Emerging Electrocatalysts for Water Oxidation under Near-Neutral CO2 Reduction Conditions

Electrocatalytic CO2 reduction reaction (CO2RR), which produces valuable fuels and chemicals under near-neutral conditions, offers a renewable approach to alleviate the global energy crisis as well as the increasing concerns on climate change. However, to implement this strategy, one of the major challenges, the sluggish kinetics of the paired oxygen evolution reaction (OER) at anode, needs to be surmounted. It is therefore highly desirable to explore high-performance and cost-effective OER electrocatalysts suitable for CO2RR conditions, which is very different from those widely investigated under acidic or alkaline conditions. In this review, the ongoing development of OER electrocatalysts under near pH-neutral CO2-saturated (bi)carbonate solutions are highlighted and the future opportunities are discussed. It is started with a brief introduction on OER paired with CO2RR, the relevant theoretical tools such as density functional theory (DFT) and particularly machine learning (ML), and the operando characterization techniques. Then, there are some detailed discussions of recent progress on the rational design of OER electrocatalysts under CO2RR conditions ranging from noble-metal oxides to nonprecious metal phosphides, carbonates, (hydro)oxides, and so on. Finally, a perspective for developing OER electrocatalysts integrated with CO2 electroreduction is proposed.