Structural evolution of Cu2O nanocube electrocatalysts for the CO2 reduction reaction

Cu-based electrocatalysts are unique to generate C2+ chemicals and fuels during the electrochemical reduction of CO2. Although the activity and selectivity of Cu-based electrocatalysts (e.g. Cu and its alloy nanostructures and oxide-derived Cu) have shown great potential for practical electrochemical production, the stability of current Cu-based electrocatalysts largely hinders their practical applications. Herein, we select Cu2O nanocubes as a model catalyst to investigate the origin of instability and structural evolution of Cu2O nanocube electrocatalysts, which are tracked by detailed electron microscopic analysis corroborated by theoretical calculations. We found the structural instability origins from the O loss induced by H attacking under the electrochemical environment and followed by a series of structural and morphological transitions, i.e., from a dense nanocube to nanocube with rough surface, then to a hollow-shell structure, and finally transformed to aggregates of smaller nanoparticles with mixed Cu and Cu oxide phases. The genesis of Cu2O nanocubes revealed here provides insights into rational design electrocatalysts towards CO2 reduction reaction with long-term stability, and can be extrapolated to other Cu-based nanostructured electrocatalysts.