Identifying active sites of boron, nitrogen co-doped carbon materials for the oxygen reduction reaction to hydrogen peroxide

The electrochemical synthesis of hydrogen peroxide (H₂O₂) from two-electron oxygen reduction reaction (2e^- ORR) is a promising alternative for producing chemicals on demand, but its widespread application is still hampered by the low efficiency. Here, we successfully prepared a boron and nitrogen co-doped porous carbon (B/N[sbnd]C) aerogel with a tunable B, N co-doped configuration by the gelation of PVA-graphene, borax and PANI, followed by pyrolysis. Due to a hierarchical porous structure and optimized B, N co-doping, B/N[sbnd]C aerogel showed an excellent electrocatalytic performance for H₂O₂ production in alkaline solution with a high H₂O₂ selectivity (94.16%) at positive applied potential (0.6 V vs. RHE), superior than most of the other reported electrocatalysts. Density functional theory (DFT) calculations reveal that the hexagonal boron nitride (hBN) coupled with neighboring pyridinic-N species act as the active sites to lower free energy barrier for formation of HOO* intermediate, thus facilitating H₂O₂ production. Practically, B 2p electron plays an important role for the adsorption of HOO* intermediates. B and N co-doping into carbon materials provides an effective and facile method to reasonably construct carbon-based catalysts for electroreduction of O₂ to H₂O₂.