Since the widespread acceptance between the 1960s and 1970s， condensed matter physics has undergone rapid development. Condensed matter physics primarily investigates the geometric and electronic structures of solid and liquid substances， as well as the resulting microscopic and macroscopic physical phenomena such as sound， light， electricity， magnetism， heat， etc. Meanwhile， the field of chemistry has also evolved significantly， especially in the last two decades， with advancements in theoretical chemistry and chemical characterization techniques. Researchers have gradually come to realize that chemical reactions are not merely straightforward transformations from reactants to products. The structural hierarchy of the reaction system plays a crucial role in the progression of chemical reactions. There has been a growing emphasis on the in-situ characterization of chemical reactions， and efforts have been made to explore the dynamic changes in the material structures at different levels within the system under reaction conditions. These developments can be considered as the nascent stages of condensed matter chemistry research. Physics and chemistry have always been intertwined and mutually reinforcing natural sciences. Currently， new phenomena and theories in condensed matter physics continue to emerge. Introducing these new physical phenomena and theories into chemical research is a highly worthwhile exploration area. The present review will briefly introduce some relatively recent concepts in condensed matter physics （e.g.， surface plasmon polariton， topological insulators， quasicrystals， local micro-electric/magnetic fields， light-matter interactions， alternating magnets， etc.） and their applications in chemistry. The aim is to illustrate the application potentials of cutting-edge condensed matter physics research in chemistry， provide insights into advancing traditional chemical research to the realm of condensed matter chemistry， and contribute to the development of condensed matter chemistry.
Contents
1 Introduction: from solid-state physics to condensed matter physics
2 Condensed matter in chemical reaction systems
2.1 Dynamic interface configurations in reactions
2.1.1 Reactions on solid-gas interfaces
2.1.2 Reactions on solid-liquid interfaces
2.1.3 Reactions on solid-solid interfaces
2.2 External electric field
2.3 Other external fields
2.4 Microenvironments
3 New chemical methods from the new concepts of condensed matter physics
1 Introduction: From Solid-State Physics to Condensed Matter Physics
Condensed matter physics is an important branch of modern physics, whose theoretical framework integrates fundamental concepts from statistical mechanics, quantum field theory, and electromagnetism. The research scope encompasses: (1) material synthesis and structural characterization; (2) physical property measurements and data analysis; and (3) theoretical modeling and elucidation of underlying physical mechanisms. In terms of organizational structure, the Chinese Physical Society does not have a dedicated Condensed Matter Physics Division; instead, it employs 31 specialized committees to achieve a more refined disciplinary classification, among which 22 (accounting for over 70%) are closely related to condensed matter physics. According to incomplete statistics, at least 63 international academic conferences and seminars focused on condensed matter physics were held worldwide in 2024, reflecting the high level of attention and broad interest that this field has garnered within both domestic and international physics communities.
Condensed matter physics primarily investigates the physical properties of many-particle systems in which particles interact with one another. In a broad sense, except for ideal gases, almost all systems in the real material world exhibit interactions—ranging from weak to strong—among their constituent particles; therefore, they can all be classified under the umbrella of condensed matter research. However, contemporary condensed matter physics mainly focuses on solid and liquid states, that is, systems where particle interactions are relatively strong. By combining experimental and theoretical approaches, condensed matter physicists observe, understand, and predict the physical behaviors of these systems, thereby providing crucial support for the advancement of materials science and related technologies.
The exploration of the condensed states of matter can be traced back to the 19th-century studies on gas–liquid phase transitions conducted by British chemists Humphry Davy and Michael Faraday［1］. Building upon this work, Irish chemist Thomas Andrews introduced the concept of the “critical point” to describe a state in which the gaseous and liquid phases coexist without distinct boundaries; Dutch physicist Johannes van der Waals subsequently provided a robust theoretical framework for this phenomenon［2］. A decisive breakthrough in this field occurred in 1908, when Scottish chemist James Dewar and Dutch experimental physicist Heike Kamerlingh Onnes independently achieved the liquefaction of helium, ushering in a new era of low-temperature physics［3］. The successful liquefaction of helium provided crucial prerequisites for Heike Kamerlingh Onnes’s discovery, three years later in 1911, of superconductivity in mercury at a temperature of 4.16 K, marking a milestone event in the history of condensed matter physics［4-5］. For this achievement, Onnes was awarded the 1913 Nobel Prize in Physics. Subsequently, another fundamental property of superconducting materials—diamagnetism (the Meissner–Ochsenfeld effect)—was jointly discovered in 1933 by German physicists Fritz Walther Meissner and Robert Ochsenfeld［6］.
Human understanding of magnetic phenomena has a long history. As early as the 6th century BC, the ancient Greek philosopher Thales recorded observations on lodestone［7］; in China, discussions on magnetism can also be found in the "Guiguzi" dating back to the 4th century BC and in Wang Chong's "Lunheng" from the Eastern Han dynasty［8-9］. However, systematic scientific research on magnetism as a physical phase transition did not begin until modern times. A major milestone was the work of the French scientist Pierre Curie, who elucidated the phase transition process whereby ferromagnetic materials transform into paramagnetic states at a specific temperature—later known as the "Curie temperature"—and formulated the Curie law［10］. In 1907, building upon Curie's findings, the French physicist Pierre-Ernest Weiss introduced the concept of "magnetic domains" and, using mean-field theory, refined the Curie law to propose the Curie–Weiss law, which provides a more accurate description of the magnetic susceptibility of materials at high temperatures［11-12］. The microscopic description of magnetic phase transitions was pioneered by the Ising model, proposed in 1925 by the German physicists Wilhelm Lenz and Ernst Ising［13］. The exact solution of this model revealed that one-dimensional periodically arranged magnetic dipoles cannot undergo spontaneous antiferromagnetic–ferromagnetic phase transitions, whereas the two-dimensional square-lattice model represents the simplest system capable of exhibiting ferromagnetic–paramagnetic phase transitions［14］. In the same year, the Dutch–American theoretical physicist George Uhlenbeck, in collaboration with Samuel Goudsmit, discovered electron spin. This discovery fundamentally revealed the quantum origin of material magnetism and was directly confirmed by the renowned Stern–Gerlach experiment［15］。
As physics developed in the late 19th century, a series of experimental phenomena that could not be explained by classical theories began to emerge, signaling an impending profound revolution in physics. Through his research on cathode rays, British physicist Sir Joseph John Thomson not only discovered the existence of the electron but also revealed the discrete nature of electric charge. Subsequently, in the very first year of the 20th century, Max Planck, in order to perfectly account for the blackbody radiation spectrum, first proposed the hypothesis of energy quantization: the energy emitted by a harmonic oscillator is an integer multiple of its intrinsic frequency, with the proportionality constant linking the two being the “Planck constant.” This revolutionary idea was further developed by Albert Einstein in 1905. Einstein extended the concept of energy quanta to light, proposing the photon hypothesis (later referred to as the photon), and on this basis successfully explained the photoelectric effect on metal surfaces［16］. These early, fragmented quantum ideas collectively undermined the foundations of classical physics and paved the way for the emergence of new theoretical frameworks.
The leap from "old quantum theory" to a systematic theory began in 1924. French physicist Louis Victor de Broglie, the Duke of Broglie, proposed the "matter-wave hypothesis," extending wave–particle duality from photons to all material particles, which marked a turning point for the new theory［17-18］. In the same year, German theoretical physicist and mathematician Max Born first employed the term "quantum mechanics" in his work［19-20］, formally heralding the birth of an entirely new branch of physics. The establishment of quantum mechanics provided humanity with an unprecedentedly powerful theoretical framework for understanding the microscopic behavior of atoms, molecules, and even macroscopic matter. It not only serves as the common foundation for studying all fundamental interactions except gravity but also, through its profound principles and robust analytical capabilities, has greatly advanced research in materials science, directly giving rise to condensed-matter physics, which aims to understand and control the collective behavior of many-particle systems. Therefore, a review of the developmental trajectory of quantum mechanics is a necessary prerequisite for comprehending the theoretical foundations of condensed-matter physics.
Matter, based on the differences in interactions among its internal particles, can exist in various states, including solid, liquid, gas, plasma［21］, Bose–Einstein condensate［22］, and fermionic condensate［23］. Among these, the solid and liquid states are collectively referred to as condensed phases due to the significant and non-negligible strong interactions between their constituent particles.
In condensed matter, solid materials can be further classified into three categories based on their inherent orderliness: crystals, amorphous solids, and quasicrystals［24］. Crystals, characterized by long-range translational symmetry and a simple, well-defined structure, have long served as the cornerstone of solid-state physics theory. In contrast, amorphous solids exhibit long-range disorder and structural complexity, which pose challenges for theoretical studies; however, their abundant active sites with non-stoichiometric coordination numbers provide unique advantages for catalytic and other chemical applications. Situated between these two extremes are quasicrystals—an exceptional class of solid-state materials that possess only long-range orientational order (e.g., fivefold, sevenfold, eightfold, tenfold, or twelvefold rotational symmetry) but lack translational periodicity［25］. Quasicrystalline materials, predominantly alloys, demonstrate application potential in functional coatings and material reinforcement due to their low thermal and electrical conductivity, high hardness, and other distinctive properties［26］.
Initially, the study of crystallography, metallurgy, mechanics of materials, and optical, electrical, and magnetic properties was relatively independent. It was not until the 1940s that these topics were systematically integrated into "solid-state physics." Thanks to major breakthroughs in fields such as semiconductors, superconductivity, and nuclear magnetic resonance, solid-state physics developed rapidly to meet the technological demands of industry. However, as research deepened, physicists gradually came to realize that non-solid systems—such as liquids and superfluids—share profound commonalities with solids in terms of physical laws. Consequently, the limitations of the term "solid-state physics" became increasingly apparent.
This conceptual evolution ultimately led to the establishment of the more inclusive term "condensed matter physics." As early as 1962, Swiss physicist Georg Busch founded in West Germany a physics journal published by Springer titled Physik der Kondensierten Materie (Physics of Condensed Matter)［27］. In October 1963, the renowned physics journal Physical Review, affiliated with the American Physical Society, announced that it would introduce two separate thematic sections starting the following year. By 1970, these sections were formally separated, one of which was primarily dedicated to the study of atomic, molecular, and condensed matter physics［27-28］. In April 1978, a vote at the American Physical Society’s Council meeting resulted in a 15-to-7 decision to officially rename its "Division of Solid State Physics" as the "Division of Condensed Matter Physics"［27］, marking the physics community’s conceptual recognition of a universal theoretical framework and research paradigm applicable to all forms of condensed matter.
The establishment of condensed matter physics itself embodies the profound integration of physics and chemistry. Although it is commonly believed that chemistry is built upon the laws of physics, historically, many of the early key explorations of condensed matter phenomena—such as phase transitions and electrochemistry—were carried out by chemists. In fact, physics and chemistry are mutually dependent and mutually supportive. In contemporary science, disciplinary boundaries are becoming increasingly blurred, and the resolution of major scientific problems increasingly relies on interdisciplinary perspectives.
The core of chemical research lies in chemical reactions—an inherently dynamic process involving the transformation of matter and changes in energy. However, no chemical reaction occurs in isolation; rather, it is deeply embedded within its condensed-phase environment (such as solvents, catalysts, interfaces, etc.). Traditional chemical research, including its subdiscipline "solid-state chemistry," has often focused primarily on the static structures and properties of reactants and products. In reality, electric fields, magnetic fields, stress fields, solvent molecules, and catalyst architectures within the reaction environment all undergo dynamic evolution during the course of a reaction, profoundly influencing the reaction pathway, selectivity, and yield. Heterogeneous catalysis serves as a quintessential example: the reaction not only takes place on the surface of a solid catalyst but is also dynamically regulated by the microenvironment surrounding the active sites. This complexity can no longer be simply described using the language of traditional synthetic chemistry or catalysis alone.
In this context, in order to promote a fundamental conceptual revolution in the field of chemistry, Mr. Xu Ruren foresightedly proposed the academic idea of establishing the discipline of "Condensed-Phase Chemistry," advocating that chemical problems be examined within the overarching framework of condensed phases［29-32］. The core of condensed-phase chemistry lies in focusing on "chemical reactions influenced by multi-level structures," and its important sub-discipline—condensed-phase structural chemistry—should particularly be given due attention. In traditional structural chemistry education and research, the primary focus has been on the geometric and electronic configurations of isolated molecules and crystals, as well as the resulting physical manifestations (such as the interpretation of various spectra). This has led to structural chemistry being perceived more as the study of "the structure of chemistry," with some undergraduate students even considering it closer to physics and mathematics. Within the framework of condensed-phase chemistry, however, chemical research centers on reactions and their dynamic processes rather than on isolated, static systems. With the remarkable advances in in situ characterization techniques, it has been directly demonstrated that although the structures surrounding catalyst surface/interface active sites do not directly participate in the reaction, changes in their configurations can induce dynamic alterations in the local microenvironment properties around these active sites, thereby influencing the course of chemical reactions. Consequently, the focal point of condensed-phase structural chemistry should be placed on the dynamic evolution of the material structure within the reaction system under reaction conditions and its impact on reaction selectivity and final yield.
Traditional structural chemistry primarily focuses on the static geometry and electronic configurations of isolated molecules or ideal crystals. In contrast, condensed-phase structural chemistry shifts its focus to dynamic, multi-level reaction systems. It emphasizes that, under real reaction conditions, the dynamic evolution of non-reactive structures—such as catalyst surfaces and solvent shells—can induce local microenvironment property changes that play a decisive role in the course of chemical reactions.
Therefore, the research focus of condensed-phase structural chemistry lies in: under realistic reaction conditions, the multi-level dynamic evolution process of the system's material structure, and its regulatory mechanisms on chemical reaction selectivity and yield.
Compared with traditional structural chemistry, its core differences are manifested in three dimensions: (1) the multilevel nature of structure—ranging from atomic and molecular scales to mesoscopic and macroscopic levels—with a focus on cross-scale structural correlations; (2) the dynamic evolution of processes—using in situ characterization methods to study real-time structural changes during reaction processes; and (3) the decisive influence of the environment—highlighting the central regulatory role of the microenvironment (fields, solvents, interfaces, etc.) on reaction behavior.
This paper aims to take chemical reactions in solid-state systems as an example to introduce several typical condensed-phase structural factors, and to provide a prospective outlook on the application prospects of recent physical phenomena in condensed matter physics within the field of chemistry. The goal is to elucidate the essential principles and significance of condensed-phase structural chemistry, thereby laying a conceptual foundation for the development of this emerging interdisciplinary field.
2 The Condensed Phase in Chemical Reaction Systems
Condensed matter physics has undergone rapid development and achieved remarkable accomplishments over the past several decades. Quantum mechanics, as the cornerstone of condensed matter physics, provides a powerful theoretical framework for understanding the behavior of matter at the microscopic scale. However, when attempting to directly apply these fundamental physical theories—originating from idealized models such as isolated atoms, molecules, or perfect crystals—to complex chemical reaction systems, their applicability and predictive power often encounter severe challenges. This does not constitute a "failure" of the theory itself; rather, it stems from the fundamental differences between condensed matter physics and condensed matter chemistry in terms of their research objects and core paradigms.
The theoretical advantages of condensed matter physics lie in its ability to handle highly ordered systems or those that can be corrected by perturbation theory. Its research paradigm tends to "simplify the complex" by abstraction and reduction, stripping away secondary factors to capture the core physical laws governing system behavior. In contrast, the vast majority of chemical reactions do not occur in such pure systems. By nature, a chemical reaction is a dynamic, multi-factor coupled complex system, in which the state of matter, phase interfaces, solvents, dispersants, and even local fields in the environment all act as active participants, collectively determining the reaction process and its direction.
This difference is rooted in the divergent research objectives of the two disciplines: physics seeks to uncover universal natural laws, whereas chemistry is dedicated to the creation and manipulation of matter. Consequently, chemists place greater emphasis on "simplifying complexity" in their research—actively introducing and leveraging a variety of controllable variables (such as catalysts, additives, solvent systems, external fields, etc.) in order to achieve precise, deliberate control over reaction pathways, rates, and selectivity.
It is precisely based on a profound understanding of the complexity of chemical reactions and the pursuit of precise regulation that the concept of condensed-phase structural chemistry has emerged. Adhering to this core idea, this chapter will systematically analyze, through specific examples, how key condensed-phase factors—such as interfacial effects, electrostatic/magnetic fields, the microenvironment of active sites, and light fields (electromagnetic alternating fields)—play their dynamic regulatory roles during chemical reactions.
2.1 Dynamic Interface Structure in the Reaction
According to the aggregation states of matter, interfacial chemical reactions can be broadly classified into six types: solid–gas, solid–liquid, solid–solid, liquid–liquid, liquid–gas, and gas–gas. Considering the scope of condensed-phase chemistry and the focus of this special issue, this article will concentrate on the first three categories—namely, surface/interface reaction systems centered on solid-state materials. Solid surfaces/interfaces are ubiquitous in both natural and artificial systems, and their structural complexity forms the foundation for understanding their chemical behavior. This complexity is not only manifested in the microscopic arrangement of atoms and molecules but also in higher-level structures known as “phases,” which are determined by different thermodynamic conditions. For example, SiO2, a single compound, has been confirmed to exhibit as many as 14 crystalline phases, including its two-dimensional forms［33-34］. The crystalline phase structure of solid materials largely determines their intrinsic physical and chemical properties.
However, the traditional static understanding of solid surface/interface structures is being overturned. An increasing body of evidence indicates that solid surfaces/interfaces are far from being silent bystanders in chemical reactions; instead, they undergo profound dynamic evolution as the reaction proceeds. In typical catalytic reactions, these dynamic evolutions can manifest at multiple levels: changes in the catalyst’s macroscopic morphology and nanoparticle size, adjustments in the coordination number and electronic structure of active sites, and even the reconstruction of the support or substrate material’s structure. Based on whether they can revert to their original state after the reaction ceases, these evolutionary processes can be further classified into reversible and irreversible categories. Figure 1Taking the electrocatalytic hydrogen evolution reaction as an example, several typical reversible and irreversible dynamic surface structural evolution modes are illustrated［35］.
2.1.1 Solid–Gas Interface Reaction
At the solid–gas interface, the first step is typically the adsorption of gas molecules onto the solid surface. Depending on the properties of the solid surface and the gas molecules, adsorption behavior can be broadly classified into physical adsorption, chemical adsorption, and a hybrid form known as physicochemical adsorption. In studies of interfacial chemical reactions, physical adsorption with relatively weak adsorption energies is usually not considered. Theoretical investigations have long indicated that upon exposure to the bulk phase, the surface atomic layers of a crystal undergo relaxation. This relaxation phenomenon is particularly pronounced at sites with lower coordination numbers, such as step edges and defect sites. Furthermore, when strong chemical adsorption occurs, the adsorbed species exert a significant inductive effect on the atoms near the adsorption site, leading to structural rearrangements of the surface. Such structural changes generally occur on time scales comparable to those of the corresponding chemical processes. Experimental studies conducted as early as the 1990s have demonstrated a close correlation between surface reconstruction capability and reactivity［36-38］. In 1996, experiments clearly observed that after sulfur atoms were adsorbed onto a Pt(111) surface and the sample was annealed at 600 ℃ for 30 seconds, a double-layered stepped Pt structure as shown in Figure 2a was formed［39］. However, under ambient-temperature conditions, concurrent adsorption of sulfur and carbon monoxide on the Pt(111) surface resulted in structural rearrangements: as illustrated in Figure 2b, the height of the Pt steps decreased to a single atomic layer, with sulfur and carbon monoxide alternatingly adsorbed on the step terraces. Interestingly, upon reheating to 600 ℃, the Pt(111) surface reverted to its original double-layered stepped configuration. This study provided a clear visual representation of the interplay between chemisorbates and the surface morphology of the adsorbent. With advancements in experimental techniques, the same research group later reported, 14 years after their initial findings, that the periodic stepped structure of a Pt(557) surface underwent significant restructuring as the CO coverage varied［40］. In Figure 2c, one can see the pristine stepped surface morphology of Pt(557) under ultrahigh-vacuum conditions (vacuum level 1 × 10-10 torr, where 1 torr equals 133.3224 Pa). Upon introducing a small amount of CO gas into the system (at a vacuum level of 5 × 10-8 torr), noticeable changes began to appear in the surface structure: the number of steps decreased, and a wavy pattern emerged, as depicted in Figure 2d. When the CO pressure was further increased to 1 torr, as shown in Figures 2e and f, the stepped morphology completely disappeared, giving way to triangular Pt nanoparticles approximately 2.2 nm in size. The authors suggested that this fragmentation of the surface into nanoclusters represents a structural rearrangement aimed at alleviating repulsive interactions among neighboring CO molecules and thereby reducing the surface energy. Notably, the study also pointed out that under identical conditions, the structural rearrangements observed on a Pt(332) surface differed markedly. These findings clearly demonstrate that the structure of solid–gas interfaces is highly susceptible to influences from factors such as gas composition, concentration, and reaction type, undergoing continuous dynamic evolution during the course of a reaction. An increasing body of experimental evidence strongly supports this conclusion［41-44］.
Graphene is undoubtedly one of the most popular research areas in the first two decades of the 21st century. During the synthesis of graphene on transition-metal surfaces via chemical vapor deposition (CVD), the dynamic evolution of the metal–hydrocarbon gas interface structure can be observed. The interaction between transition-metal surfaces and carbon atoms had already attracted considerable attention even before the graphene boom ［45-46］. Under high-temperature conditions, carbon atoms can dissolve into the bulk of the transition metal, forming a solid solution. Depending on the solubility of carbon atoms within the transition metal, CVD-synthesized graphene can be classified into two growth modes: decomposition growth and surface-segregation growth ［47］, with Cu and Ni serving as typical catalytic metals, respectively. At a high temperature of 1000 ℃, the solubility of carbon atoms on the Cu surface is approximately 0.04% (atomic fraction), whereas on the Ni surface it reaches as high as 2.03% (atomic fraction) ［48-49］.
On the Cu(111) surface, hydrocarbon gas molecules (typically methane, ethane, methanol, etc.) serve as carbon sources and undergo catalytic decomposition and dehydrogenation. The released carbon atoms diffuse across the surface, nucleate, and grow to ultimately form high-quality monolayer graphene［50］. In stark contrast is the graphene synthesis process on the Ni surface. Due to Ni’s high solubility for carbon, carbon atoms decomposed at elevated temperatures can penetrate into the Ni bulk, forming a metastable Ni–C solid solution. As the temperature decreases, the solubility of carbon atoms in the Ni metal diminishes, leading to their segregation and driving the epitaxial growth of graphene on the Ni(111) surface［51］. The results of computer dynamics simulations shown in Figure 3clearly illustrate the precipitation of carbon from the Ni3C crystal and the subsequent nucleation of graphene on the surface. It can be observed that as carbon atoms continue to precipitate, some Ni atoms are also pulled toward the surface, creating space for deeper-lying carbon atoms within the crystal to migrate outward. Ni atoms and the precipitated surface carbon atoms form Ni–C n -Ni bridging structures via σ bonds, thereby stabilizing the polyacetylene chains on the Ni surface. Further theoretical studies have indicated that the formation of the surface carbon network is primarily attributed to the mobility of Ni atoms［52］. This dynamic structural transformation at the metal–gas interface during high-temperature reactions constitutes a central issue in condensed-phase structural chemistry research.
2.1.2 Solid–Liquid Interface Reaction
The solid–liquid interface is extremely common in both natural and technological contexts, and the chemical reactions occurring at this interface are well known. Examples include corrosion of metals in salt solutions, dissolution of salt crystal surfaces, crystallization and precipitation of ionic crystals in supersaturated solutions, as well as electrocatalytic reactions in electrolyte solutions. These common chemical reactions are all accompanied by dynamic evolution of the interfacial structure, rather than being static processes. The dynamic changes in the solid–liquid interfacial structure significantly influence the reaction kinetics. Due to the strong long-range mobility of the liquid near the solid–liquid interface, the structure of the liquid phase close to the interface is constantly undergoing dynamic changes, a phenomenon that is readily observable. Therefore, this paper focuses on the dynamic behavior of the solid phase side, particularly the solid surface in contact with the liquid phase. The dynamic changes in the liquid-phase structure, which are attributed to interfacial microenvironmental factors, will be briefly discussed later.
Corrosion is a phenomenon in which the surface of a material deteriorates due to interactions with its environment, commonly observed on metal surfaces exposed to aqueous solutions. This complex electrochemical reaction process leads to dynamic changes in both the surface morphology and chemical composition of the metal. Taking localized corrosion (pitting corrosion) of carbon steel in NaCl solution as an example, the process typically proceeds through three stages: the induction period, the propagation period, and the saturation period［53］. The presence of Cl-at the interface initially disrupts the oxide film on the metal surface, creating defect sites and initiating subsequent reactions. During the propagation period, the growth rate of corrosion pits accelerates significantly; once the pits are widely distributed, the corrosion rate approaches saturation. Subsequently, due to surface passivation and diffusion limitations, the pit growth rate decreases over time. Intrinsic defects on the metal surface, surface stresses, and the chemical composition of the solution all have a significant impact on the corrosion process. Additionally, the corrosion products formed—such as FeOOH on carbon steel surfaces and Fe3O4, Cr2O3, and NiO on stainless steel surfaces—dynamically alter the interfacial morphology, further influencing the corrosion rate. During corrosion, metal cations diffuse through the hydrogel layer and couple with the precipitation of metal hydroxides, giving rise to chemical waves driven by solution feedback mechanisms. These waves result in periodically aggregated patterns of corrosion products［54］.
A continuous dynamic interface forms between the crystal and its solution, where solute molecules constantly attach to or detach from the crystal surface, driving either crystal growth or dissolution. The mechanisms of crystal growth include step-flow, spiral growth, and two-dimensional nucleation, all of which are highly dependent on the supersaturation of the solution. At low supersaturation levels, the crystal surface grows in a stepwise manner; whereas under higher supersaturation conditions, dislocations readily form on the crystal surface, thereby inducing spiral growth and two-dimensional nucleation［55-56］. As the reverse process of crystal growth, crystal dissolution exhibits nonlinear characteristics, with its rate being time- and space-dependent. The morphology of the crystal surface, particularly defects, can trigger an initial rapid dissolution; as more stable subsurface layers are exposed, surface activity decreases, leading to a gradual reduction in the dissolution rate until it stabilizes. The dissolution rate is also strongly influenced by the dynamic saturation of the solution at the interface. The stepwave model explains the pulsed mass transport and the critical role of lattice defects in driving dissolution［57］.
Many catalytic reactions occur at the solid–liquid interface. Solid catalysts in the liquid phase typically undergo dynamic changes in surface structure and composition, which significantly affect catalytic activity and reaction selectivity［58］. Therefore, elucidating the dynamic evolution of the interfacial structure is crucial for determining the active surface structure of the catalyst. In electrocatalytic water splitting for oxygen evolution reaction (OER), metals, metal oxides, or sulfides are commonly used as catalysts［59-60］; however, it is the oxides, hydroxides, and oxyhydroxides formed after surface reconstruction that serve as the true active sites［61］. During the reaction, the migration of certain specific elements within the solid catalyst drives surface reconstruction, thereby altering its catalytic performance. Taking SrIrO3 perovskite material in the electrocatalytic OER reaction as an example, as shown in Figure 4a–c, Sr2+ ions gradually migrate (dissolve) into the solvent over time, while O2− ions induce surface reconstruction, resulting in the formation of an amorphous layer［62］. In the OER reaction using NiCo bimetallic fluoride as the electrocatalyst, the migration of fluorine atoms leads to surface reconstruction, generating more surface-active sites and increasing the electrochemical active surface area［63］. Iron can substantially enhance the catalytic activity of Ni(oxides/hydroxides) in the OER reaction. When Fe3+ cations are present in the electrolyte, the surface of the NiO electrocatalyst combines with them to form layered NiFe double hydroxides, as illustrated in Figure 4d. However, with the prolongation of the reaction time, the additional accumulation of FeO x on the surface will reduce the catalytic activity［64］.
Currently, the academic community has recognized that understanding the structure of catalyst materials—particularly the relationships among structure, composition, and surface reconstruction—is crucial for designing efficient catalytic reaction systems. Gaining insight into transient amorphous phases and defect structures that may exist at the interface, as well as elucidating the dynamic formation and evolution mechanisms of surface active sites, holds significant importance for heterogeneous catalysis.
2.1.3 Solid–Solid Interface Reaction
Chemical reactions at solid-state interfaces underpin a variety of phenomena, including sintering, diffusion bonding, phase transformations, and corrosion. These reactions are of great significance for the design of high-performance functional materials, the enhancement of technological efficiency, and the improvement of material durability. Understanding and controlling solid-state interfacial reactions constitute a key research topic in materials science. Solid-state interfacial chemical reactions typically involve chemical interactions between two or more solid-phase materials at their contact interfaces, with mechanochemical reactions serving as a paradigmatic example. According to the definition provided by the International Union of Pure and Applied Chemistry (IUPAC), a mechanochemical reaction is one that is directly initiated by the absorption of mechanical energy［65］. Common methods include grinding, ball milling, and ultrasonic treatment. By applying impact, shear, or friction, these techniques supply the reactants with the energy required to surmount activation barriers, thereby facilitating chemical transformations. As early as 1820, Michael Faraday successfully displaced elemental silver from a mixture of AgCl and Zn through “dry” grinding, thereby demonstrating the feasibility of mechanically induced chemical reactions［66］.
The mechanisms by which mechanical energy promotes solid-state interfacial reactions mainly include the following aspects: (1) reducing the particle size of reactants, increasing the specific surface area, and enhancing the probability of contact between reactants, thereby accelerating the reaction rate; (2) introducing lattice defects to elevate site energies, creating highly active reaction sites, and improving overall reactivity; (3) inducing amorphization on the surfaces of crystalline reactants, lowering the reaction energy barrier, and further enhancing reactivity. As shown in Figure 5a, during a mechanochemical reaction, reactants undergo elastic deformation under mechanical energy and subsequently enter an inelastic deformation state (such as phase transformation, amorphization, or defect formation). Ultimately, they are activated, overcome the reaction energy barrier, and undergo chemical reactions, including covalent bond cleavage and formation, proton or electron transfer at the interface, and accelerated polymerization or decomposition reactions. For molecular crystals, reactions can be categorized into two types: those occurring within the solid and those occurring between solids (Figure 5b). Furthermore, organic molecular crystals and inorganic ionic crystals can form solid solutions, supramolecular crystals, or eutectics through mechanical grinding. As illustrated in Figure 5c, mechanical grinding of an organometallic zwitterionic crystal together with an alkali metal crystal facilitates the embedding of alkali metal cations and halide anions between [CoIII(η5‐C5H4COOH)(η5‐C5H4COO)] molecules under the action of mechanical energy, thereby forming a supramolecular complex crystal structure. Essentially, the mechanochemical process is highly consistent with the principles of condensed-phase structural chemistry. The reaction progress is driven and regulated by the dynamic evolution of material structures, reflecting the intrinsic relationship between structure and function.
All-solid-state batteries are considered an ideal system for achieving high-performance battery goals due to their superior performance and safety. Their core feature lies in the adoption of solid-state electrolytes in place of traditional liquid electrolytes. As shown in Figure 6, all-solid-state batteries contain multiple solid–solid interfaces, including the metal anode–electrolyte interface, electrolyte–electrolyte interface, cathode–electrolyte interface, and conductive additive–electrolyte interface. Chemical reactions primarily occur at the following four types of interfaces: cathode–electrolyte, anode–electrolyte, conductive filler–electrolyte, and cathode current collector–electrolyte. Interfacial resistance is a key factor limiting the performance of all-solid-state batteries, and it is closely related to the complex chemical reactions occurring at these interfaces. Therefore, in-depth investigation of these interfacial chemical reactions is crucial for optimizing battery performance.
Taking the interface between the lithium metal anode and the solid-state electrolyte as an example, as shown in Figure 6b, significant differences in the interfacial state (including both structural and stress states) markedly influence the migration behavior of lithium. These varying migration behaviors subsequently lead to different degrees of dendrite growth within the electrolyte (Figure 6c). Similarly, cathode materials also undergo dynamic structural evolution during charge–discharge cycling. As illustrated in Figure 6d, after 300 cycles, cobalt atoms in the c-LiCoO2cathode material are observed to have diffused significantly into the cathode surface layer, reflecting the dynamic nature of interfacial chemistry.
In heterogeneous catalysis, solid–solid interfaces often serve as catalytic active sites. Precise structural control at the nanoscale or even atomic scale directly influences catalytic performance and is central to large-scale industrial catalytic processes［71］. The structure and composition of solid-state heterojunction catalysts determine the system’s catalytic activity and reaction mechanism. Taking Pt nanoparticles catalyzing CO oxidation to CO2as an example (Figure 7), when Pt nanoparticles are supported on an inert material, their surfaces become fully covered by CO molecules at low temperatures, making it difficult to activate O2and thus preventing effective catalysis of the CO oxidation reaction. To simultaneously activate both CO and O2, the temperature typically needs to be raised above 200 ℃, which induces partial desorption of CO molecules adsorbed on the Pt nanoparticles, thereby creating active sites for O2adsorption and activation. However, if the support material is replaced with CeO2crystals capable of activating O2molecules, the Pt nanoparticles and the CeO2crystal surface can respectively facilitate the activation of CO and O2molecules, significantly enhancing low-temperature catalytic performance［72］. By tuning the heterojunction interface structure, it is possible to effectively control the formation and strength of the Schottky barrier, promote the separation of different types of charge carriers, and potentially enhance piezoelectric catalytic activity［72］.
Solid-state heterogeneous junction catalyst interfaces undergo dynamic structural evolution during the reaction process. Taking the interface composed of Cu and other metals as an example, it can significantly enhance the selectivity toward multi-carbon compounds in the electrocatalytic CO2 reduction (CO2R) reaction. The Au–Cu bimetallic system (where Au nanoparticles are epitaxially grown on the Cu surface) serves as a typical model for studying the electrocatalytic CO2R to produce multi-carbon alcohols. According to conventional theory, the Au surface first reduces CO2 to *CO, leading to a high concentration of *CO and subsequent dimerization, after which high-value target products are formed on the Cu surface. However, energy-dispersive X-ray spectroscopy (EDS) analysis reveals that the Au–Cu interfacial structure is not static. During the reaction, Cu vacancies and Cu ions continuously form near the interface and can dynamically migrate, causing the initially well-defined bimetallic interface to gradually evolve into an Au@Cu core–shell nano-cluster structure supported by an Au–Cu alloy layer［73］. Specifically, Cu(0) is first oxidized to Cu(I) and Cu(II), introducing oxygen atoms into the surface lattice and disrupting the local atomic configuration. Under applied bias, Cu(I) and Cu(II) are reduced back to Cu(0), thereby generating atomic vacancies nearby. These vacancies facilitate the mutual diffusion of Cu and Au atoms, resulting in the formation of an Au–Cu alloy layer. Due to the relatively low adsorption energy of the Au nanoparticle surface, Cu ions from the electrolyte readily deposit onto it, forming the Au@Cu core–shell structure. This dynamic reconstruction, driven by the oxidation/reduction cycles of Cu(0), fundamentally challenges the traditional understanding of the reaction mechanism: the Au clusters encapsulated within the Cu shell are unlikely to directly activate CO2 molecules to generate *CO. A more plausible mechanism is that *CO is generated on the Au–Cu alloy layer, desorbs thereafter, and migrates to the Cu shell surrounding the clusters, ultimately being converted into ethanol on the Cu shell. This revised mechanism aligns with the core tenets of condensed-phase structural chemistry, which emphasize that dynamic structural evolution governs the reaction pathway. Similarly, another study focusing on the electrocatalytic CO2R using Cu68Ag32 nanowires has also observed dynamic surface structural evolution and the formation of an alloy layer［74］.
Recent studies have shown that in the electrocatalytic CO2R reaction for producing high-value multi-carbon alcohol products, the unique 4f electron orbitals and unoccupied 5d orbitals of the rare earth element Pr can be utilized to regulate the electron density distribution of neighboring Cu atoms. Through the synergistic effect of Pr–O–Cu bonds, the valence state of Cu can be dynamically modulated between 0 and +2, while a self-healing stable heterojunction interface is formed［75］. Researchers employed in situ X-ray emission spectroscopy (XES) to reveal the stepwise changes in the valence state of Cu during the reaction process. These findings further substantiate the importance of condensed-phase structural chemistry in catalysis research.
With advances in research techniques, evidence in condensed-phase structural chemistry has been continuously enriched. Currently, the primary methods for studying the dynamic evolution of structures under reaction conditions include theoretical simulations and In-situ characterizations. Theoretical simulations simplify reaction conditions to predict and analyze the microscopic geometric and electronic structural evolution of reaction systems over short time scales. As computational power increases, research has shifted from static structural simulations to in-depth analyses of dynamic reaction processes, aiming to closely approximate experimental conditions. For example, first-principles molecular dynamics (AIMD) simulations of the Au/TiO2 nanosystem at 700 K, as shown in Figure 8, reveal that Ti interstitial defects in TiO2 tend to migrate into Au clusters rather than precipitate on the surface and be oxidized by O2 to form new TiO2 islands［76］. However, theoretical simulations are constrained by computational limitations, resulting in relatively small model sizes (typically containing up to 103 atoms) and short simulation timescales (on the order of 102 ps), which make it difficult to fully capture the dynamic behavior of complex systems. To address these challenges, theoretical researchers have continually developed various novel approaches, such as density functional-based tight-binding methods (DFTB), quantum mechanics/molecular mechanics hybrid methods (QM/MM), reactive force fields (ReaxFF), and machine learning (ML). It is anticipated that future breakthroughs in computational hardware and software—particularly in AI4Science—will enable chemical reaction simulations that more closely resemble real-world conditions, thereby fundamentally enhancing our understanding and design of chemical reactions.
The development of in-situ characterization techniques has provided a powerful tool for real-time detection of dynamic structural evolution during reaction processes. In particular, operando characterizations, by integrating structural characterization with measurements of catalytic activity and selectivity, have significantly enhanced analytical accuracy［77］. In-situ characterization techniques can be broadly classified into two major categories: optical techniques and spectroscopic techniques. In-situ optical techniques directly reveal the evolution of the catalyst's geometric configuration during the reaction, while in-situ spectroscopic techniques indirectly obtain information on structural evolution by analyzing changes in oxidation states, coordination numbers, and other parameters. However, current in-situ characterization techniques still face limitations; for instance, they are often unsuitable for reaction systems under more demanding conditions such as irradiation, high-temperature melting, ultra-high pressure, or strong magnetic fields. Furthermore, limitations in signal acquisition speed, measurement accuracy, and the complexity of data processing restrict their widespread application. To overcome these challenges, researchers are dedicated to developing more advanced in-situ characterization techniques and employing combined multi-technique approaches in order to achieve a more comprehensive understanding of chemical reaction mechanisms［77-79］.
Advances in theoretical simulation and in situ characterization have demonstrated that the field of heterogeneous catalysis has come to a profound understanding of the decisive influence of dynamic structural evolution on catalytic performance［80-84］. Therefore, integrating this research perspective into the broader chemical sciences and emphasizing the theoretical frameworks of condensed-phase chemistry and condensed-phase structural chemistry is not only of great significance but also timely.
2.2 External Electric Field
The electric field is a fundamental concept in physics. Under its influence, condensed matter systems often exhibit unique physical behaviors and chemical phenomena. In chemical systems such as batteries and electrocatalysis, the effect of an external electric field is particularly significant. From a microscopic perspective, chemical reaction sites are situated in a transient and dynamic dielectric environment due to the dynamic changes in the composition and configuration of surrounding materials, and they are subject to the action of reaction fields, built-in fields, induced fields, or piezoelectric fields. This paper focuses on the influence of the external electric field on chemical reactions, incorporating the discussion of transient electric fields at the microscopic scale into the subsequent section on the microenvironment.
As early as the 1930s, Lars Onsager, a Norwegian-American physical chemist and theoretical physicist, developed a mathematical model to describe the recombination of initially separated ion pairs under the influence of Coulomb interactions and an external electric field, using the diffusion equation. He derived an expression for the probability of escape recombination of ion pairs［85］. Subsequent studies revealed that, under high-intensity external electric fields, ion pairs in electrolytes exhibit an inverse-temperature effect: the probability of escape recombination decreases with increasing temperature［86］, providing early theoretical insights for condensed-phase chemistry research. In recent years, external electric fields have regained attention as a novel means of regulating chemical reactions. Parameters such as the strength, direction, and frequency of the external electric field directly affect molecular configurations, geometric arrangements, and electronic structures within condensed-phase systems, thereby modulating reaction activity and promoting, inhibiting, or inducing chemical reactions. A typical example is that an externally applied electric field oriented along a specific direction can alter the properties of chemical bonds, even triggering bond cleavage and rearrangement. When the direction of the external electric field aligns with or opposes the direction of electron redistribution during the conversion from reactants to products (i.e., the reaction axis), it can respectively catalyze or inhibit the reaction and may induce a transition from a concerted reaction mechanism to a stepwise mechanism. Furthermore, by enhancing charge-separation resonance, external electric fields can stabilize both the molecular structure of covalent compounds and their transition-state structures, significantly lowering the activation energy barrier［87-88］. The directional electrostatic field generated at the tip of a scanning tunneling microscope (STM) probe can accelerate Diels–Alder reactions. This experimental demonstration was the first to verify the regulation of non-redox bond formation by external electric fields, directly confirming the feasibility of manipulating the kinetics and thermodynamics of chemical reactions through external electric fields and offering new perspectives for multiphase catalysis［89］. Recent studies have shown that STM-controlled external electric fields can increase the rate of Diels–Alder reactions by more than threefold without affecting the reverse reaction rate, highlighting the potential of electric fields to selectively control reaction pathways［90］. In addition, the same STM-controlled external electric field can also be employed for electron-catalyzed single-molecule dehydrogenation reactions. Researchers have utilized the electric field between electrodes in an STM to drive electron transfer, thereby initiating an electron-catalyzed single-molecule dragging reaction involving the transformation of 1,2-bis(4-pyridinium)ethane (DPA2+) into 1,2-bis(4-pyridinium)ethylene (DPE2+)［91］(Figure 9).
From a quantum mechanical perspective, an external electric field regulates the formation of non-redox chemical bonds by inducing orbital hybridization. Taking the hydrogen atom as an example, when the principal quantum number n = 2, the four degenerate energy levels are orthogonal due to symmetry and thus incapable of hybridizing in the absence of an external field. However, applying an external electric field along the z axis triggers the Stark effect, resulting in energy-split 2s±2pz hybrid orbitals［92］, as illustrated in Figure 10. This mechanism can break the symmetry-forbidden nature of orbital hybridization, thereby enabling reactions that violate the Woodward–Hoffmann rules or front-side nucleophilic displacement reactions［93-94］. Furthermore, the external electric field can modulate reaction spin selectivity by stabilizing specific spin states of the transition state; its direction and application method are critical factors in controlling stereoselectivity and reactivity［95-96］. Therefore, as a versatile tool, the external electric field holds considerable potential for applications in fine chemical synthesis.
In photocatalytic systems, the promotion of positive/negative charge (carrier) separation by an external electric field is particularly important and constitutes one of the key strategies for achieving efficient solar energy conversion. During photocatalysis, the recombination of photogenerated carriers reduces both the utilization efficiency of photon energy and catalytic performance. Applying an appropriate external electric field can flexibly modulate the electronic structure of semiconductor materials, induce dipole polarization, alter local geometric configurations, or introduce localized stress［97-98］, thereby influencing photon absorption, valence electron excitation, and reaction activity through changes in the band gap and band edge positions［99-100］. As shown in Figure 11, the band gap and band edge positions of two-dimensional van der Waals heterojunction photocatalysts undergo significant alterations under the influence of an external electric field. Furthermore, the external electric field can modify the optical absorption edge of semiconductor materials and cause corresponding changes in their refractive indices; under strong electric fields, it may even trigger the Franz–Keldysh effect, enabling electrons to absorb photons with energies below the bandgap and become excited, although this effect typically requires high voltages (on the order of hundreds of volts) and is relatively rare in chemical reactions. For molecular systems with a pronounced dipole moment (such as liquid-phase systems), an external electric field can alter the phase transition critical temperature or induce chain-like self-assembly behavior［101］. However, the definition of the external electric field must take into account the dielectric environment of the actual reaction apparatus, as different dielectric conditions may lead to markedly contrasting system behaviors［102-103］.
Recent electrochemical studies have shown that pulsed electric fields can significantly enhance reaction efficiency and selectivity by periodically modulating the charge distribution within catalytic or inhibitory systems. For example, dynamic regulation of asymmetric charge distribution can improve C–N coupling efficiency［104-105］as well as the efficiency of carbon dioxide reduction reactions［106-107］. The multidimensional regulatory potential of external electric fields in chemical reactions has provided new theoretical and experimental directions for condensed-phase chemistry research.
2.3 Other External Fields
Except for the electric field, chemical reaction control often involves multiple external fields, including magnetic fields, temperature gradient fields, stress fields, and electromagnetic fields (light fields). Typically, most of these external fields are applied as vector fields along specific directions, which contrasts sharply with scalar control factors such as temperature and pressure. In practical reactions, these fields often act in a coupled manner to jointly influence the reaction process. This section focuses on the regulatory effects of single external magnetic fields, temperature gradient fields, stress fields, and electromagnetic fields on chemical reactions, providing a brief analysis through typical cases.
Although magnetic interactions are several orders of magnitude weaker than Coulombic interactions and are typically neglected in chemical reaction energy balances, the near-degenerate potential energy surface crossings induced by magnetic perturbations can have a significant impact on reaction rates, yields, and spectroscopic properties. In reactions involving electron spin (such as singlet–triplet transitions, particularly in transition metal systems), locally non-uniform magnetic fields can induce an exchange of spin-state phases, thereby modulating the reaction pathway. Given that the magnetic moment of an electron is much larger than that of a proton, the precession frequency difference between them becomes substantial under non-uniform magnetic fields, which in turn influences the reaction selectivity of long-lived excited-state radicals or radical pairs. An external magnetic field can regulate the population of spin states in nuclear–electron spin resonance, altering the angular momentum of radical pairs and thus achieving a magnetic catalytic effect［108］. In silicon isotopes, 29Si, which possesses a nuclear spin of 1/2, exhibits an oxidation rate more than twice that of non-magnetic isotopes due to the magnetic isotope effect, whereas there is virtually no difference in the oxidation rates among the non-magnetic Si isotopes. Secondary ion mass spectrometry analysis further confirms that an external magnetic field can accelerate the oxidation of solid Si crystals［109］. Moreover, the strength of the external magnetic field significantly affects the reaction yield. As shown in Figure 12, in the Pd@Co3［Co（CN）6］2-catalyzed Suzuki coupling reaction (the formation of diphenyl from bromobenzene and phenylboronic acid), the external magnetic field enhances the yield; however, this effect diminishes markedly with increasing temperature (up to 60 ℃), because the magnetic susceptibility of the paramagnetic Pd nanoparticles decreases as the temperature rises［110］.
Temperature, as a key factor in the regulation of chemical reactions, gives rise to significant temperature gradient fields in heterogeneous reaction systems due to the relative concentration of reaction sites. Artificially controlled temperature gradients can be achieved through techniques such as the traveling solvent floating zone method, thermal gradient chemical vapor infiltration, or temperature gradient colloidal electrophoresis. However, temperature gradients may lead to adverse effects, including non-uniform reaction rates, over-reactions, and uneven stress distributions; at the same time, they can also serve as a driving force for stabilizing reactions, regulating diffusion fluxes, and spatially localizing reactions. In fluid systems, temperature gradients drive extraction or non-equilibrium synthesis via free energy transfer. In non-equilibrium steady-state systems (such as biological cell metabolism or solar cells), temperature gradients maintain net fluxes and regulate kinetic behavior. For example, in perovskite materials, differences in thermal conductivity under illumination give rise to localized temperature gradients, thereby enhancing chemical instability. Even when the temperature remains well below the thermal decomposition threshold, these temperature gradients can induce the diffusion of extraneous species, accelerating the decomposition process［111］. Early theoretical studies on the relationship between temperature and semiconductor bandgaps, conducted by Varshni［112］, O’Donnell et al.［113］, and later by Lee et al.［114］, have demonstrated that changes in the semiconductor bandgap are not only temperature-dependent but are also influenced by strain and the coefficient of thermal expansion. During the gas–liquid–solid three-phase growth of nanowires, the introduction of a temperature gradient can regulate the growth direction. The temperature gradient drives the thermal diffusion of precursors toward the lower-temperature catalyst interface, where they aggregate and accelerate catalytic decomposition, increasing the liquid-phase chemical potential while disrupting interfacial stability and nucleation kinetics symmetry, thereby controlling the growth orientation of the nanowires (Figure 13)［115］. In integrated circuits, solder joints are not merely the result of physical processes; rather, they involve significant temperature gradients and chemical reactions that lead to the formation of intermetallic compounds at the interface. A research group has used synchrotron radiation imaging to meticulously observe the temporal evolution of intermetallic compound formation at both the cold and hot ends of Cu/Sn-9Zn/Cu solder joints under the influence of a temperature gradient. At the cold end, a distinct columnar Cu5Zn8compound is formed; subsequently, as zinc diffuses thermally along the temperature gradient and its concentration decreases, a Cu6(Sn, Zn)5compound emerges［116］.
The stress experienced by a material system can be divided into externally applied stress and internal local stress. Local stress is induced by temperature differences, defects, impurities, phonon-vibration coupling, and other factors, and it is closely related to the microenvironment of the reaction site. This section discusses only the externally applied stress field. External stress not only alters the geometry and electronic configuration of a material but also significantly influences its chemical properties due to the redistribution of electrons (within the elastic range, avoiding phase transitions, creep, or fracture). The stress field falls under the category of mechanochemistry, reflecting the coupling between mechanical energy and chemical reactions. From a theoretical perspective, strain leads to changes in interatomic distances and Coulombic interactions, thereby triggering adjustments in the electronic configuration and exerting a sensitive influence on chemical properties. For example, graphene can withstand elastic tensile strains exceeding 20%, which has given rise to the research field of "straintronics" ［117］. Tight-binding theory based on density functional theory has shown that biaxial tensile stress increases the bandgap width of graphdiyne from 0.47 eV to 1.39 eV, whereas uniaxial tensile stress has the opposite effect, reducing the bandgap and even leading to its closure ［118］. In 2D-MoS2, a biaxial tensile strain of 3.5% reduces the bandgap by approximately 0.35 eV and enhances light absorption capability ［119］, which is completely contrary to the behavior observed in graphdiyne. This difference is attributed to the distinct bonding and antibonding characteristics of orbitals as described by the Heitler–London exchange energy model ［120-121］. The bonding and antibonding energy levels are described by Equation (1)and Equation (2).
in the equation: Krepresents the classical Coulomb energy, which is used to describe the electron–electron and electron–ion interactions; Sdenotes the orbital overlap integral. Since Sis typically much less than 1, S2will naturally be even smaller. Therefore, as can be seen from the above two equations, the Hterm will play a decisive role in determining the shifts of bonding and antibonding energy levels under strain. As an exchange integral term, Hcan be expressed as Equation (3).
nonclassical electron-electron interactionsshould be positive, whereas electron-ion interactions should be negative. Different orbital types (s, p, etc.) lead to variations in the H term contributions, which account for the material’s differential response to strain. Furthermore, triangular-symmetry stress can induce a uniform pseudomagnetic field of approximately 10 Tesla in graphene, triggering Landau quantization, opening an energy band gap of about 0.1 eV, and giving rise to the quantum valley Hall effect［122-123］. First-principles calculations have shown that biaxial tensile stress can significantly enhance the electron-phonon coupling in doped graphene, thereby satisfying the phonon-mediated superconductivity requirements of the Bardeen-Cooper-Schrieffer theory［124］; although superconductivity research primarily falls within the domain of physics.
In the 1970s, Bell［125］proposed that a linear relationship might exist between mechanical stress and chemical reaction activity. As subsequent research deepened, theoretical analysis revealed that this relationship is not simply linear. Building upon Bell’s linear approximation, later researchers introduced nonlinear correction terms and derived an expression for the relationship between the activation energy (energy barrier) and stress (Equation (4)) ［126］.
in the equation: denotes the stress vector, and represents the Hessian matrix. The subscripts tsand 0 refer to the transition state and the potential energy minimum, respectively. According to classical transition state theory, in one dimension, the reaction rate associated with stress can be expressed as Equation (5).
for simple intermolecular reactions, the pre-exponential factor is related to the steady-state vibrational frequency. In condensed-phase systems, according to variational transition state theory, the pre-exponential factor must further incorporate a transmission factor to account for recrossing effects along the reaction pathway［127］. However, this model still fails to fully capture the complex influences of other factors in condensed-phase systems—such as the microenvironment and interfacial interactions—on chemical reactions.
The study of light–matter interactions began with Einstein’s elucidation of the photoelectric effect, which laid the foundation for photochemistry and spectroscopy. The interaction between molecules and specific light modes depends on the electronic structure and vibrational characteristics of the molecules. Traditionally, spectroscopic and photochemical studies have assumed that the incident alternating electromagnetic field is unaffected by the molecule or any factors other than the dielectric environment in its vicinity. However, recent research has shown that the environmental response to the incident electromagnetic wave can significantly alter the field effects experienced by the molecule, being markedly influenced by the structure and properties of the surrounding materials. Strong light–matter coupling can reach 1 eV, substantially affecting chemical reaction kinetics, particularly in organic molecular systems, where it leads to collective effects through the formation of polaritons and multi-molecule coherent interactions, thereby regulating reaction pathways［128-130］. As shown in Figure 14, light–matter coupling can induce singlet–triplet energy inversion that violates the classical Hund’s rule, thereby manipulating energy flow within molecular systems［131］. Strong coupling not only modifies excited-state energies but also perturbs ground-state equilibrium, consequently influencing molecular reaction rates, electrical conductivity, and excited-state relaxation pathways, thus providing a new approach for property modulation without altering molecular structure［129-130］.
Under strong electromagnetic wave irradiation conditions (such as cosmic rays or nuclear spent fuel processing), chemical reactions involve complex electron-electron, electron-nucleus, and nucleus-nucleus collisions, exhibiting behavior that differs significantly from conventional photochemistry［132］. It should be emphasized that chemical reactions are typically governed by the coupled effects of multiple external fields (stress fields, light fields, electric fields, etc.), rather than being dominated by a single external field. This multi-field synergy significantly enhances the ability to regulate reaction kinetics and selectivity, providing new theoretical and practical directions for condensed-phase chemistry research.
2.4 Microenvironment
Existing research has demonstrated that the dynamic structural evolution of a reaction site during a chemical reaction is significantly influenced by its surrounding microenvironment. Although the structural components within the microenvironment do not necessarily participate directly in the chemical reaction, their dynamic responses indirectly regulate the behavior of the reaction site, thereby affecting the overall reaction process［133-134］. In this paper, factors near the reaction site that do not directly participate in the reaction but influence reaction kinetics and selectivity are collectively referred to as the “microenvironment.” Due to space constraints, this section provides only a brief analysis of several typical microenvironmental factors (local built-in electric fields, pH distribution, dielectric shielding, and spatial confinement) to highlight the critical role of the microenvironment in chemical reactions.
Besides the external electric field, local structural design—such as heteroatom doping, functional group modification, or vacancy defect creation—can induce charge redistribution, thereby generating a short-range built-in electric field. Unlike the external electric field, the built-in electric field has a limited range of action and typically acts along the reaction axis or bond axis, significantly influencing the system’s band structure, Fermi level, carrier type, and transport rate. It optimizes processes such as the adsorption/desorption of reaction species and reduces the reaction energy barrier. Furthermore, the built-in electric field can regulate the concentration and species distribution near the reaction sites, promoting mass transfer and triggering coupled effects of microenvironmental factors. However, an inappropriate built-in electric field may hinder the reaction process. Early research on built-in electric fields primarily focused on the physical properties at semiconductor heterojunction interfaces. In the chemical domain, their applications are predominantly found in ion batteries, solar cells, photocatalytic systems, and electrocatalytic systems, mainly for tuning the band structure and enhancing charge carrier separation. For example, in a ZnO/Ni(OH)2 heterojunction photoanode, the piezoelectric effect–induced built-in electric field significantly affects the oxygen evolution reaction efficiency. A 0.2% tensile strain increases the current density by approximately 85%, whereas a 0.2% compressive strain decreases it by about 30%, reflecting the differential impact of the built-in electric field direction on reaction efficiency［135］. In electrocatalytic reaction systems, experimental observations have shown that the built-in electric field at the CuCl(111)/rutile-TiO2(110) heterojunction leads to the enrichment of NO3- at the interface, enabling the efficient conversion of ultra-low-concentration nitrates into ammonia. The built-in electric field lowers the energy of the intermediate *NO, reducing the activation energy of the rate-determining step and thereby enhancing the reaction conversion efficiency, resulting in an ammonia selectivity approaching 99%［136］.
Localized strain, defects, impurity atoms, and functional group adsorption can induce dynamic charge redistribution, thereby altering the distribution of species near the reaction site and causing fluctuations in local pH. pH regulation is a conventional approach for controlling chemical reaction processes; however, the dynamically changing pH near the reaction site throughout the reaction course has a more complex impact on chemical reactions. From a microscopic perspective, the consumption of acidic or basic substances during the reaction can lead to transient fluctuations in local pH. In photocatalytic or electrocatalytic CO2 reduction (CO2R) and water-splitting hydrogen evolution reactions, OH- ions are generated at the anode, resulting in an increase in pH near the photocatalyst or electrode［137］. According to the Nernst equation, there exists a linear relationship between redox potential and pH in both the overall CO2 reduction reaction and the water-splitting reaction［138］. Electrochemical reactions proceed more rapidly, leading to more pronounced pH fluctuations. In particular, in electrocatalytic CO2 reduction, experimental evidence has demonstrated that the local pH at the electrode surface directly influences reaction selectivity. Early experimental studies suggested that higher pH values favor the formation of dicarbon products［139］, whereas recent research indicates that lower pH values—characterized by elevated H+ ion concentrations—increase CO2 concentration near the cathode, thereby promoting the formation of CO or dicarbon products such as C2H4 and C2H5OH［140］. These seemingly contradictory experimental findings clearly highlight the intricate role of local pH in CO2R reactions, underscoring the urgent need for in-depth investigation that fully accounts for microenvironmental factors.
The local electric field or changes in species concentration within the microenvironment significantly affect the dielectric environment near the reaction site, particularly playing a prominent role in photocatalytic reactions. Studies have shown that the thickness of semiconductor materials directly influences their optical properties. For example, as the thickness of CdS nanofilms increases from 15.2 nm to 25.4 nm, their optical band gap decreases from 2.88 eV to 2.61 eV［141］. Many-body perturbation theory reveals that delocalized dielectric screening has a significant impact on the electronic structure of low-dimensional semiconductors. As the thickness of layered materials decreases, the quasiparticle band gap increases markedly. For instance, the quasiparticle band gap of 4-layer black phosphorus is approximately 0.63 eV, whereas it increases to 0.87 eV for a 3-layer system and further to 1.22 eV for a 2-layer system; for single-layer black phosphorus, the quasiparticle band gap has already risen to 2.08 eV［142］. The dielectric environment also affects the exciton binding energy［143］; typically, the exciton binding energy of monolayer materials is considerably larger than that of their bulk counterparts. When designing two-dimensional Janus materials (Ga2SO or InSO0.5), both the material’s own thickness and the thickness of the substrate material (such as wide-bandgap h-BN) can be used to tune the exciton binding energy by a substantial margin—approximately 200–250 meV. The results are illustrated in Figure 15. Experimentally, through dielectric environment engineering, the band gaps and exciton binding energies of monolayer WS2 and WSe2 can be modulated within a range of several hundred meV［144］.
The growth process of crystals is significantly influenced by spatial confinement in the surrounding environment, particularly within the pores of porous systems such as biological tissues or porous minerals. Biomimetic research controls crystal morphology and strength by regulating factors such as ion composition, pH value, and supersaturation. In nanoscale confined spaces, crystal growth kinetics are restricted, and two-dimensional mass transport of ions within the liquid film is governed by spatial gradients, which affect crystal surface morphology and growth rate, manifesting as features such as inclined spirals or localized nucleation［145］. Molecular dynamics simulations have shown that, in a supersaturated NaCl solution, Na+ions selectively adsorb at the metastable NaCl (001)/water interface; solvent polarization significantly influences ion distribution at polar interfaces, thereby regulating crystal growth［146］.
3 New Chemical Methods Driven by Novel Concepts in Condensed Matter Physics
Chemistry and physics differ fundamentally in their research perspectives and methodologies. Although condensed-phase chemistry does not need to strictly follow the advances of condensed-phase physics, emerging physical concepts and phenomena have provided new ideas for the development of chemistry. This section introduces several relatively new physical concepts that have already demonstrated application potential in chemical research. It is important to emphasize that the core of chemical research lies in reactions; applying condensed-phase physics concepts to chemical reactions represents an important direction in condensed-phase chemistry. Since new physical phenomena originate from material structures, exploring their roles in chemical reactions is one of the key tasks of condensed-phase structural chemistry.
3.1 Quantum Confinement Effect
Quantum confinement effects originate from quantum mechanics and describe the quantization of energy for electrons or electron–hole pairs (excitons) when the dimensions of a material approach or fall below the de Broglie wavelength (the matter wave wavelength). This quantization confines the energy to discrete levels, resulting in a non-continuous energy spectrum. Such phenomena are the fundamental reason why nanomaterials exhibit physical properties distinct from those of bulk materials. In the 1990s, nanoscale metal or semiconductor clusters attracted chemists’ attention due to the unique properties of their delocalized valence electrons［147］. In chemical research, even for relatively large systems, surface atoms differ in behavior from bulk atoms because of their distinct coordination numbers. As the size decreases and the spatial dimension reduces, minor changes in geometric configuration can significantly influence electronic properties and environmental responsiveness, thereby regulating chemical reaction pathways. It should be noted that chemical reactions are not solely governed by quantum confinement effects; they also involve the combined regulation of factors such as reactant concentration and configuration, distribution orientation, local effective pressure, and thermal conductivity arising from spatial confinement. This section focuses exclusively on the impact of quantum confinement effects on chemical reactions. From a quantum mechanical perspective, when an electron’s wave function is confined to a small space, its nonlinear displacement in an electromagnetic field is markedly enhanced. The confined space encompasses not only the overall dimensions of the material but also defects and impurities within the bulk phase or at the surface/interface. Applications of quantum confinement effects in chemistry include low-dimensional catalytic materials, self-assembly reactions driven by resonance resulting from the superposition of cluster wave functions and indirect tunneling effects, catalysts designed through defect engineering, and single-atom catalysts formed by the dispersion of transition-metal atoms on the surface of support materials［148–154］.
3.2 Surface Plasmon Polaritons
To facilitate understanding, we first clarify the relevant concepts. Plasma, also referred to as the fourth state of matter beyond solid, liquid, and gas, is an electrically neutral ionized system that comprises cations, anions, neutral particles, and electrons. It exhibits high electrical conductivity and responds strongly to electromagnetic fields. Although conventional plasmas are predominantly in a gaseous state, their collective wave characteristics have led to their inclusion within the scope of condensed matter physics research. With the advancement of related studies, free-electron systems in solids or liquids driven by electromagnetic fields can also be regarded as plasmas. The high-energy state of plasma endows it with exceptional chemical reactivity, enabling interactions with solid surfaces, liquids, or microorganisms. Plasmas find extensive applications in surface etching, surface modification, and defect engineering. Plasmons, or plasmon excitations, represent the quantized form of plasma resonance and possess long-range electron–electron correlations［155-156］. Research on plasmons has primarily focused on metal nanoparticles, metal surfaces, and metal–semiconductor interfaces. A plasmon can be understood as the quantization of periodic oscillations in electron density surrounding cations within a metal. When plasmons couple with photons, plasmon polaritons are formed. Light below the plasmon frequency is reflected at the material’s surface, whereas light above this frequency propagates through the material due to insufficient electronic response. At resonance, surface plasmon polaritons emerge at metal–air or metal–semiconductor interfaces, with electromagnetic waves traveling along the interface at near-infrared or visible-light frequencies. The coherent oscillations of electrons occurring at the metal surface are termed surface plasmons, while the electromagnetic waves propagating into the air or semiconductor are referred to as polaritons［157］. Surface plasmon polaritons are confined to the interface, giving rise to intense light–matter interactions, and have traditionally been employed in optical sensing, microscopy, and communications. Recently, localized surface plasmon resonances have garnered significant attention for their applications in chemical reactions, as they induce pronounced charge separation at the metal surface and enhance near-field amplitudes, thereby exerting a substantial influence on reaction kinetics. As shown in Figure 16a, under specific wavelength illumination, localized surface plasmon resonance effects generate localized electric fields on the surface of metal nanoparticles. The principal effects arising from nanoparticle surface plasmon resonances are threefold: (1) electromagnetic field enhancement; (2) carrier dynamics; and (3) thermal effects. These effects occur over timescales ranging sequentially from femtoseconds to nanoseconds. When metal nanoparticles are brought into close proximity with semiconductor surfaces, enhanced electric fields can be observed at their interface, leading to multifactorial coupling effects, as depicted in Figure 16b. The geometric configuration of metal clusters significantly influences both the incident light wavelength required for resonance and the spatial distribution of localized surface plasmons. As illustrated in the theoretical calculations presented in Figure 16c, the electric field tends to concentrate at the sharp tips of the nanoparticles and decays rapidly along straight edges［158］. Furthermore, controlling the interparticle spacing markedly affects the degree of electric field enhancement and the peak resonance wavelength. In addition, localized surface plasmon resonances can provide multiple catalytic effects, including intramolecular charge transfer, hot-carrier transport, and thermal driving forces［159］. Figure 16d depicts the impact of Ag20 nanoparticle–induced localized surface plasmon resonance on the C—O bond cleavage in CO2 molecules. As shown in Figure 16e, although the Ag20 nanoparticle provides an enhanced electric field intensity along the CO2 axis, the field strength diminishes substantially in the vicinity of the CO2 molecule and is insufficient to directly induce C—O bond rupture. By monitoring the temporal evolution of charge distribution within the CO2 molecule, as illustrated in Figure 16f, it is evident that at 16 fs the CO2 molecule received 0.63 electrons from the Ag20 nanoparticle, indicating that the photocatalytic reduction of CO2 by this nanoparticle is driven by charge transfer mediated by localized plasmon resonance. This exemplifies the typical application of surface plasmons—as a concept rooted in condensed matter physics—in chemical catalysis.
3.3 Topological insulators
According to the band structure, materials are generally classified into insulators, metals, semiconductors, and semi-metals (Semi-metal and half metal). Since there is no clear boundary between the bands of insulators and semiconductors, they are collectively referred to as insulators. A topological insulator is a class of material systems that exhibit insulating behavior in the bulk phase but possess conductive edge states; its surface states differ significantly from those of ordinary insulators (Figure 17)［160］. Three-dimensional topological insulators have conductive surface states, whereas two-dimensional topological insulators exhibit one-dimensional linear conductive edge states. Compared with conventional insulators, the band structure of a topological insulator displays a “twisted and knotted” feature. It cannot be transformed into an ordinary insulator through continuous local perturbations unless the topological knots formed by the intertwined electronic wave functions are untied［161］. Topological insulators occupy a distinct position in the phase diagram, separate from ordinary insulators, connected by a conducting phase, and cannot be described by Landau’s theory of symmetry breaking［162］. Currently, research on topological insulators is primarily concentrated in the field of physics, with potential applications in spintronic devices, dissipationless transistors, magneto-optoelectronic devices, and so on. Their application in chemical reactions remains limited, with most studies focusing on the transition metals contained within their constituents rather than on the unique properties of topological insulators themselves. Recently, Japanese researchers reported that bismuth selenide (Bi2Se3) nanoparticles can catalyze the oxidative carbonylation of amines with carbon monoxide and oxygen to synthesize urea derivatives. Under conditions of 20 ℃, the carbonylation of butylamine was completed, achieving a yield of up to 99% within 4 hours［163］, as shown in Figure 18a. To verify the role of topological properties, the researchers tested the catalytic efficiency of different catalysts. Figure 18b indicates that bulk Bi2Se3exhibited a very high turnover frequency (TOF) for the carbonylation of butylamine, yet the rate of product formation was relatively low. This was attributed to the small specific surface area of the bulk catalyst, which resulted in a limited number of exposed catalytic sites. In contrast, when Bi2Se3nanoparticles were used as the catalyst, the TOF remained stable while the rate of product formation increased significantly, highlighting the critical importance of the specific surface area. Subsequently, after replacing the Bi element in the catalyst with other elements, the researchers observed a marked decrease in TOF, indicating that neither Bi nor Se alone plays a dominant role in the catalytic reaction. Taken together, these results suggest that the synergistic interaction between Bi and Se—or more precisely, the surface states of Bi2Se3—is the primary factor driving this catalytic process. Theoretical calculations further demonstrate that the surface states of topological insulators can convert triplet oxygen molecules into singlet states, thereby promoting oxygen activation and facilitating the formation of urea derivatives, thus confirming the catalytic contribution of topological surface states. This study indicates that the topological insulating properties exhibited by Bi2Se3can catalyze similar oxidative carbonylation reactions under relatively mild conditions, enabling the synthesis of various urea derivatives. Looking ahead, the conductive surface states of topological insulators, which facilitate charge carrier transport and separation in semiconductors, are expected to find broader applications in chemical reactions. Moreover, topological materials can be extended to include topological semimetals—such as Weyl semimetals, Dirac semimetals, nodal-line semimetals, and multidegenerate nodal-point semimetals—whose chemical application potential remains to be explored［164］.
4 Conclusion and Outlook
This paper briefly introduces the development history of condensed matter physics and the evolution of its name, while also recognizing the main differences between condensed matter physics and condensed matter chemistry in their respective research domains. By examining the structural dynamic evolution in typical solid–gas, solid–liquid, and solid–solid interfacial reactions, the core concept of condensed matter structural chemistry is highlighted: under reaction conditions, the structure of a material system continuously undergoes dynamic evolution, necessitating that chemical research fully account for the influence of relevant factors. External conditions—such as mechanical force, electric fields, magnetic fields, and light—are synergistically involved in inducing changes in material structure, thereby driving chemical reaction processes and accompanying continuous dynamic structural transformations. These structural evolutions further affect the microenvironment near reaction sites—for example, local electric fields, pH values, dielectric shielding, and spatial confinement—thereby regulating reaction kinetics and selectivity.
However, constrained by current computational capabilities, the application of quantum mechanical theory in complex chemical reaction systems remains inadequate, making it difficult to fully reproduce real reaction processes. Due to the complexity and diversity of chemical reaction systems, there is still no unified theoretical framework capable of describing the vast majority of chemical reactions. As research in condensed matter physics deepens, novel material phenomena continue to emerge, providing new perspectives and application potentials for the field of chemistry. For example, physical concepts such as quantum confinement effects, surface plasmon resonances, and topological insulators have demonstrated significant value in catalysis, photochemistry, and materials synthesis. These advances have laid a solid theoretical and practical foundation for the vigorous development of condensed matter chemistry and condensed matter structural chemistry.
As an important experimental characterization method, ultrafast time-resolved in-situ techniques will experience significant advancements in the foreseeable future, including but not limited to: ultrafast transient absorption spectroscopy, in-situ super-resolution microscopy, spatiotemporal omics technologies, and ultrashort laser-pulse scanning tunneling microscopy. These in-situ characterization techniques can provide real-time observational data at the femtosecond and sub-nanometer scales under authentic reaction conditions, thereby furnishing first-hand experimental observations and relevant critical evidence for condensed-phase chemical research. With the rapid progress and iterative development of artificial intelligence technologies, researchers are expected to leverage AI- or machine learning-assisted approaches to investigate more complex condensed-phase chemical processes, conduct more refined dynamic structural simulations, and deliver theoretical research outcomes in condensed-phase chemistry that are increasingly aligned with reality. The integration of advanced in-situ characterization methods with artificial intelligence and other cutting-edge technologies will serve as a powerful driving force for advancing chemical research, effectively ushering chemical science into the realm of condensed phases. This convergence will lay the necessary scientific groundwork for achieving greater breakthroughs in elucidating chemical reaction mechanisms, designing catalysts, implementing multi-field coupling control, and conducting efficient, energy-saving chemical synthesis. Interdisciplinary integration, particularly the synergistic collaboration between condensed-matter physics and chemistry, will further facilitate the discovery and application of novel chemical reaction pathways, offering innovative solutions for energy, environmental, and materials science sectors.
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