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

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.