Inert anode in a high-temperature molten salt system and oxygen generation by moon regolith electrolysis

In 2020, China proposed to reach the peak of CO₂ emissions before 2030 and achieve carbon neutrality by 2060, which is the so-called “carbon peak and carbon neutrality” strategy. Due to strategic requirements, the metallurgical industry has the responsibility of reducing its CO₂ emission as it is one of the major CO₂ emitters. Therefore, it is imperative to develop low-carbon metallurgical technology. High-temperature molten salt electrochemical metallurgy uses electrons as the energy carrier and reaction driving force, having the advantages of cleanliness and high efficiency. It is the main extraction technology for aluminum, rare earth elements, alkali metal, and alkaline earth metals. Currently, carbon anodes are commonly used in molten salt electrochemical metallurgy, and CO₂ product is an important carbon emission source. If an inert oxygen evolution anode is used in a high-temperature molten salt system, then low-carbon emissions can be achieved in the molten salt electrolysis process. Therefore, the development of inert anodes suitable for molten salt electrolysis systems is very important, which has recently become a worldwide research hotspot. This article first reviewed the research progress of inert anodes in various high-temperature molten salt systems, including aluminum electrolytic fluoride salts, CaCl₂ molten salts, carbonates, and molten oxides. Meanwhile, the recent development and the utilization of the moon have received widespread attention. In the future construction of lunar bases, oxygen will be the basic prerequisite for human survival. Solar-driven in-situ oxygen production with molten salt electrochemistry from the moon regolith will be an important method in the future to support the oxygen demand for human survival on the moon. Hence, inert oxygen evolution anodes are essential. Therefore, this article also briefly summarized oxygen production technology by moon regolith electrolysis based on inert anodes.