Arc plasma‐deposited Co single‐atom catalysts supported on an aligned carbon nanofiber for hydrogen peroxide electrosynthesis and an electro‐Fenton process

Atomically dispersed single‐atom catalysts (SACs) on carbon supports show great promise for H2O2 electrosynthesis, but conventional wet chemistry methods using particulate carbon blacks in powder form have limited their potential as two‐electron (2e−) oxygen reduction reaction (ORR) catalysts. Here, we demonstrate high‐performance Co SACs supported on a free‐standing aligned carbon nanofiber (CNF) using electrospinning and arc plasma deposition (APD). Based on the surface oxidation treatment of aligned CNF and precise control of the deposition amount in a dry‐based APD process, we successfully form densely populated Co SACs on aligned CNF. Through experimental analyses and density functional theory calculations, we reveal that Co SAC has a Co–N2–O2 moiety with one epoxy group, leading to excellent 2e− ORR activity. Furthermore, the aligned CNF significantly improves mass transfer in flow cells compared to randomly oriented CNF, showing an overpotential reduction of 30 mV and a 1.3‐fold improvement (84.5%) in Faradaic efficiency, and finally achieves an outstanding production rate of 15.75 mol gcat−1 h−1 at 300 mA cm−2. The high‐performance Co SAC supported on well‐aligned CNF is also applied in an electro‐Fenton process, demonstrating rapid removal of methylene blue and bisphenol F due to its exceptional 2e− ORR activity. Co single atoms on free‐standing aligned carbon nanofiber supports (Co@EO‐ACNF15) prepared by electrospinning and arc plasma deposition processes are used for a highly active two‐electron (2e−) oxygen reduction reaction (ORR) catalyst. The Co@EO‐ACNF15 catalyst achieves outstanding mass activity, selectivity, and H2O2 production rate. Furthermore, we demonstrate wastewater treatment via the electro‐Fenton reaction based on the excellent 2e− ORR activity.