Surface reconstruction-derived heterostructures for electrochemical water splitting

Electrocatalytic water splitting for green hydrogen generation is of great significance for renewable energy conversion and storage. The development of efficient electrocatalysts to reduce the energy barriers of the two half-reactions of hydrogen evolution (HER) and oxygen evolution (OER) is the key to realize the high-efficiency industrialization of electrochemical water splitting. With the continuous investment of research efforts, diverse transition metal-based catalysts have flourished, and their dynamic structural reconstruction during electrocatalytic OER and HER has also been pushed into a research upsurge. Since most transition metal compounds are thermodynamically unstable under electrochemical OER or HER conditions, they tend to undergo dynamic structural evolution to reach a relatively stable state, whereby the in situ reconstructed surface as the real reactivity species induces the changes in catalytic activity, which brings challenges to understanding the real catalytic mechanism and also motivates the development of surface reconstruction as a novel strategy to design superior heterostructure catalysts. At present, how to rationally utilize surface reconstruction to achieve breakthroughs in catalytic performance has become a critical focus area. This review summarizes the recent progress of surface reconstruction-derived heterostructures for electrocatalytic OER and HER, highlighting the fundamental understanding of surface reconstruction behaviors, the correlation between the intrinsic structure and dynamic reconstruction process of pristine catalysts, and some possible catalytic mechanisms that responsible for the enhanced catalytic activity. Moreover, several instructive design strategies of catalysts for modulating structural reconstruction to obtain optimized activity including heteroatom doping/substitution, anion/cation induction, structural defects, and heterostructure construction, are then introduced. Finally, we put forward the challenges and outlooks for surface reconstruction engineering, providing new insights and directions for future research development.