Growth of BiVO4 Nanoparticles on a Bi2O3 Surface: Effect of Heterojunction Formation on Visible Irradiation-Driven Catalytic Performance

Heterostructured materials composed of different semiconductors can be used to decrease rapid charge carrier recombination in photocatalysts, but the development of efficient synthesis methods for these materials remains a challenge. This work describes a novel strategy for tailoring heterostructures that is based on the solubility difference between two semiconductors with at least one metal in common. The growth of BiVO4 on a preformed Bi2O3 particle was used as a model for heterojunction formation. The number of Bi2O3/BiVO4 heterojunctions was tuned using synthesis variables (temperature and V concentration) and the particle size of the preformed Bi2O3. The synthesis of the Bi2O3/BiVO4 heterostructures using Bi2O3 nanoparticles resulted in a larger quantity of heterojunctions due to the higher solubility of the nanoparticles compared to Micrometric Bi2O3, which led to a, classical heterogeneous precipitation on the preformed surfaces. The proposed growth mechanism was effective for obtaining heterostructured Bi2O3/BiVO4 semiconductors with enhanced photocatalytic performances compared to the isolated phases. The greater photoactivity of the heterostructures could be explained by the increased spatial separation in the photogenerated electron/hole pairs due to the formation of a type-II heterostructure and was observed by time-resolved photoluminescence analysis. In this case, the photogenerated electrons were transferred from the Conduction band of the p-type semiconductor (Bi2O3) to the n-type (BiVO4) semiconductor, while the photogenerated holes were transferred from the valence band of the n-type semiconductor to the p-type semiconductor.