Recent progress on copper catalysts with different surface states for CO2 electroreduction

The electrochemical carbon dioxide reduction reaction (eCO₂RR), which converts CO₂ into various hydrocarbons or alcohols, has been extensively researched because it promises a sustainable energy economy. However, only copper (Cu) can currently achieve stable and efficient hydrocarbon conversion in the eCO₂RR. Therefore, understanding the catalytic mechanisms and summarizing the research progress on synthesis strategies of Cu catalysts are essential for the eCO₂RR. This paper reviews Cu catalysts with different surface states of Cu catalysts: oxide-derived Cu, Cu nanoparticles, Cu single atoms, and Cu nanoclusters. It then reviews the development and progress of different Cu-catalyst preparation methods in recent years, focusing on the activity and selectivity of materials. Besides revealing the tendencies of catalytic selection and deep reactive mechanisms of Cu catalysts with four different surface states, this review can guide the subsequent construction of catalysts and provides an understanding of catalytic mechanisms.