The continued massive consumption of fossil fuels in modern societies has led to a range of environmental issues, including excessive CO2 emissions. In this regard, electrochemical CO2 reduction can convert intermittent electricity into chemical fuels and other value-added products, which holds the potential to close the carbon cycle. Among the various catalysts, metals are the most extensively studied heterogeneous CO2RR electrocatalysts and can be classified into three categories based on the main products. Containing Bi, Sn, In, Pb, and Cd (formate), Au, Ag, and Zn (CO), and Cu (multicarbon products).
The development of Cu-based catalysts has garnered significant attention due to the higher energy density and added value of the multicarbon products. However, the reaction network is extremely complex, involving multi-step electron/proton transfer reactions and interactions among various intermediates. Moreover, the structure of Cu catalysts undergoes dynamic reconstruction under operating conditions, which significantly affects their catalytic performance. The reconstruction process is influenced by many factors (electrolyte, electrolysis mode, catalyst structure and microenvironment, etc.). These factors constrain stability and selectivity, complicating the development of structure-activity relationships. Recent advancements in in-situ/operando characterization techniques enable real-time monitoring of the dynamic evolution. Combined with density functional theory (DFT) calculations, in-situ/operando studies can help give a picture of how catalytic sites reconstruct during electrolysis and how they influence catalytic performance.
Recently, a research team led by Prof. Chen Chen from Tsinghua University (China) presents a general overview of the recent advances regarding the dynamic surfaces of Cu-based catalysts. This review begins with the discussion of the mechanism of C2+ product (ethylene, ethanol, acetate and propanol, etc.) generation. The structural factors promoting the generation of C2+ products (crystal facets, low coordination sites and oxidation states) are reviewed, and the dynamic evolution of these structural factors is discussed. Subsequently, from the perspective of dynamic surfaces, the effects of cation effect and pulsed electrochemical method on the catalytic performance are discussed. Finally, it looks ahead to the further exploration of reconstruction mechanisms and the application of robotic AI chemists to study CO2RR. The results were published in Chinese Journal of Catalysis (https://doi.org/10.1016/S1872-2067(24)60185-3).
