Recent Progress in Energy-Saving Electrocatalytic Hydrogen Production via Regulating Anodic Oxidation Reaction

Hydrogen energy with the advantages of high calorific value, renewable nature, and zero carbon emissions is considered an ideal candidate for clean energy in the future. The electrochemical decomposition of water, powered by renewable and clean energy sources, presents a sustainable and environmentally friendly approach to hydrogen production. However, the traditional electrochemical overall water-splitting reaction (OWSR) is limited by the anodic oxygen evolution reaction (OER) with sluggish kinetics and high energy consumption. Besides, the generation of reactive oxygen species at high oxidation potentials can lead to equipment degradation and increase maintenance costs. To address these challenges, a series of innovative hydrogen production systems have been developed. These systems involve coupling the cathodic hydrogen evolution reaction (HER) with thermodynamically favorable anodic oxidation reactions that have lower oxidation potentials, or adjusting the pH gradient of the electrolytes. In this review, we aim to provide an overview of the advancements in electrochemical hydrogen production strategies with low energy consumption, including (1) traditional electrochemical overall water splitting reaction (OWSR, HER-OER); (2) The small molecule sacrificial agent oxidation reaction (SAOR) and (3) the electrochemical oxidation synthesis reaction (EOSR) coupling with the HER (HER-SAOR, HER-EOSR), respectively; (4) Regulating the pH gradient of the cathodic and anodic electrolytes. The operating principle, advantages, and the latest progress of these hydrogen production systems are analyzed in detail. Furthermore, we also provide a perspective on the potential challenges and future directions to foster further advancements in electrocatalytic green sustainable hydrogen production.