Investigation of the Photo-Excited Charge Carrier Dynamics in Bismuth Vanadate (BiVO4) Photoanode by the Heterodyne Transient Grating Technique

Abstract We measured the heterodyne transient grating (HD-TG) responses of the BiVO4 photoanode for the first time. We demonstrated that the responses observed in acetonitrile, an inactive solvent, consisted of the recombination arising from the surface trapped holes and the thermal diffusion component. In addition, we found two components in the responses observed in aqueous solution under the applied bias condition, which were assigned to the recombination arising from the surface trapped holes and mixed component corresponding to the competition between back electron/hole recombination and water oxidation, respectively. The observed responses showed the strong dependence of the signal intensities on the applied voltage and the retardation of the recombination, resulting from the band bending.