Cutting-edge methods for amplifying the oxygen evolution reaction during seawater electrolysis: a brief synopsis

Abstract

Electrochemical water splitting has been considered a clean and continual way for hydrogen (H₂) production. Direct seawater electrolysis is a potentially attractive technology due to the ample access to seawater and scarce freshwater resources in some regions. However, the presence of impurities (e.g., Cl⁻, Mg²⁺) and the resulting corrosion and side reactions, such as the chloride oxidation reaction (ClOR), makes seawater electrocatalysis more challenging than that of fresh or alkaline water due to competition with the oxygen evolution reaction (OER) at the anode. Consequently, much effort has been devoted to developing approaches to enhance OER performance and suppress the ClOR. In this minireview, we summarize three general strategies for enhancing OER activity and selectivity in seawater electrolysis based on three different concepts: (1) the sole development of robust and high-performance OER catalysts in pure seawater electrolytes, (2) the introduction of additives to seawater electrolytes (e.g., alkalis and/or salts without chloride) to enhance the potential equilibrium gap between the ClOR and OER in combination with regular highly active OER catalysts, and (3) a combination of approaches (1) and (2). Finally, the current challenges and potential opportunities for green H₂ production from seawater electrolysis are briefly presented.

Keywords: Electrochemical seawater splitting; Alkaline seawater electrolysis; Oxygen evolution reaction; Hydrogen production; Electrocatalysts.