Anchored Ni nanocrystals boosting BiVO4 photoanode for highly efficient water oxidation via in-situ generation of Ni@NiOOH co-catalyst

In this work, Ni nanocrystals as oxygen evolution reaction co-catalysts for water splitting are anchored on a porous bismuth vanadate (BiVO4) photoanode through facile dip-coating and annealing procedures. The resulting Ni/BiVO4 hybrid photoanode achieves an outstanding photocurrent density of 4.41 mA/cm2 at 1.23 V vs RHE, 3.2 times higher than pristine BiVO4 photoanode. A favorable PEC durability can be observed for Ni/BiVO4 hybrid photoanode with only a 4.7 % decay of photocurrent density within 10 h. Furthermore, results of Raman spectrum, X-ray photoelectron spectroscopy (XPS) etc., confirm that an ultrathin amorphous NiOOH layer is in-situ generated on Ni nanocrystals after an activation process, forming a robust Ni@NiOOH co-catalysts. The unique core–shell structure enables the Ni@NiOOH co-catalyst to couple the high electrical conductivity and high oxygen evolution activity, contributing to the enhanced photoelectrochemical performance. Importantly, this study paves a facile strategy to accomplish the desirable co-catalyst/semiconductor coupling towards efficient solar fuels production.