| Summary: | Abstract Most BiVO4‐based photoelectrodes are prepared using the metal‐organic decomposition (MOD) method, which produces a characteristic porous bulk BiVO4 film. To study different photoelectrochemical (PEC) properties depending on the structure of BiVO4, bulk‐ and nanoscale (nano)‐BiVO4 photoelectrodes are prepared using the same MOD method on compact‐SnO2 (c‐SnO2) and c‐SnO2/mesoporous‐SnO2 electrodes, respectively. Unlike the well‐known film structure of bulk‐BiVO4, nanoscale dots of BiVO4 are formed on the surface of the mesoporous SnO2 particulate film, as confirmed by absorbance, X‐ray diffraction (XRD), and transmission electron microscope (TEM) measurements. The PEC behavior of both BiVO4 photoanodes is examined for glycerol and sulfite oxidation reactions. The optimized bulk‐ and nano‐BiVO4 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‐BiVO4 electrode can be used to design an ideal BiVO4‐based PEC cell. Impedance analysis is performed to explain the differences in charge transfer/transport between bulk‐ and nano‐BiVO4 PEC reactions and the reason behind the enhanced performance of nano‐BiVO4 compared to its bulk counterpart.
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