Photoelectrochemical water splitting has attracted increasing attention recently in the perspective of clean and sustainable energy economy. Herein, we reported the synthesis of NiO functionalized Mo doped BiVO4 (denoted as NiO/Mo:BiVO4) nanobelts and their enhanced photoelectrochemical activity for efficient water oxidation. The prepared Ni0/ Mo:BiVO4 p-n junction structure showed much higher water splitting activity than the pristine BiVO4 and Mo:BiVO4. Such obvious enhancement are due to the increased donor density by doping with Mo and fast separation of the photoexcited electron hole pairs by the novel p n junction composite structure. Under light irradiation, photoexcited holes in the conduction band (CB) of Mo:BiVO4 will conveniently transfer to the p-type NiO with the effect of the inner electric field. Meanwhile, the holes would oxidize the water into oxygen and the electrons transfer to the counter electrode (Pt electrode) to produce hydrogen. This novel p n junction structure could open up new opportunities to develop highperformance photoanode for water splitting. Copyright