Phase regulation of WO3 for highly selective oxygen reduction to hydrogen peroxide

Abstract

Hydrogen peroxide (H2O2), as one of the most important chemicals, is widely applied in many industries. Electrocatalytic oxygen reduction provides a safe and on-site method for H2O2 synthesis. The research of transition metal oxides (TMOs) for H2O2 synthesis is mainly focused on the modification of transition metal elements and graphene. Few studies directly control pure TMOs without changing supporting materials or introducing other elements. Here, we demonstrate for the first time a phase regulation strategy to develop highly selective and stable tungsten trioxide catalysts for H2O2 generation through 2e− oxygen reduction reaction (2e− ORR). DFT calculations show that the kinetic energy barrier (0.08 eV) of the 2e− ORR pathway on the cubic tungsten trioxide (c-WO3) surface is much lower than that of the 4e− ORR pathway (0.76 eV). As a result, a selectivity of 90 % and H2O2 production rate of 179 mmol gcat−1h−1 are achieved at 0.1 V vs RHE under alkaline conditions, outperforming all catalysts previously reported under the same conditions. Moreover, after continuous testing for more than 24 h at a constant potential of 0.1 V vs RHE, the H2O2 generation rate has not been diminished, indicating an excellent stability of c-WO3 in practical applications.