Electrocatalytic seawater splitting from direct electrolysis to hybrid electrolysis: Challenges and opportunities

Abstract

The electrochemical splitting of seawater for hydrogen production presents a promising avenue toward sustainable energy goals; nevertheless, its realization confronts formidable challenges, including adversarial chlorine-related processes, sluggish kinetics, limited catalyst durability, and the interference of impurities and precipitates. This comprehensive review commences with an overview of recent noteworthy advancements and rational strategies in catalyst design specifically tailored for seawater electrolysis. Addressing the unique challenges at the anode and cathode during direct seawater electrolysis, we delve into pioneering methodologies for fabricating efficacious anodic and cathodic catalysts. These approaches encompass catalyst design principles, selective active sites, and the implementation of Cl⁻ blocking layers. Furthermore, a detailed exploration of substitutional anodic oxidation reactions involving various small molecules, coupled with cathodic hydrogen evolution, is provided as a means to achieve hybrid seawater electrolysis. This dual-functional approach ensures not only secure and energy-efficient seawater splitting but also paves the way for the simultaneous generation of value-added chemicals and the amelioration of environmental contaminants. Additionally, advanced reactor assembly concepts tailored for seawater electrolysis are introduced to enhance overall system efficiency. In conclusion, we offer distinctive insights poised to guide future research endeavors in the domain of seawater electrolysis systems.