Strategies for overcoming seawater adverse effects on cathodic hydrogen evolution reaction electrocatalysts

Hydrogen is the ideal energy to resolve the depletion and shortage of fossil fuel. Seawater electrolysis to hydrogen has been considered the strategic direction for large-scale hydrogen production in the future. The cathodic hydrogen evolution reaction (HER) electrocatalyst is vital to the seawater electrolysis efficiency. However, the complex seawater causes the detrimental side reactions of corrosion, precipitation and deposition reactions to the HER electrocatalysts. To overcome these adverse effects, four efficient strategies of stable structure, polyanion passivating layer, protective coating, and unique nanostructure have been developed. These strategies could effectively repel Cl−, strengthen corrosion resistance, and prevent precipitates/deposits adhesion. Therefore, the stability and activity retention of the HER electrocatalysts for seawater electrolysis have been significantly improved. However, the problems of low stability, unclear electrocatalyst structure and reaction mechanism, inactive and unstable coating, as well as inferior performances to industrial requirement hinder the development of seawater electrocatalysts on HER. Then, the outlooks have been put forward for future research. Exploration of super-stable electrocatalysts, verifying reconstructed structures and reaction mechanism, utilization of ion exchange membranes, optimization outer environment of electrocatalysts would boost the development of seawater electrocatalysts and large-scale hydrogen production, benefitting mankind to achieve the "dual carbon goals".