Surface engineering of Cu catalysts for electrochemical reduction of CO₂ to value-added multi-carbon products

Copper (Cu) is the most efficient metal that can electrochemically convert CO₂ to various chemical feedstocks at reasonable efficiency. The activity and selectivity toward the CO₂ reduction reaction (CO₂RR) largely depend on the surface sensitivity and electrokinetics of Cu catalysts. Surface engineering is achievable through tuning the structure and through crystal orientation. The Cu-surface modulation and tunings, e.g., controlled morphology, oxygen vacancies, and alloys on supports or substrates, propose different reaction tracks and intermediates, whereas common routes are ∗CO dimerization, C–C, and C₁–C₂ coupling for the formation of C₂ and C₃ products. In this review, recent progress on the surface engineering of Cu-based catalysts is primarily recaptured and explained. The fragmentation, coalescence, and aggregation of Cu nanoparticles cause stability issues of Cu catalysts during the CO₂RR, which has also been discussed. Finally, we summarize critical strategies and approaches to surface engineering of Cu-based catalysts for the efficient CO₂RR.