Optimization of porous BiVO 4 photoanode from electrodeposited Bi electrode: Structural factors affecting photoelectrochemical performance

In this study, BiVO4 photoanode is prepared via the chemical reaction of electrodeposited Bi metal electrode with a vanadium precursor, and the electrodeposition conditions for the Bi electrode are modified to optimize the resultant BiVO4's photoelectrochemical performance. The nucleation and growth kinetics of Bi dendrites are varied by changing the applied potential and temperature during electrodeposition. This affects the structure and morphology of Bi as well as the properties of the resultant BiVO4 after the chemical reaction. Specifically, the morphology, particle size, porosity, and facet exposure of BiVO4 are changed according to the applied potential and temperature during the electrodeposition of Bi. The decrease in particle size and increase in porosity and active facet exposure under optimized conditions are responsible for the improved photoelectrochemical performance. The photocurrent density of BiVO4 prepared under optimized condition is over 5 mA cm−2 at 1.25 VRHE for sulfite oxidation; this represents an improvement of almost 2.5 times compared to that of non-optimized BiVO4. Furthermore, the BiVO4 samples prepared under different deposition conditions only show changes in structural properties and not in other intrinsic properties such as the light absorption, energy level, and carrier density. Therefore, the structural effect of BiVO4 on the performance can be elucidated clearly.