Selective and Efficient Gd-Doped BiVO₄ Photoanode\nfor Two-Electron Water Oxidation to H₂O₂

Abstract

Photoelectrochemical\noxidation of water presents a pathway for\nsustainable production of hydrogen peroxide (H₂O₂). Two-electron water oxidation toward H₂O₂, however, competes with the popular four-electron process to form\noxygen and one-electron water oxidation to form OH radical. To date,\nbismuth vanadate (BiVO₄) has been shown to exhibit promising\nselectivity toward H₂O₂, especially under illumination,\nbut it suffers from high overpotential and notoriously poor stability.\nHerein, using density functional theory calculations, we predict that\ndoping BiVO₄ with optimal concentrations of gadolinium\n(Gd) not only enhances its activity for H₂O₂ production but also improves its stability. Experimentally, we demonstrate\nthat intermediate amounts of Gd doping (6–12%) reduce the onset\npotential of BiVO₄ for H₂O₂ production\nby ∼110 mV while achieving a Faradaic efficiency of ∼99.5%\nunder illumination and prolonging the catalytic lifetime by more than\na factor of 20 at 2.0 V vs RHE under illumination.