Recent Progress in Cathode Material Design for CO₂ Electrolysis: From Room Temperature to Elevated Temperatures

Abstract

Conspectus Rapid economic growth and societal development have led to an ever-increasing demand for energy; the excessive exploration and use of fossil fuels have caused an alarming level of carbon dioxide (CO2) emission into the atmosphere, adversely impacting the environment and quality of life in human society. CO2 electrolysis (CO2RR) offers the opportunity to store renewable energy (such as wind, solar, or tidal energy) in the form of chemicals and fuels while reducing CO2 emissions. Through the CO2RR process, a variety of chemicals and fuels can be obtained using different electrocatalysts. Based on the different operating temperature and reaction conditions, CO2 electrolysis can be categorized into low-temperature and high-temperature CO2RR. To date, great effort has been devoted to designing the electrocatalysts that can improve the electrocatalytic performance for CO2RR, including catalytic activity, selectivity, and stability. For low-temperature CO2RR, different approaches have been utilized to optimize the catalyst structure and properties, thereby enhancing the electrocatalytic performance. Given the different working mechanism of high-temperature CO2RR operating in the solid oxide electrolysis cells (SOECs), the cathode materials not only need to meet the requirements of the low temperature but also need to possess high ionic and electronic conductivity, robust coking resistance, and superior compatibility with the electrolytes. In pursuit of this objective, considerable effort is directed toward designing more efficient and effective cathode electrodes for high-temperature CO2RR. Beyond traditional metal and metal oxide materials, perovskite-based materials are emerging as promising candidates due to their unique structure and favorable performance in CO2RR at elevated temperatures. In this Account, we present recent research progress on the design of cathode materials in CO2 electrolysis. We first discuss low-temperature CO2RR electrocatalyst design using different engineering strategies, including structural engineering, defect engineering, phase engineering, doping engineering, interface engineering, and microenvironment engineering. Combined with some representative work from our group and other researchers, the advantages of these diverse strategies are further elucidated, providing a more in-depth understanding of electrocatalyst design. Then, we summarize the cathode materials for high-temperature CO2RR utilization based on the material types such as metal/metal oxides and perovskite-based materials. Further discussion of different approaches, such as infiltration, doping, and in situ exsolution is summarized, aims to improving the electrocatalytic performance of perovskite-based materials for high-temperature CO2RR. Finally, we present current challenges and future prospects of CO2 electrolysis in both the design of cathode materials and the reaction system, with the goal of achieving more profitable applications.