Recent advances in energy chemistry of precious-metal-free catalysts for oxygen electrocatalysis

The oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are coupled with various sustainable energy systems and are significant for the future energy scenario. Both of them suffer from sluggish kinetics, which calls for cost-effective and high-performance electrocatalysts to promote. The oxygen electrolysis of OER and ORR is heterogeneous reaction, which involves reactant and electron transfer, and a serial of complicate surface reactions. Both intrinsic catalyst activity and extrinsic physicochemical characters play a vital role in overall electrocatalytic reactivity. Herein, recent advances in rational design and effective construction of precious-metal-free materials are reviewed for OER and ORR, respectively, in the respects of electronic structure regulation, nanostructure tailor, and freestanding electrode fabrication. The reaction mechanism of OER and ORR are also updated. This review provides emerging energy chemistry concepts and materials chemistry strategies of electrocatalysts for OER and ORR, which is also enlightening for other energy conversion devices with targeted optimization.