Surface Modulation Inducing Bismuth-Rich Surface Composition in BiVO4 for Efficient Photoelectrochemical Water Splitting

Surface engineering affects the photoelectrochemical properties of multinary oxide photoelectrodes. Here, we report a simple alkaline solution treatment of the (010) faceted bismuth vanadate (BiVO 4 ) photoanode to increase the surface ratio of bismuth to vanadium, thus improving the performance of photoelectrochemical water oxidation. This study demonstrates that the preferential vanadium dissolution occurs in an alkaline solution, resulting in a bismuth-rich surface on the outer region of the pristine BiVO 4 to afford the formation of homojunction within BiVO 4 . The homojunction promotes the charge separation efficiency of the treated BiVO 4 photoanode to reach an almost ∼100% enhancement at 1.23 V RHE under simulated sunlight. Upon further loading NiFeO x cocatalyst, the maximum applied-bias photon-to-current conversion efficiency (ABPE) of treated BiVO 4 photoanode also shows a further 100% enhancement in 0.1 M KPi electrolyte. This study sheds light on the critical role of surface termination/composition on the photoelectrochemical properties of the BiVO 4 photoanode. This essential surface property can be modulated through a simple strategy to improve its charge transport for efficient water oxidation.