Enhancement in the photoelectrochemical performance of BiVO4 photoanode with high (040) facet exposure.

ABSTRACT

Morphology and geometrical dimensions play crucial roles in the photoelectrochemical (PEC) performance of bismuth vanadate (BiVO4) for water splitting. Decahedral BiVO4 was synthesized through a facile hydrothermal process, which exhibited superior charge injection efficiency to the nanoporous counterpart prepared by the traditional method. More importantly, the crystal size and facet proportion of BiVO4 decahedrons were facilely controlled. The charge separation efficiency can be significantly improved with a reduction in the crystal size and an increase in (040) facet exposure. A new method was developed for rate law analysis: illumination intensity-modulated oxygen evolution reaction rate versus open circuit potential difference, which suggested that the surface reaction kinetics was not affected by facet regulation. Furthermore, after decorating the FeOOH and NiOOH as dual oxygen evolution cocatalysts, an enhanced photocurrent density of 3.2 mA cm-2 at 1.23 V versus reversible hydrogen electrode and interfacial charge injection efficiency of 97.0% can be reached. Our work inspires the development of facet-regulated BiVO4 photoanodes with high charge injection efficiency in the PEC field and provides a feasible route to enhance its charge separation efficiency.