Recent Advances and Perspectives of Electrochemical CO2 Reduction Toward C2+ Products on Cu-Based Catalysts

Renewable-electricity-powered electrochemical CO2 reduction reactions (CO2RR) to highly value-added multi-carbon (C2+) fuels or chemicals have been widely recognized as a promising approach for achieving carbon recycling and thus bringing about sustainable environmental and economic benefits. Cu-based catalysts have been demonstrated as the only candidate metal CO2RR electrocatalysts that catalyze the C-C coupling. Unfortunately, huge challenges still exist in the highly selective CO2RR to C2+ products due to the higher activation barrier of C-C coupling and complex multi-electron reaction. Key fundamental issues regarding both active species and product formation pathways have not been elucidated by now, but recent developments of advanced strategies and characterization tools allow one to comprehensively understand the Cu-based CO2RR mechanism. Herein, we review recent advance and perspective of Cu-based CO2RR catalysts, especially in terms of active phases and product formation pathways. Then, strategies in catalysts design for CO2RR toward C2+ products are also presented. Importantly, we systematically summarized the advanced tools for investigating the CO2RR mechanism, including in situ/operando spectroscopy techniques, isotope labeling, and theoretical calculations, aiming at unifying the knowledge of active species and product formation pathways. Finally, future challenges and constructive perspectives are discussed, facilitating the accelerated advancement of CO2RR mechanism research.