Research advances in utilization of CO<sub>2</sub> resources for oxygen production in Space Station and Mars environments

The establishment of stable cycling of CO2 and O2 is essential for Environmental Control and Life Support Systems (ECLSS) in extraterrestrial environments, particularly for long-duration missions aboard Space Stations and future Martian bases. The development of CO2-to-O2 technologies demonstrating superior oxygen recovery rates, enhanced CO2 conversion efficiency, and optimized energy efficiency is critical for achieving closed-loop material regeneration. This review systematically examines technological status in extraterrestrial CO2-to-O2 conversion, categorizing emerging approaches into two frameworks: “two-step oxygen generation” and “one-step oxygen generation”. Two-step oxygen generation includes thermal catalytic CO2 hydrogenation reduction and electrolysis of water for O2 production, which are primarily utilized in Space Station; one-step oxygen generation encompasses electrocatalytic reduction of CO2 and plasma catalytic CO2 conversion, which are predominantly employed in Martian environments. Through comparative analysis of underlying principles and operational characteristics, we identify three critical challenges impeding technological maturation: (1) The deactivation of catalytic materials, the formation of carbon deposits, and the inadequacy of catalytic mechanisms; (2) the description of the transformation process is unclear, making it challenging to regulate the conversion. Additionally, suppressing side reactions proves to be difficult; and (3) the degree of recycling for a single technological substance is relatively low. The development of effective, efficient, stable, and reliable CO2-to-O2 technology will provide a solid foundation for reducing launch costs and ensuring sustainable human habitation in extraterrestrial environments.