Operando surface reconstruction steers the electrochemical CO2 reduction behaviors.

Electrochemical CO2 reduction is an important route to realize carbon neutrality while converting CO2 into value-added chemicals. However, its practical application is hindered by the poorly controlled surface reconstruction of electrocatalysts occurring at the catalytic interface, which leads to difficulties in the identification of authentic active sites and modulation of reconstruction behaviors. In this review, we emphasize the importance of uncovering the dynamic structural evolutions of working electrocatalysts through advanced theoretical simulation methods, with a particular focus on Cu- and Sn-based catalysts, whose structures are known to strongly influence product selectivity. First, we summarize the surface reconstruction mechanisms of electrocatalysts and the corresponding effects on surface microenvironments, mesoscopic morphology, and reduction products. Then, we highlight recent studies on deciphering the surface coverage species of electrocatalysts during electrocatalysis and simulating the dynamic surface reconstruction and the interfacial C-C coupling process using advanced theoretical methods. Finally, we provide an outlook on unravelling and harnessing surface reconstruction, including the development of in situ characterization techniques, machine learning-assisted multiscale simulations, and surface reconstruction engineering. We expect that this review will accelerate the study of surface reconstruction occurring in the CO2RR and other electrocatalytic systems for the rational design of next-generation catalysts.