Optical control and in-situ detection of trap carrier dynamics in BiVO4 photoanodes for solar water splitting

The increasing demand for efficient solar water splitting devices calls for a mechanistic understanding of trap carrier dynamics in actual working photoelectrodes. Here, we design a pump-push-photocurrent experiment to optically manipulate and detect the in-situ dynamics of trap carriers in a model photoelectrochemical cell comprising monoclinic bismuth vanadate (BiVO4) as the photoanode. We show that a near-IR (1064 nm) push pulse can be used to reactivate the pump-induced electrons that are trapped by oxygen vacancies. Meanwhile, the effect of oxygen vacancies on carrier transport is strongly affected by external bias condition. These studies enable us to better understand the role of defects in the performance of BiVO4 photoanodes, and could be used to guide the design of other promising photocatalysts.