Insight into Structural Evolution, Active Sites, and Stability of Heterogeneous Electrocatalysts.

Studying structure-activity correlations of electrocatalysts is essential for improving the conversion of electrical to chemical energy. Recently, increasing evidence obtained by operando characterization techniques reveal that the structural evolution of catalysts caused by the interplay with electric fields, electrolytes and reactants/intermediates brings about the formation of real active sites. Hence, it is time to summarize structural evolution related research advances and envisage future developments. In this Minireview, we first introduce the fundamental concepts associated with structural evolution (e.g., catalysts, active sites/centers and stability/lifetime) and their relevance. Then, the multiple triggers of structural evolution and advanced operando characterizations are discussed. Significantly, a brief overview of structural evolution and its reversibility in heterogeneous electrocatalysis is provided, especially for the representative electrocatalytic oxygen evolution reaction (OER) and CO2 reduction reaction (CO2 RR) processes. Lastly, key challenges and opportunities in this exciting field are highlighted.