Carboxylated Hexagonal Boron Nitride/Graphene Configuration for Electrosynthesis of High-Concentration Neutral Hydrogen Peroxide.

The electrosynthesis of hydrogen peroxide (H2O2) via two-electron (2e-) oxygen (O2) reduction reaction (ORR) has great potential to replace the traditional energy-intensive anthraquinone process, but the design of low-cost and highly active and selective catalysts is greatly challenging for the long-term H2O2 production under industrial relevant current density, especially under neutral electrolytes. To address this issue, this work constructed a carboxylated hexagonal boron nitride/graphene (h-BN/G) heterojunction on the commercial activated carbon through the coupling of B, N co-doping with surface oxygen groups functionalization. The champion catalyst exhibited a high 2e- ORR selectivity (>95%), production rate (up to 13.4 mol g-1 h-1), and Faradaic efficiency (FE, >95%). The long-term H2O2 production under the high current density of 100 mA cm-2 caused the cumulative concentration as high as 2.1 wt.%. The combination of in-situ Raman spectra and theoretical calculation indicated that the carboxylated h-BN/G configuration promotes the adsorption of O2 and the stabilization of the key intermediates (OOH* and HOOH*), allowing a low energy barrier for the rate-determining step of HOOH* release from the active site, and thus improving the 2e- ORR performance. The fast dye degradation by using this electrochemical synthesized H2O2 further illustrated the promising practical application.