Electrochemical CO2 reduction to C2+ products using Cu-based electrocatalysts: A review

With the disruptive carbon cycle being blamed for global warming, the plausible electrocatalytic CO2 reduction reaction (CO2RR) to form valuable C2+ hydrocarbons and feedstock is becoming a hot topic. Cu-based electrocatalysts have been proven to be excellent CO2RR alternatives for high energy value-added products in this regard. However, the selectivity of CO2RR to form C2+ products via Cu-based catalysts suffers from a high overpotential, slow reaction kinetics, and low selectivity. This review attempts to discuss various cutting-edge strategies for understanding catalytic design such as Cu-based catalyst surface engineering, tuning Cu bandgap via alloying, nanocatalysis, and the effect of the electrolyte and pH on catalyst morphology. The most recent advances in in situ spectroscopy and computational techniques are summarized to fully comprehend reaction mechanisms, structural transformation/degradation mechanisms, and crystal facet loss with subsequent effects on catalyst activity. Furthermore, approaches for tuning Cu interactions are discussed from four key perspectives: single-atom catalysts, interfacial engineering, metal-organic frameworks, and polymer-incorporated materials, which provide new insights into the selectivity of C2+ products. Finally, major challenges are outlined, and potential prospects for the rational design of catalysts for robust CO2RR are proposed. The integration of catalytic design with mechanistic understanding is a step forward in the promising advancement of CO2RR technology for industrial applications.