Comparative Study of Bulk and Nanoscale BiVO₄ Photoanodes in Photoelectrochemical Oxidation Reactions

Abstract Most BiVO 4 ‐based photoelectrodes are prepared using the metal‐organic decomposition (MOD) method, which produces a characteristic porous bulk BiVO 4 film. To study different photoelectrochemical (PEC) properties depending on the structure of BiVO 4 , bulk‐ and nanoscale (nano)‐BiVO 4 photoelectrodes are prepared using the same MOD method on compact‐SnO 2 (c‐SnO 2 ) and c‐SnO 2 /mesoporous‐SnO 2 electrodes, respectively. Unlike the well‐known film structure of bulk‐BiVO 4 , nanoscale dots of BiVO 4 are formed on the surface of the mesoporous SnO 2 particulate film, as confirmed by absorbance, X‐ray diffraction (XRD), and transmission electron microscope (TEM) measurements. The PEC behavior of both BiVO 4 photoanodes is examined for glycerol and sulfite oxidation reactions. The optimized bulk‐ and nano‐BiVO 4 PEC cells recorded photocurrents of 2.37 and 4.01 mA cm −2 for glycerol oxidation and of 3.28 and 5.19 mA cm −2 for sulfite oxidation, respectively. The excellent photocurrent generation ability of the nano‐BiVO 4 electrode can be used to design an ideal BiVO 4 ‐based PEC cell. Impedance analysis is performed to explain the differences in charge transfer/transport between bulk‐ and nano‐BiVO 4 PEC reactions and the reason behind the enhanced performance of nano‐BiVO 4 compared to its bulk counterpart.