Significance of an anion effect in the selective oxidation of Ce3+ to Ce4+ over a porous WO3 photoanode

Abstract Herein we report the oxidation of Ce 3+ to Ce 4+ using a porous WO 3 photoanode and a Pt cathode with excellent Faradaic efficiency (FE (Ce 4+ )) of up to 98% under solar simulated light in an aqueous electrolyte solution containing a high concentration of SO 4 2− anions. The competing side oxidative reactions such as S 2 O 8 2− and O 2 production were found to be suppressed in the presence of Ce 3+ . The Ce 4+ yield (YI (Ce 4+ )) from Ce 3+ reached up to 95%. Also, a noble-metal-free biomass-derived inexpensive electrode was found to be an efficient replacement of the Pt cathode.