New paradigm of in situ characterization for next-generation CO2 electroreduction towards multi-carbon products over Cu-based catalysts

The electrochemical reduction of CO2 (CO2RR) into valuable chemicals and fuels is a promising approach for sustainable energy storage and compromising greenhouse gas emissions, among which the formation of higher-valued multi-carbon products (C2+) is desired. However, selective CO2RR to C2+ usually suffers from a low reaction rate and low selectivity for the complex and long pathways. More seriously, the catalytic system involving catalyst, interface and microenvironment changes dynamically at realistic working conditions, which regrettably causes misleading results regarding the promoted factor and reaction mechanism of CO2RR. To this regard, it is necessary to develop the advanced in situ techniques to track the dynamic evolution of the catalytic system under operating conditions. Here, we discuss the necessary factors and key challenges in producing C2+ products, including current state-of-the-art copper-based catalyst, as well as the dynamic evolution of the catalyst structure, oxidation state and composition. Then, we present the strategies using advanced in situ and operando characterizations to monitor the deep triggers of dynamic evolution and deeply understand the reaction mechanism. Finally, we highlight how the cross-coupled model and data-driven flow enable the new paradigm of in situ characterization with higher accuracy and efficiency.