Computational Study of the Curvature-Promoted Anchoring of Transition Metals for Water Splitting

Recent Advances on Two-Dimensional Nanomaterials Supported Single-Atom for Hydrogen Evolution Electrocatalysts

Water electrolysis has been recognized as a promising technology that can convert renewable energy into hydrogen for storage and utilization. The superior activity and low cost of catalysis are key factors in promoting the industrialization of water electrolysis. Single-atom catalysts (SACs) have attracted attention due to their ultra-high atomic utilization, clear structure, and highest hydrogen evolution reaction (HER) performance. In addition, the performance and stability of single-atom (SA) substrates are crucial, and various two-dimensional (2D) nanomaterial supports have become promising foundations for SA due to their unique exposed surfaces, diverse elemental compositions, and flexible electronic structures, to drive single atoms to reach performance limits. The SA supported by 2D nanomaterials exhibits various electronic interactions and synergistic effects, all of which need to be comprehensively summarized. This article aims to organize and discuss the progress of 2D nanomaterial single-atom supports in enhancing HER, including common and widely used synthesis methods, advanced characterization techniques, different types of 2D supports, and the correlation between structural hydrogen evolution performance. Finally, the latest understanding of 2D nanomaterial supports was proposed.

Curved Structure Regulated Single Metal Sites for Advanced Electrocatalytic Reactions

Curved surface with defined local electronic structures and regulated surface microenvironments is significant for advanced catalytic engineering. Since single-atom catalysts are highly efficient and active, they have attracted much attention in recent years. The curvature carrier has a significant effect on the electronic structure regulation of single-atom sites, which effectively promote the catalytic efficiency. Here, the effect of the curvature structure with exposed metal atoms for catalysis is comprehensively summarized. First, the substrates with curvature features are reviewed. Second, the applications of single-atom catalysts containing curvature in a variety of different electrocatalytic reactions are discussed in depth. The impact of curvature effects in catalytic reactions is further analyzed. Finally, prospects and suggestions for their application and future development are presented. This review paves the way for the construction of high curvature-containing surface carriers, which is of great significance for single-atom catalysts development.

Which Is Better for Hydrogen Evolution on Metal@MoS2 Heterostructures from a Theoretical Perspective: Single Atom or Monolayer?

Single atom (SA)- and monolayer (ML)-supported catalysts are two main technical routines to increase electrochemical catalytic performance and reduce cost. To date, it is still a debate which one is better for catalysis in experiments as both routines face a puzzling problem of searching for balance between stability and catalytic activity. Here, hydrogen evolution on two-dimensional 2H-MoS₂ with SA- and ML-adsorbed metal atoms (23 kinds in total) is taken as an example to solve this question by first-principles calculations. The thermodynamic stability during synthesis, in vacuum, and in electrochemical reaction conditions is determined to access the stability of MoS₂ loaded with single (M_S@MoS₂) and monolayer metal atoms (M_M@MoS₂). The realistic catalytic surfaces determined by surface Pourbaix diagrams, the free energy changes of hydrogen atoms at different coverages, and the exchange current densities are applied to determine hydrogen evolution reaction (HER) activity. The results show that all M_M@MoS₂ are much more stable than the corresponding M_S@MoS₂ as the metal-metal interaction in MLs could make the former structures more stable. In general, M_M@MoS₂ show higher hydrogen evolution activities than those of M_S@MoS₂. In detail, the exchange current densities of MoS₂ loaded by Pd ML and Au ML are 6.208, and 1.109 mA/cm^-2, respectively, which are comparable to Pt(111). Combining with small binding energies, the Pd and Au MLs are the most promising catalysts for hydrogen evolution. The purpose of this work is to highlight the advantages and disadvantages of SA- and ML-supported surfaces as HER catalysts and provide a fundamental standard for studying them.