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High-entropy materials, for both complexity in structure and superiority in performance, have been widely confirmed to be one possible kind of advanced electrocatalyst. Significant efforts have been dedicated to modeling the atomic-level details of high-entropy catalysts to improve the viability for bottom-up design of advanced electrocatalysts. In this review, first, we survey developments in various modeling methods that are based on density functional theory. We review progress in density functional theory simulations for emulating different high-entropy electrocatalysts. Then, we review the advancements in simulations of high-entropy materials for electrocatalytic applications. Finally, we present prospects in this field. Abbreviations: HEMs: high-entropy materials; CCMs: compositionally complex materials; DFT: density functional theory; LDA: local density approximation; GGA: generalized gradient approximation; VASP: Vienna Ab initio simulation package; ECP: effective core potential; PAW: projector-augmented wave potential; VCA: virtual crystal approximation; CPA: coherent potential approximation; SQS: special quasi-random structures; SSOS: small set of ordered structures; SLAE: similar local atomic environment; HEAs: high-entropy alloys; FCC: face-centered cubic; BCC: body-centered cubic; HCP: hexagonal close-packed; ORR: oxygen reduction reaction; OER: oxide evolution reaction; HER: hydrogen evolution reaction; RDS: rate-limiting step; AEM: adsorbate evolution mechanism; LOM: lattice oxygen oxidation mechanism; HEOs: high-entropy oxides; OVs: oxygen vacancies; PDOS: projected densities of states; ADR: ammonia decomposition reaction; NRR: nitrogen reduction reaction; CO2RR: CO2 reduction reaction; TMDC: transition metal dichalcogenide; TM: transition metal; AOR: alcohol oxidation reaction; GOR: glycerol oxidation reaction; UOR: urea oxidation reaction; HEI: high-entropy intermetallic. This paper reviews recent developments in the field of atomistic simulations of high-entropy electrocatalysts, one of emerging state-of-the-art catalytic materials. [ABSTRACT FROM AUTHOR]

Single atom alloy (SAA) catalysts, consisting of oxide supported dilute alloy nanoparticles (NPs), have become increasingly popular due to their unique chemical reactivity and ability to selectively facilitate catalytic reactions. While SAA catalysts are typically synthesized with a uniform alloy composition, it is well known that the surface composition can vary from that in the bulk due to environmental conditions. Herein we demonstrate how environmental conditions can impact the structure of Pt in supported silver-platinum (AgPt) dilute alloy NPs. We employ ab initio thermodynamic models parameterized by density functional theory calculations to explore favorable structures under inert conditions and in the presence of adsorbates such as carbon monoxide (CO). These calculations show that in the absence of strongly interacting adsorbates, Pt is favored to reside in the Ag bulk, while under CO rich environments, Pt is stabilized at the surface in a variety of configurations. We experimentally verify these calculations by colloidally synthesizing AgPt NPs supported on alumina and characterizing Pt structures using electron microscopy paired with in situ infrared spectroscopy and X-ray absorption spectroscopy. Detailed characterization shows evidence that isolated Pt sites can be stabilized at the surface in the presence of CO and, depending on environmental conditions, that some fraction of surface Pt atoms are coordinated to sub-surface Pt. Density of states calculations show that structures where surface Pt is coordinated to subsurface Pt have markedly different electronic structures and therefore suggests such changes in Pt coordination environment can influence catalytic processes. [ABSTRACT FROM AUTHOR]

The adsorption simulation of acetic acid, methanol, and triacetin has been carried out on the ZnO and V-doped ZnO (V-ZnO) through computational study. The DFT/B3LYP method was applied using the Def2-TZVP basis set. The results show that the acetic acid adsorption on the ZnO surface was the most favorable among the others. The insertion of V atom into the ZnO surface causes the adsorption energy more negative. The NBO charge analysis was carried out to analyze the interaction between adsorbate molecules and the adsorbate. It was found that the charge transfer between acetic acid and the ZnO or V-ZnO surface has the highest value indicating that acetic acid adsorption plays an important role in the esterification reaction. [ABSTRACT FROM AUTHOR]

Single-atom catalysts (SACs) have been applied in many fields due to their superior catalytic performance. Because of the unique properties of the single-atom-site, using the single atoms as catalysts to synthesize SACs is promising. In this work, we have successfully achieved Co1 SAC using Pt1 atoms as catalysts. More importantly, this synthesis strategy can be extended to achieve Fe and Ni SACs as well. X-ray absorption spectroscopy (XAS) results demonstrate that the achieved Fe, Co, and Ni SACs are in a M1-pyrrolic N4 (M= Fe, Co, and Ni) structure. Density functional theory (DFT) studies show that the Co(Cp)2 dissociation is enhanced by Pt1 atoms, thus leading to the formation of Co1 atoms instead of nanoparticles. These SACs are also evaluated under hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), and the nature of active sites under HER are unveiled by the operando XAS studies. These new findings extend the application fields of SACs to catalytic fabrication methodology, which is promising for the rational design of advanced SACs. Synthesizing single-atom catalysts through a general method presents a great challenge. Here the authors report that Fe, Co and Ni single-atom catalysts can be obtained using pre-located isolated Pt atoms as the catalyst and identify the role of Pt single atoms in the synthesis process. [ABSTRACT FROM AUTHOR]

The mechanistic analysis in heterogeneous catalysis is based on listing all elementary steps and evaluating explicitly their energies. To this end, computational models based on Density Functional Theory have become a standard to estimate the information needed in mechanistic studies. Typically, either the minimum energy paths or those with the smaller span are summarized in reaction profiles. Such simplifications gather a lot of information, although further dimensionality reduction is required to obtain the most relevant descriptors of catalytic activity and generate the so‐called volcano plots. The selection of descriptors has been traditionally based on simple intermediates, such as central atoms in small molecules (as C in CH4), which have good thermodynamic correlations to other fragments containing them. Yet, in emerging processes (recent studies), the number of intermediates involved increase, configurational effects and lateral interactions become significant, and complex materials with low symmetry are employed, thus the simple rules encapsulated in linear scaling relationships lose their predictive power due to error accumulation. At the same time, large datasets generated for the intermediates call for statistical analysis and thus these techniques are being leveraged to chemical systems, particularly to reduce their dimensionality. This article is categorized under:Structure and Mechanism > Reaction Mechanisms and CatalysisStructure and Mechanism > Computational Materials ScienceElectronic Structure Theory > Ab Initio Electronic Structure Methods [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) was rapidly developed and achieved a great success in the last decades. As the advancement of general concepts in heterogeneous catalysis, theoretical study of chemical reactions based on DFT calculations has become more and more feasible, which provides a guideline for the rational design of novel catalysts toward higher reaction activity and specific selectivity. Here, we review an innovate scheme, namely reaction phase diagram (RPD), which can offer not only an in‐depth understanding of reaction mechanisms, but also the prediction of catalytic activity and selectivity trend over a collection of catalysts. The RPD analysis was successfully applied to understand the activity variation of CO2 electroreduction to CO and formic acid, as well as thermochemical hydrogenation and dehydrogenation. Meanwhile, the RPD analysis also exhibits a success of studying the product selectivity in syngas conversion to methane, ethanol, and methanol with complicated reaction pathways. At the end, we review a successful case of catalyst rational design with a target of NO selective electroreduction to ammonia. The foundation of RPD analysis is based on the scaling relation of adsorption energies and the correlation between kinetic barriers and reaction energies at elementary steps. Therefore, microkinetic modeling is complementary to the RPD analysis. A few of limitations and the prospect of the development regarding the RPD analysis are addressed in this review. This article is categorized under:Structure and Mechanism > Reaction Mechanisms and Catalysis [ABSTRACT FROM AUTHOR]

Electrified interfaces play a prime role in energy technologies, from batteries and capacitors to heterogeneous electrocatalysis. The atomistic understanding and modeling of these interfaces is challenging due to the structural complexity and the presence of the electrochemical potential. Including the potential explicitly in the quantum mechanical simulations is equivalent to simulating systems with a surface charge. For realistic relationships between the potential and the surface charge (i.e., the capacity), the solvent and counter charge need to be considered. The solvent and electrolyte description are limited by the computational power: either molecules or ions are included explicitly or implicit solvent and electrolyte descriptions are adopted. The first option is limited by the phase‐space sampling that is at least 10 times too small to reach convergence, while the second is missing a realistic structuring of the interface. Both approaches suffer from a lack of validation against directly comparable experimental data. Furthermore, the limitations of density functional theory in terms of accuracy are critical for these metal/liquid interfaces. Nevertheless, the atomistic insight in electrocatalytic interfaces allows insights with unprecedented details. The joint theoretical and experimental efforts to design non‐noble hydrogen evolution catalysts are discussed as an example for the success of theory to spur and accelerate experimental discoveries. This article is categorized under:Structure and Mechanism > Reaction Mechanisms and CatalysisElectronic Structure Theory > Density Functional Theory [ABSTRACT FROM AUTHOR]

Condensed phase reactions have recently attracted increased interest, but principles for efficiently screening and designing catalyst materials through computations are lacking. In this study, we examine the applicability of energy correlations between adsorbed surface species, which have been instrumental in accelerating the computational design of catalyst materials in gas‐phase contexts, in various representations of a condensed phase reaction environment. We perform detailed density functional theory calculations of the adsorption of atomic and molecular species in the presence of various representations of solvent species. Our results show that the well‐known scaling in the gas phase context is preserved, with scaling slopes unaffected by the adsorbate‐liquid interactions. Moreover, these results hold when changing surface structure, solvent identity, and even in highly disordered environments. We envision the establishment of an energy scaling framework for condensed phase reactions to accelerate catalyst discovery and design in those contexts. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of CO2 into value-added chemicals should reduce the consumption of fossil fuels and counteract global warming caused by CO2 generation. Nonetheless, CO2 is rather stable and chemically inert, calling for effective electrocatalysts to avoid problems such as sluggish kinetics, low reaction efficiency and poor product selectivity during CO2 conversion. Recently, single-atom catalysts have shown maximum atom utilization and unique catalytic performance during electrochemical reactions. Catalysts used have been developed from poorly controlled nanoparticles or nanoclusters to isolated atomic structures. Herein, we review the preparation, characterization, anchoring strategies and electrochemical applications of single-atom catalysts. Concerning methods of preparation, the use of organometallic ligands shows high potential for synthesis and industrial applications. Both characterization and calculations using the density functional theory allow to assess the atomic distribution, the coordination environment and the catalytic mechanism. To improve synthesis, we present four anchoring strategies: defect engineering, atom coordination, spatial confinement and sacrifice template. Applications in electrochemical reduction of CO2 to liquid and gaseous products reveal Faraday efficiency higher than 90%, excellent activity, selectivity, stability and kinetic properties. [ABSTRACT FROM AUTHOR]

A theoretical study of oxygen adsorption on gold and gold-silver surfaces by means of density functional theory (DFT) calculations with an atomistic thermodynamic model is performed. The (111) and (211) facets of gold and gold-silver alloy surfaces are considered, and their stabilization is discussed upon adsorption of oxygen depending on O and Ag coverage. The details of how the DFT-based atomistic thermodynamic model can apply to the transition metal surface are also presented in this work. [ABSTRACT FROM AUTHOR]

Rational design of catalysts has long been an important and challenging goal in heterogeneous catalysis. To achieve this target, density functional theory ( DFT) calculations and micro-kinetics are two of the cornerstones. The DFT calculations make it possible to obtain microscopic properties of catalytic systems by computational simulations, and the micro-kinetic modeling of surface reactions provides a tool to link quantum-chemical data with macroscopic behaviors of the systems. In this review, we focus on the basic concepts and latest theoretical progresses of strategies for the catalysts design, including Brønsted−Evans−Polanyi relation, the volcano curve, and the activity window. Among the progresses, the theory of chemical potential kinetics in heterogeneous catalysis and its implications on catalysts design, which was developed by our group, are described in detail with extensive derivations. Furthermore, the applications of this method on screening low-cost counter electrodes for dye-sensitized solar cells are presented with experimental evidences. WIREs Comput Mol Sci 2017, 7:e1321. doi: 10.1002/wcms.1321 For further resources related to this article, please visit the . [ABSTRACT FROM AUTHOR]

The adsorption of water on bimetallic PtRu/Pt(111) surface alloys has been studied based on periodic density functional theory calculations including dispersion corrections. The Ru atoms of the PtRu surface alloy interact more strongly with water than Pt atoms, as far as both single water molecules and ice-like hexagonal structures are concerned. Within the surface alloy layer, the lateral ligand effect reducing the local reactivity of the surface atoms with increasing Ru content is more dominant than the opposing geometric effect due to the tensile strain. The structural preference for the Ru atoms also prevails at room temperature, as ab initio molecular dynamics simulations show. [ABSTRACT FROM AUTHOR]

It has recently been shown that the dynamic behavior of surface‐supported nanocluster catalysts in realistic reaction conditions defies conventional models used in catalysis. This opens new doors in catalysis by giving more leverage in catalyst design, but also requires a major revision of the understanding of how dynamic heterogeneous catalytic interfaces operate, as well as of the computational approaches of catalyst modeling, and experimental methods of catalyst characterization. Major aspects of the new paradigm include the collective action of many catalyst states that form a statistical ensemble in reaction conditions, the catalytic activity and selectivity being driven by rare and metastable catalyst states, reaction thermodynamics and kinetics being controlled by different states of the catalyst, broken scaling relationships, non‐Arrhenius behaviors, and catalyst dynamic restructuring being an essential part of the reaction mechanism. For computation, this complexity means the departure from the standard density functional theory calculations of reaction mechanisms on a single catalyst structure. For experiment, it calls for the development of operando characterization tools with the per‐site resolution and the ability to find the minority sites that govern the catalytic activity. For catalyst design, the goal becomes the creation of the catalyst state (geometric and electronic) that might not be present in the as‐prepared catalyst, but would develop in the reaction conditions and would have the desired activity then. While cluster catalysts are the most dramatic in their dynamic fluxionality, other amorphous interfaces also exhibit some of it, and thus are also subject to similar paradigm revision. This article is categorized under:Structure and Mechanism > Reaction Mechanisms and Catalysis [ABSTRACT FROM AUTHOR]