Photoelectrochemical Hydrogen Peroxide Production from Water on a WO3/BiVO4 Photoanode and from O2 on an Au Cathode Without External Bias

The photoelectrochemical production and degradation properties of hydrogen peroxide (H2O2) were investigated on a WO3/BiVO4 photoanode in an aqueous electrolyte of hydrogen carbonate (HCO3−). High concentrations of HCO3− species rather than CO32− species inhibited the oxidative degradation of H2O2 on the WO3/BiVO4 photoanode, resulting in effective oxidative H2O2 generation and accumulation from water (H2O). Moreover, the Au cathode facilitated two-electron reduction of oxygen (O2), resulting in reductive H2O2 production with high current efficiency. Combining the WO3/BiVO4 photoanode with a HCO3− electrolyte and an Au cathode also produced a clean and promising design for a photoelectrode system specializing in H2O2 production (ηanode(H2O2)≈50 %, ηcathode(H2O2)≈90 %) even without applied voltage between the photoanode and cathode under simulated solar light through a two-photon process; this achieved effective H2O2 production when using an Au-supported porous BiVO4 photocatalyst sheet.