Enzyme-inspired molecular electrocatalysts for the oxygen reduction reaction

Enzymes with high efficiency and selectivity in biological catalysis have fuelled great interest in being utilized in catalysis apart from living organisms. Owing to the similarity between some enzymatic oxygen reduction reaction (ORR) and electrocatalytic four-electron (4e−) ORR processes in bonding with O2, electron transfer between catalysts and substrates/intermediates, and reduction processes from O2 to H2O, enzyme-inspired ORR electrocatalysts have been widely studied. Notably, artificially synthesized molecular electrocatalysts inspired by enzymes can inhibit the limitations of low yield, limited sources, thermal instability, and poor reusability of the direct use of enzymes yet also exhibit high activity and robust stability over specific reactions. This minireview focuses on enzyme-inspired molecular electrocatalysts, especially cytochrome c oxidases and multicopper oxidases, for efficient electrocatalytic oxygen reduction. Furthermore, we outline the challenges and outlook needed to guide the design and application of enzyme-inspired molecular electrocatalysts for the ORR.