Abstract
Electricity-driven proton exchange membrane water electrolyzers are a promising technology to produce dihydrogen gas (H-2). However, this technology is limited by the anodic oxygen evolution reaction that controls the overall operation efficiency, since only few electrocatalysts are efficient under the strongly acidic and oxidative conditions. Accordingly, there is a need for electrocatalysts with high activity, high stability, and low cost for the reaction of acidic oxygen evolution. Here, we review electrocatalysis using the acidic oxygen evolution reaction. We discuss two mechanisms of the oxygen evolution reaction: the adsorbate evolution mechanism and the lattice oxygen mechanism. We then summarize strategies to improve the performance of electrocatalysts by active site engineering, electron distribution optimization, interaction modulation, vacancy engineering, and lattice strain regulation. Challenges include the understanding of mechanisms of the oxygen evolution reaction, the operation durability at industrial currents, the flow reactor design of proton exchange membrane water electrolyzers, the alternative reactions, the development of nonprecious metal-based electrocatalysts, and large-scale synthetic approaches of electrocatalysts. Finally, precautions for electrochemical tests are proposed.