Non-noble metal catalysts for preventing chlorine evolution reaction in electrolytic seawater splitting

Compared with freshwater resources, seawater is cheaper and more abundant. However, the abundance of chloride ions in seawater affects the oxygen evolution reaction at the anode, and thus it is necessary to develop efficient oxygen-producing anode catalysts for direct electrolytic seawater splitting. Among the numerous anode catalysts, non-noble metal materials have prime industrial application prospects due to their easy availability and low price. Thus, to grasp the current research status of non-noble metal electrocatalysts used in the electrolysis of direct seawater splitting anodes, herein we classify these catalyst materials and summarize them based on three aspects. i.e., structural analysis, mechanism research, and application conditions. Firstly, we analyze the mechanism of the chlorine evolution reaction and oxygen evolution reaction in seawater and the competitive relationship between them. Subsequently, based on the functional types of non-noble metal anode catalysts, they are divided into high-selectivity catalysts and chloride ion barrier layer catalysts. Also, we present certain experimental methods to evaluate the high-selectivity efficiency of anode catalysts for reference. Finally, the existing problems associated with anodic electrocatalysts for seawater cracking are elaborated and their future development directions are prospected.