Decoration of AgOx hole collector to boost photocatalytic water oxidation activity of BiVO4 photoanode

Abstract

BiVO4 is a promising light harvester for the construction of photoanode for solar-driven water splitting, but it suffers from low charge mobility and slow oxygen evolution reaction kinetics. Herein, we report on a novel strategy using AgOx (e.g. Ag2O and AgO) nanoparticles as hole collectors to boost the BiVO4 photoanode to its best photocatalytic performance. AgOx helps to boost the charge transfer efficiency at the BiVO4/electrolyte interface up to 93%, being much higher than 40% achieved for a bare BiVO4 photoanode. AgOx also contributes to improving the photostability of BiVO4 by offering an efficient quenching of the photogenerated holes, which are harmful to the BiVO4, e.g. causing an oxidative dissolution of V. In a pH 7 phosphate buffer electrolyte and under 1 sun illumination, the best BiVO4/AgOx photoanode generates a photocatalytic current density of 4.65 mA/cm2 at 1.23 V vs. reversible hydrogen electrode. It represents a 2.3-fold improvement of activity in comparison to a bare BiVO4 without AgOx decoration. The current BiVO4/AgOx can be placed among the top-tier photoanodes for solar water splitting made of BiVO4 light harvester.