Atomic-Level Co/Mesoporous Carbon Nanofibers for Efficient Electrochemical H2O2 Production

Carbon-based nanomaterials have garnered significant attention for their use in oxygen reduction reactions (ORRs) due to their distinctive electronic properties, adjustable structural features, and robust long-term operational stability. Recently, developing efficient electrochemical catalysts to produce hydrogen peroxide (H2O2) has become a crucial pursuit in the energy field. However, it is a challenge to precisely control the composition of the catalyst for H2O2 through a two-electron ORR. In this study, we demonstrated a strategy for fabricating highly selective two-electron ORR catalysts based on atomic-level cobalt (Co)-grafted porous carbon nanofibers. A series of Co-based catalysts with mesoporous structures were successfully fabricated by using cobalt nitrate and carbon quantum dots through electrostatic spinning, heat treatment processes under an ammonia atmosphere, and acid etching. With these processes, we are able to produce atomic-level Co coordinated with N2-O2 grown on mesoporous carbon nanofibers, as confirmed by synchrotron X-ray absorption spectroscopy and scanning transmission electron microscopy. Fine-tuning the surrounding atomic configuration of the Co atom enables a two-electron ORR for H2O2 production. For instance, at a potential of 0.65 V, the selectivity of the catalyst for H2O2 was as high as 96%, and the as-prepared catalyst exhibited a kinetic current density of 2.57 mA cm-2 with a number of electron transfers of similar to 2. This current investigation provides a simple and convenient method for preparing atomic-level Co grafted on a mesoporous nanofiber-based catalyst for efficient electrochemical H2O2 production.