Mo or W doping into the surface of BiVO4 film photoanodes through a photoelectrochemical treating approach for efficient solar water oxidation

Abstract

In theory, suitable metal ions doping into the surface of BiVO4 photoanodes could improve its water oxidation performance effectively. But the common homogeneous reaction strategy is not well applicable for the preparation of BiVO4 film photoanodes with metal ions surface doping. Herein, a photoelectrochemical treating approach was reported to prepare BiVO4 films with W or Mo surface doping in saturated tungstate and molybdate-containing electrolyte, respectively. The doping of W or Mo into the surface of BiVO4 film was attributed to the following reactions. Firstly, the photocorrosion of BiVO4 film photoelectrodes resulted in the dissolution of VO43+ from BiVO4 lattice under AM 1.5 G illumination. Then, the WO42+ or MoO42+ in the saturated electrolyte entered and occupied the dissolved sites of VO43+ on BiVO4 surface through ions exchange reaction. Due to the lower radiative recombination of carrier as well as higher electrocatalytic water oxidation activity, the resultant W or Mo doped BiVO4 films as photoanodes showed better solar water oxidation activity, kinetics and stability, although their light harvesting property and morphological feature were close to the pristine BiVO4 film photoanode. The present work provides a new and effective approach for the achievement of metal ions doping into the surface of BiVO4 photoanodes, which could inspire the preparation of similar photoanode materials.