Enhanced H2O2 production by selective electrochemical reduction of O2 on fluorine-doped hierarchically porous carbon

Abstract

Electrochemical synthesis of hydrogen peroxide (H2O2) via two-electron pathway of oxygen reduction reaction is a promising alternative to the current anthraquinone process. The H2O2 production from O2 is a competing reaction with four-electron O2 reduction to H2O, and the selectivity is related to the adsorption energy of the OOH intermediate on electrocatalysts surface. Generally, the properties for binding of OOH intermediate on catalysts can be controlled by changing its electronic structure. Herein, the electronic structure of porous carbon materials was tuned by doping different types and contents of fluorine species. The yield of H2O2 generation depended on the F content and the best catalytic activity toward H2O2 electrosynthesis was obtained with F content of 3.41 at.%. The resultant F-doped porous carbon (FPC) catalysts exhibited good H2O2 selectivity of 97.5–83.0% and the H2O2 production rate could reach 112.6–792.6 mmol h−1 g−1 over the potential range of 0.2 V to −0.3 vs. RHE (pH 1). The density functional theory (DFT) calculations and experiments revealed that the incorporation of CF2, 3 into carbon plane promotes the activation of O2 molecule and facilitates desorption of OOH intermediate, which was crucial to H2O2 synthesis.