Rapid Formation of a Disordered Layer on Monoclinic BiVO 4 : Co-Catalyst-Free Photoelectrochemical Solar Water Splitting.

A surface disordered layer is a plausible approach to improve the photoelectrochemical performance of TiO2 . However, the formation of a crystalline disordered layer in BiVO4 and its effectiveness towards photoelectrochemical water splitting has remained a big challenge. Here, we report a rapid solution process (within 5 s) that is able to form a disordered layer of a few nanometers thick on the surface of BiVO4 nanoparticles using a specific solution with a controllable reducing power. The disordered layer on BiVO4 alleviates charge recombination at the electrode-electrolyte interface and reduces the onset potential greatly, which in turn results in a photocurrent density of approximately 2.3 mA cm-2 at 1.23 V versus the reversible hydrogen electrode (RHE). This value is 2.1 times higher than that of bare BiVO4 . The enhanced photoactivity is attributed to the increased charge separation and transfer efficiencies, which resolve the intrinsic drawbacks of bare BiVO4 such as the short hole diffusion length of around 100 nm and poor surface oxygen evolution reactivity.