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.