Modification of BiVO4/WO3 composite photoelectrodes with Al2O3via chemical vapor deposition for highly efficient oxidative H2O2 production from H2O

Abstract

The modification of a BiVO₄/WO₃ photoelectrode with Al₂O₃ by a chemical vapor deposition (CVD) method significantly improved the faradaic efficiency for H₂O₂ production (FE(H₂O₂)) in the photoelectrochemical oxidation of H₂O. The faradaic efficiency after passing 0.9 C (after photoirradiation for 15 min using simulated solar light) was 80% using a 2.0 M KHCO₃ aqueous solution as an electrolyte. The initial FE(H₂O₂) (<0.02 C) was almost 100% on the Al₂O₃/BiVO₄/WO₃ photoelectrode. The thin Al₂O₃ layer prevents the oxidative decomposition of the produced H₂O₂ into O₂. The applied bias photon to current efficiency (ABPE) was 2.57% based on H₂O₂ and O₂ production on the photoanode and H₂ production on a Pt cathode. Solar light driven simultaneous H₂O₂ production at the anode for H₂O oxidation and the cathode for O₂ reduction was also achieved by combining a noble-metal-free biomass-derived carbon cathode without applying any external bias.