Dynamic evolution of copper-based catalysts during CO2 electroreduction

The CO₂ electroreduction reaction (CO₂RR) is a promising approach of using renewable electricity to synthesize fuels and value-added chemicals. At present, Cu is generally considered to be the major monometallic catalyst capable of producing multicarbon products (C₂₊) with high current densities from the CO₂RR, but it still suffers from the low activity and high overpotential. The challenge of sluggish CO₂RR kinetics can be overcome by developing efficient Cu-based catalysts, which undergo the dynamic evolution during the reaction process. The dynamic evolution of the Cu-based catalysts taking place under working conditions makes it difficult to study the structure-activity correlation and reaction mechanism present during CO₂RR. Recently, a number of important works have observed and revealed the dynamic evolution process of Cu-based catalysts by operando characterization techniques. This aspect, however, remains less summarized and prospected in the CO₂RR literature. In this Review, we summarize the dynamic evolution of Cu-based catalysts during the CO₂RR from aspects of structure, composition and oxidation state. We highlight the correlations between evolution behaviors and catalytic properties. Then, we discuss the dynamic deactivation process of Cu-based catalysts during CO₂RR, including metal impurities contamination and carbon accumulation. In particular, we introduce recent advancements in in situ characterization techniques those are employed to probe the dynamic evolution under operating conditions. We end the Review by outlining the challenges and offering personal perspectives on the future development opportunities in this field.