Atomically Dispersed Co/Mo Sites Anchored on Mesoporous Carbon Hollow Spheres for Highly Selective Oxygen Reduction to Hydrogen Peroxide in Acidic Media

Abstract Two‐electron oxygen reduction reaction (2e − ORR) in acidic media is a promising route for the decentralized and on‐site hydrogen peroxide (H 2 O 2 ) generation. Nevertheless, strong interaction between active sites and * OOH intermediates usually induces the O─O bond cleavage to convert 2e − pathway into the sluggish 4e − ORR. Therefore, it is highly necessary to optimize the electronic structure of 2e − ORR electrocatalysts for the regulation of adsorption energy. Herein, we propose the utilization of atomically dispersed Co/Mo sites anchored on mesoporous carbon hollow spheres (Co/Mo‐MCHS) via a template‐engaged strategy for highly selective ORR to H 2 O 2 in acid. Benefitting from the electron‐donating effect of Mo atoms, an enriched electron density around the Co center for Co/Mo‐MCHS is observed, resulting in optimal adsorption of the key * OOH intermediates to approach the apex of 2e − ORR volcano plot. Moreover, the introduction of Mo species simultaneously suppresses the electroreduction of as‐obtained H 2 O 2 on Co sites. As a consequence, Co/Mo‐MCHS delivers a high H 2 O 2 selectivity of 90–95% in acid. The flow cell based on the Co/Mo‐MCHS catalyst achieves a remarkable H 2 O 2 yield of 2102 mg for 150 h. Moreover, this strategy can be extended to other early transition metal elements with similar electronic modifier effects.