BiVO4 optimized to nano-worm morphology for enhanced activity towards photoelectrochemical water splitting

Abstract

The article reports the preparation of unique worm-like BiVO₄ nanoparticles through hydrothermal treatment of scheelite tetragonal BiVO₄ obtained by a simple precipitation method. The as-obtained nano-worms were ∼3–6 nm in width and ∼12–20 nm in length. Their time dependent growth evolution was studied via transmission electron microscopy and coupled with our observations from the XRD analysis a growth-morphology-mechanism was proposed. The as-obtained BiVO₄ nanoparticles were deposited on an ITO coated glass substrate and the resultant films were investigated for efficiency in photoelectrochemical water splitting. The BiVO₄ nanoworms outperformed all the other BiVO₄ structures obtained at different times of growth evolution by having both the highest anodic photocurrent densities and the lowest onset potential. Subsequent EIS and Mott–Schottky analysis revealed comparatively low interfacial charge transfer resistance and a cathodic shift in the flat band potential of the nanoworms led to their better photoelectrochemical performance. Our analysis indicates that a decrease in resistive photoelectron trapping surface states associated with the BiVO₄ nanoworms leads to their excellent photoelectrochemical activity.