogeneous catalysts for various catalytic reactions, have gained significant attention
[9⇓~11]. However, when it comes to electrocatalysis, most existing MOF-based approaches rely on frameworks with low conductivities, resulting in low current densities (< 5.0 mA·cm
-2)
[12⇓~14]. To overcome these limitations, several approaches were proposed, such as mixing with electroactive materials, conjugating with a similar structure to form conductive hybrids, etc. Among them, conductive MOFs (c-MOFs) have emerged as a promising solution due to their intrinsic structural conductivity and excellent electron transfer capabilities
[12,15⇓~17]. Different from the traditional MOFs, the organic ligand units in c-MOFs are generally conjugated organic ligands (
e.g., 1,2,5,6,9,10-triphenylene hexathiol (THT), 2,3,6,7,10,11-hexaiminotriphenylene (HITP), and hexaazatriphenylene (HATN)) connected through M-N
4 linkages (
Fig. 1a), creating a fully π-conjugated framework within the matrix with good conductivity. This excellent conductivity offers new possibilities for utilizing c-MOFs in electrocatalysis
[9,10,18].
In recent years, several studies have highlighted advancements in the use of c-MOFs as electrocatalysts in this field. Jiang
et al.
[20] offered a comprehensive review of the latest progress in electrocatalysis and electrochemical sensors using c-MOFs. Feng
et al. demonstrated the potential of 2D c-MOFs in multifunctional devices, including field-effect transistors (FETs), superconductors, chemiresistors, and photodetectors
[1,21]. Hu
et al.
[22] comprehensively reported on the use of c-MOFs in heterogeneous electrocatalysis, covering synthetic approaches and main electrochemical applications. Despite the exploration of various c-MOFs, phthalocyanine-based c-MOFs have been relatively overlooked. Our group developed NiPc-based c-MOFs employing 2,3,9,10,16,17,23,24-octaamino-phthalocyaninato nickel(Ⅱ) for nitrite determination and flexible supercapacitors based on its specific surface area and excellent electrical conductivity
[9,10]. c-MOFs based on phthalocyanine complexes (referred to as phthalocyanine-based c-MOFs) are a new class of layer-stacked c-MOFs with conjugated coordination structures that bring exceptional properties, including specific active species, tunable crystal structures, stability, remarkable electrical conductivity, and tailorable band gaps, presented promising activity in electrochemical scenarios (
Fig. 1)
[18].
Various synthesis methods have been established for phthalocyanine-based c-MOFs, which can be broadly classified into (i) top-down and (ii) bottom-up approaches, including exfoliation
[23], interfacial synthesis, layer-by-layer deposition
[24], solvothermal treatment [
10], and surfactant-assisted synthesis
[18,25,26]. The synthetic approaches for phthalocyanine- based c-MOFs have been previously demonstrated and summarized. Thus, this work did’t focus on that aspect
[27]. Their high electrical conductivity allows for efficient electron transfer, leading to improved catalytic activity in these reactions. Thereby, we firstly proposed several conductive mechanisms of phthalocyanine-based c-MOFs, then summarized the recent advances in phthalocyanine-based c-MOFs towards electrocatalytic applications, such as the water electrolysis (hydrogen evolution reaction and oxygen evolution reaction), oxygen reduction reaction, CO
2 reduction reaction, and nitrogen reduction reaction. Finally, the current challenges and perspectives for the further development of phthalocyanine-based c-MOFs in the field of electrocatalysis are also highlighted.
2 Conductive mechanisms
Phthalocyanine-based c-MOFs are a type of two-dimensional layered MOFs that possess good conductivity due to their conjugated organic ligands. For example, Cao
et al.
[28] developed this kind of c-MOFs by integrating NiPc-based building blocks into porous NiPc-NiN
4 c-MOFs. The planar NiPc motifs were connected by NiN
4 nodes, resulting in a highly conductive material with an electrical conductivity of 2.39×10
-4 S·m
-1. This excellent conductivity is accredited to the d-π conjugation orbitals between the NiN
4 nodes and NiPc-substituted o-phenylenediamine, which further tends to be a strong electron delocalization system between the layered c-MOFs. Dincă
et al.
[12] summarized electrical c-MOFs based on a large amount of experimental studies. The conductivity is vitally important for phthalocyanine-based c-MOFs in electrocatalysis, so we introduced the main principles related to the conductive mechanism of c-MOFs based on previous report of Dincă
et al., which is also suitable for phthalocyanine-based c-MOFs.
Generally, the efficacy of charge transfer in MOFs can be quantified by their conductivity, which depends on two important factors: (i) carrier mobility and (ii) carrier concentration
[12]. Two general conductive mechanisms for charge transport are band-like transport, which involves strong interactions and the formation of continuous energy bands, and hopping transport, where charge carriers are discretely localized with high barriers between networks (
Fig. 2). To highly achieve conductivity in MOFs, five broad approaches have been proposed, as follow: (i) a large number of consecutive coordination bonds within the matrix could initiate an electron delocalization domain, increasing high charge mobilities and decreasing band gaps; (ii) inorganic metal nodes and organic ligands of MOFs can resemble two-dimensional metal-organic analogs like graphene, allowing for charge transport through extended conjugated frameworks; (iii) charge transfer through space pathway between π-π interactions of organic linkers, just as we mentioned the case of porous NiPc-NiN
4 c-MOFs that Cao
et al.
[28] builted with NiPc-based building blocks.
Charge transport can generally be attributed to either hopping transport or band-like transport mechanisms. However, distinguishing between these two mechanisms in the context of charge transport in crystalline MOFs would be challenging, especially in samples with a high amount of grain boundaries and structural defects. This makes it difficult to determine the specific electron/charge transfer mechanism. As a result, the potential for the hopping conduction mechanism may be limited, especially at lower temperatures. On the other hand, in frameworks where crystallographic pathways for band-like transport are not identifiable, it is reasonable to assume that conductivity occurs through a hopping mechanism (
Fig. 3a). In the case of phthalocyanine-based c-MOFs, the presence of redox-active metal species or organic linkers, combined with close spatial proximity between these components, could potentially enhance charge hopping. In addition, MOFs with porous structures can be utilized to introduce functional guests via post-synthetic strategies, thereby promoting conductivity (
Fig. 3b). Such as, Zeng
et al.
[29] constructed Zr(IV)-based MOF consisting of zirconium salt and 1,5-bis(methylthio)naphthalene- 2,6-dicarboxylic acid (TNDC). Then, the conductivity of the post-synthetic processed Zr-TNDC presents an excellent conductivity of 3.16 × 10
-2 S·m
-1, which is more than 50 times compared to the bulk Zr-TNDC (7.88 × 10
-5 S·m
-1) under the same test conditions. These approaches offer strategies to improve the conductivity of MOFs and expand their possible functions in various electrochemical scenarios.
3 Electrocatalysis
Electrocatalysis is a highly promising strategy to produce clean energy, highly-added industrial chemicals and environmental conservation
[30]. This approach offers several advantages, including mild and soft reaction conditions, controllable selectivity, and scalability
[6,30].
This technology makes it possible to efficiently reduce the emission of environmental pollutants, combined with renewable energy
[31]. In this context, phthalocyanine-based c-MOFs hold great potential in electrocatalysis due to their unique molecular-level modification capabilities. Characterized by their adjustable pore sizes, extensive surface areas, and varied metal and ligand configurations, phthalocyanine-based c-MOFs offer a versatile platform for developing novel electrocatalysts. This leads to improved charge transfer, increased active site accessibility, and optimized reaction kinetics.
3.1 Water electrolysis
Electrochemical water splitting is a pivotal approach for green hydrogen production with sustainable energy, which contains an anodic reaction (oxygen evolution reaction, OER) and a cathodic reaction (hydrogen evolution reaction, HER) in the whole electrolyztic process. Until now, the high-performance electrocatalysts for HER and OER have mainly been inorganic materials, especially for precious metal alloys
[5,32,33]. In this section, HER and OER are introduced with typical examples, equipped with their mechanisms.
HER process involves 2-electron transfer, which is easier than the 4-electron transfer of the OER process. In the first step, hydrogen adsorption occurs on the electrode surface to form H
* (
* is the active site). In an alkaline solution, the reaction mechanism follows the following steps: H
2O + e
− → H
* + OH
− (Volmer step); H
2O + e
− + H
* → H
2 + OH
− (Heyrovsky step). Excellent HER electrocatalysts require moderate hydrogen binding energy. Metalophthalocyanines (MPcs), such as Ni, Fe, and Co, have been extensively studied for their potential in electrochemical hydrogen production when combined with composites like glass carbon electrodes and carbon nanotubes
[13,14]. However, there has been limited research on the use of phthalocyanine-based c-MOFs for investigating HER
[4]. For example, these phthalocyanine-based c-MOFs (MPc-pz), which incorporate MPc molecules and pyrene units connected by pyrazine (pz) linkages, was synthesized with different metal sources within MPc (M= Fe, Co, Ni, Mn, Zn, and Cu). The as-prepared samples were intended to investigate the electrochemical nitrogen reduction reaction (NRR), and presented improved activity and selectivity towards electrocatalytic NRR
[34]. Interestingly, FePc-pz exhibited outstanding catalytic activity with a high NH
3 yield rate compared to the various synthesized MPc-pz (
Fig. 4a). Owing to the competing reaction between NRR and HER in the cathodic area, the higher NRR activity means the lower HER. In fact, the energy barrier for forming
*H on CoPc-pz was found to be smaller than that for FePc-pz, indicating faster HER kinetics (
Fig. 4b). However, due to the limited reports on phthalocyanine-based c-MOFs in the HER process, it is difficult to seek enough cases to demonstrate the HER activity of phthalocyanine-based c-MOFs positively. Several alternative reactions, such as NRR, OER, and other small molecule oxidation reactions, are regarded as competing reactions. Thereby, the activity of the opposite reaction can also be used to evaluate the HER activity to some extent. In addition, density functional theory (DFT) calculations could offer valuable insights into the electrocatalytic pathways of these macromolecular complexes in this example.
The OER process is an important half-process in water splitting electrolyzers, but its sluggish kinetics require a high overpotential to promote OER activity. Although benchmark electrocatalysts like IrO
2 and RuO
2 have been extensively studied, phthalocyanine- based c-MOFs could serve as efficient and abundant alternative electrocatalysts to reduce costs and improve performance. Jia
et al.
[18] developed a NiPc-based c-MOF through a bottom-up approach. Then, the prepared c-MOFs were deposited on FTO (fluorine- doped tin oxide) for electrocatalytic OER, which demonstrates excellent activity with a low overpotential and onset potential. This study firstly reported such performance in a NiPc-based c-MOF.
In a separate study, Song
et al.
[35] explored a method to modulate the electronic configurations of phthalocyanine-based c-MOFs by introducing dual metal clusters (
Fig. 5a). High-resolution TEM (HRTEM) image presentes a square lattice with a spacing corresponding to the (100) crystallographic planes of the NiPc-Ni c-MOF (
Fig. 5b). The dual-metal c-MOFs with optimized structure showe a low onset overpotential and Tafel slope. The authors also explored the different modulations between Ni and Zn clusters within the matrix and their electrocatalytic OER activity (
Fig. 5c). Such a relationship study could also be designed and explored for other electrocatalysis. The densities of states (DOS) and PDOS (projected-DOS) could help us understand the electronic structure of the material or individual orbitals through DFT calculations (
Fig. 5d). PDOS patterns of dual-metal c-MOFs demonstrate that the electronic structure interaction between Ni-O
4 and Ni-N
4 clusters is better than other configurations, which could enhance their OER activity (
Fig. 5e). Unlike the HER study of phthalocyanine-based c-MOFs, OER and their alternative reactions were investigated directly on the phthalocyanine-based c-MOFs. More work was focused on the rational design of MPc complexes and linkages and microenvironmental modulations, to optimize their electronic structure and improve their conductivity, meanwhile exposing more active sites for efficient electrocatalytic reactions.
3.2 Oxygen reduction reaction
The oxygen reduction reaction (ORR) plays a critical role in high-efficiency proton exchange membrane fuel cells (PEMFCs), metal-air batteries (such as Li-air, Zn-air, and Mg-air), and other electrochemical energy conversion devices
[36]. The ORR mechanism is complex, which involves various steps such as adsorption, dissociation, recombination, and desorption of oxygenated intermediates. It also involves interfacial transfer of 4-electron and 2-electron processes
[37]. Overcoming the sluggish kinetics of the ORR requires the discovery of high-quality catalysts.
Zhong
et al.
[38] demonstrated a CuPc-based conjugated c-MOF with square-planar cobalt bis(dihydroxy) complexes (Co-O
4) as linkages (PcCu-O
8-Co), which was synthesized through the solvothermal method, resulting in layer-stacked structures (
Fig. 6a). The half-wave potential (
E1/2) of PcCu-O
8-Co c-MOF was found to be 0.83 V vs RHE, which is comparable to that of commercial Pt/C (
Fig. 6b). When PcCu-O
8-Co c-MOF was combined with CNTs, it exhibites excellent ORR activity in alkaline media. This is due to the extensive coverage of electrochemically Co active sites and porous structure. Based on the in situ Raman spectroscopy, an advanced technique for in situ characterization, they allow the detection of reaction intermediates attached to catalyst surfaces, which provides a basis for proposing reaction pathways leading to specific products through theoretical calculations
[39]. Herein, in situ Raman spectra with various applied potentials and theoretical modeling confirmed that the cobalt nodes in the c-MOF were active sites for the ORR (
Fig. 6c). Based on the obtained results, a proposed ORR mechanism was presented (
Fig. 6d).
3.3 CO2 reduction reaction
Extensive research has been conducted on the electrochemical reduction of CO
2 (CO
2RR) due to its potential for sustainable CO
2 conversion, carbon recycling, and renewable energy storage, making it a highly valuable process
[40,41]. As for electrochemical thermodynamics, proton-coupled pathways such as 4-electron, 6-electron, and 8-electron processes are preferred
[42,43]. Cu is widely recognized as the primary metal capable of efficiently converting CO
2 into significant quantities of value-added products through electrochemical reduction
[44]. The diverse products of CO
2RR through electrochemical reduction contribute to the complexity of their reaction mechanisms. However, regular MOFs exhibit poor electrical conductivity due to the inherent structure, and they need other conducting substrates (such as Nafion membrane, nickel foam, and carbon-based materials) to improve the current density in CO
2RR. Metallophthalocyanine complexes (MPcs) have displayed potential in catalyzing CO
2 reduction. However, individual metal complex-based molecular electrocatalysts demonstrate lower efficiency and specificity in comparison with Au, Ag, and Cu-based materials. A successful approach for achieving high current density in CO
2RR involves integrating a substantial amount of electroactive metal complex-based catalysts into porous conductive materials. Porous coordination polymers based on MPc with periodically arranged metal ions/clusters and organic ligands are considered as promising candidates for CO
2RR due to their extensive surface areas, significant CO
2 adsorption capabilities, and a high concentration of adjustable active sites.
Huang and co-workers
et al.
[45] developed a conductive NiPc-based complex using 2,3,9,10,16, 17,23,24-
octa-aminophthalocyaninato Ni(Ⅱ) and
tert-butylpyrene-tetraone for efficient CO
2RR. The prepared complex exhibited high selectivity towards CO production with a large current density due to its high conductivity and more accessible active sites. In the same group, they synthesized NiPc-NiO
4 MOF nanosheets, which differ from the above structure and exhibit a high selectivity (nearly 100%) of CO production with high current density (
Fig. 7a)
[46]. The obtained NiPc-NiO
4 c-MOF exhibits strong conductivity due to the in-plane full p-d conjugation between the NiPc and NiO
4 linkages. The outstanding electrocatalytic CO
2RR activity of the prepared nanosheets can be attributed to their high electrical conductivity, available single active sites, and significant CO
2 adsorption capacity (
Fig. 7b). Moreover, DFT calculations showed that the nickel center in NiPc acts as the active site. NiPc-NiO
4 c-MOF demonstrates superior activity compared to MPc molecules, which was attributed to its rapid electron transfer capability and exceptional reducibility (
Fig. 7c). It can be concluded that phthalocyanine-based c-MOFs presents exceptional conductivity owing to the structural merit, including the conjugated molecular rings and in-plane full p-d conjugation between MPc and linkages. In addition, to obtain carbon-based products with high selectivity and efficient production after the CO
2RR process, it is necessary to rational design the MPc and linkages. For attention, the regulation mechanism of the structure-activity of phthalocyanine-based c-MOFs towards electrocatalytic CO
2RR still needs further exploration.
3.4 N2 reduction reaction
Electrocatalytic NRR is a sustainable approach for nitrogen-to-ammonia generation in gas-phase electrocatalysis, but it still suffers from the low ammonia production issue due to the competing H
2 evolution reaction
[47]. Moreover, the inert nature of triple bonds of N
2 makes it difficult to achieve nitrogen conversion under normal conditions. In response to this challenge, the electrochemical NRR combined with renewable energy has emerged as a viable and sustainable alternative to the high temperature/pressure Harber-Bosch process for ammonia production. This approach offers a promising solution to the challenges associated with nitrogen conversion
[48].
The well-organized MOFs with microporous structures played a vital role in the NRR application. In this context, 2D c-MOFs based on phthalocyanine could serve as promising NRR electrocatalysts due to (i) the layer-stacked structure with a high surface area, which can offer a substantial number of easily accessible active sites and adequate mass transport, and (ii) the inherent electrical conductivity, which can be advantageous for efficient electron transfer behaviors. Phthalocyanine-based c-MOFs with a microporous structure have been proven to be essential in gas-phase catalysis. Feng
et al.
[34] reported the initial instance of crystalline 2D phthalocyanine-based c-MOFs integrated with abundant M-N
4-C sites as efficient catalysts, realizing both improved activity and selectivity in nitrogen-to-ammonia conversion. This example was previously mentioned in Section 3.1 as HER application.
Based on their studies, the researchers used MPc and pyrene units to prepare MPc-pz through a solvothermal approach (
Fig. 8a, b). Among these catalysts, FePc-pz with Fe-N
4 sites exhibited the highest ammonia yield rate (33.6 μg·h
-1·mg
cat-1) and Faradaic efficiency (FE, 31.9%) at −0.1 V (
versus reversible hydrogen electrode (vs RHE) compared to those with other MPc-pz with M-N
4 sites), making them one of the most effective NRR electrocatalysts. DFT calculations further confirm the effectiveness of FePc-pz, which contains Fe-N
4 active sites for electrocatalytic NRR (
Fig. 8c~e). Due to the columnar stacking of porous structure, high in-plane π-conjugation for fast electron transfer, and abundant Fe-N
4 active sites, FePc-pz exhibits exceptional catalytic NRR activity and an impressive ammonia yield rate. The significant properties of the FeN
4 active sites, including optimal substrate adsorption energy and low energy barrier for the rate-determining step, enable efficient N
2 activation and conversion.
3.5 Other possible reactions
The electrochemical explorations of phthalocyanine-based c-MOFs are not limited to the above-mentioned water electrolysis (HER and OER), CO2RR, NRR and ORR. For example, the urea oxidation reaction (UOR), hydrazine oxidation reaction (HzOR), and biomass oxidation reaction (BmOR) can also contribute to energy-saving hydrogen production and environmental protection in specific situations. Phthalocyanine-based c-MOFs can also be used to understand the common mechanisms of reported redox reactions and to regulate their coordination structure and micro-environmental electronic states for potential electrochemical reactions. Phthalocyanine- based c-MOFs can also refer to the common mechanisms of reported redox reactions and regulate their coordination structure and micro-environmental electronic states for the potential electrochemical reactions. It is important to note that different electrochemical reactions occur under specific reaction conditions, such as UOR preferring alkaline electrolytes and HER being easier in acidic solutions. These conditions should be considered in the development of novel phthalocyanine-based c-MOFs.
4 Challenges and outlook
Various phthalocyanine-based c-MOFs in electrocatalysis, specifically in water electrolysis and CO
2RR investigations, have been extensively studied. These c-MOFs have been demonstrated enhanced activity in various electrochemical scenarios, which thanks to their inherent advantages. However, there is still a significant challenge in developing highly active phthalocyanine-based c-MOFs, despite the strong desire for their advancement (
Fig. 9).
4.1 Catalytic activity
Electrocatalytic reactions encounter various issues, such as high overpotential, low current density, unsatisfactory selectivity, and susceptibility to poisoning. To tackle these challenges, understanding the reaction mechanism and assessing the impact of different factors on kinetics is crucial for the design and synthesis of high-performance phthalocyanine- based c-MOF catalysts. Advanced techniques like DFT calculations and in situ characterizations can provide insights into the electrocatalytic reactions, surface state changes, and atomic structure transformations. By utilizing those techniques, metal nodes or organic ligands can be tuned to decrease the free energy of adsorption and desorption, enhancing the activity of phthalocyanine-based c-MOF catalysts. Additionally, optimizing the morphologies and sizes of the catalysts can increase the number of exposed active sites, further amplifying their catalytic activity. By systematically addressing these considerations, it becomes feasible to overcome the existing challenges and develop highly efficient phthalocyanine-based c-MOF catalysts for electrocatalytic reactions.
4.2 Conductivity
The limited conductivity of pristine MOFs, attributed to the inherent properties of organic ligands, poses a significant constraint on the development of highly electroactive MOFs. Enhancing the conductivity of phthalocyanine-based c-MOFs can be achieved through various strategies, including morphology control, component manipulation, and structural engineering. For instance, the use of high-quality and highly crystalline phthalocyanine- based c-MOFs, such as single crystals, ensures efficient charge transfer and prevents conductivity loss. Additionally, incorporating heterostructures in phthalocyanine-based c-MOFs opens possibilities for designing highly efficient electrocatalysts. An effective approach involves anchoring MOF films onto conductive substrates, which further enhances conductivity and catalytic performance. These advancements in charge transport pathways and the increase of mobile charge carriers contribute to improved conductivity in phthalocyanine-based c-MOFs, enabling their potential as highly electroactive materials.
4.3 Selectivity
An effective electrocatalyst not only demonstrates outstanding catalytic activity but also exhibits exceptional selectivity. Selectivity plays a crucial role in electrocatalytic reactions, encompassing various processes such as ORR (2-electron and 4-electron pathways), CO2RR (C1 and C2 + products), and NRR (ammonia and other nitrogen oxides). For example, the oxygen reduction reaction is a key process in proton exchange membrane fuel cells. The 4-electron pathway on the electrocatalyst is highly desirable for improving the fuel cell’s current density and powder density. However, oxygen reduction may follow the 2-electron pathway to generate hydrogen peroxide, and the hydroxyl radical can be detrimental to the membrane's longevity and the stability of the electrocatalyst. Therefore, precise control of the structure of phthalocyanine-based c-MOFs with sufficient active sites can effectively facilitate ORR with the 4-electron pathway. Additionally, the inter-distance, often overlooked, plays a critical role in controlling the diffusion and adsorption of intermediates, thereby contributing to improved selectivity. By comprehensively addressing these factors, advancements in electrocatalysis can be achieved, taking into account both catalytic activity and selectivity.
4.4 Stability
Stability, as a crucial practical indicator for long-term operation, can be understood through variations in morphological structure, composition, and size information. Just like catalytic activity, selectivity and stability can be enhanced by adjusting metal centers of MPc or linkages (organic ligands and metal nodes) within the matrix. Additionally, utilizing metal centers with high oxidation states can contribute to enhanced stability. The capacity to modify metal nodes and organic ligands allows for the design and acquisition of materials with specific structures and corresponding applications. By considering stability alongside other factors, it is feasible to develop materials that demonstrate excellent catalytic activity as well as sustain performance over extended periods of operation.
5 Conclusion
In this work, the recent advancements in phthalocyanine-based c-MOFs for a various electrocatalytic reactions were summarized, encompassing water electrolysis (HER and OER), ORR, CO2RR, and NRR. These c-MOFs exhibit unique physicochemical properties, including a large surface area, high porosity, and adjustable porous structure, exceptional crystallinity, and superior conductivity. Moreover, they possess an abundance of catalytic active sites with ultrahigh density, combining the advantages of heterogeneous electrocatalysts. Consequently, phthalocyanine-based c-MOFs have been thoroughly explored for diverse electrocatalytic applications. Various strategies have been developed to fabricate these materials, focusing on enhancing charge transport pathways and increasing the number of mobile charge carriers. To further improve their catalytic performance (activity and selectivity) and stability, it is crucial to utilize advanced in situ characterization techniques and theoretical calculations that can elucidate the catalytic mechanisms of active sites. This work could guide the development of phthalocyanine-based c-MOF electrocatalysts with superior activity and make them highly attractive for electrocatalysis applications, contributing to a more sustainable and environmentally friendly future.
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