Abstract

Bismuth molybdate (Bi2MoO6), as one of bismuth-based semiconductors, has aroused great interest in photocatalysis due to its layered structure, tailored morphologies, appropriate band gap, visible-light absorption. Nevertheless, the performance of Bi2MoO6 significantly depends on the synthesis approaches that control the phase purity, crystallinity and photocatalytic activity. This work focuses on a detailed investigation about the effects of hydrothermal and solvothermal synthesis approaches on phase evolution, structural features and photocatalytic performance of Bi-based molybdates for the degradation of organic pollutants when subjected to visible light irradiation. The prepared phases were verified by X-ray powder diffraction (XRD) in which hydrothermal process produced alpha-Bi2Mo3O12, whereas solvothermal process resulted in gamma-Bi2MoO6. When compared with alpha-Bi2Mo3O12, the performance of gamma-Bi2MoO6 showed improved crystallinity, a medium bandgap (similar to 2.3-2.8 eV) and excellent photocatalytic activity with a > 95% degradation of MB within 120 min. The higher performance was ascribed to the enhanced charge separation, extended absorption and definite layered structure. The optimal performance of gamma-Bi2MoO6 obtained from the solvothermal process demonstrated its potential in visible light-driven water treatment. Therefore, these results collectively reveal that effect of the synthesis process can determine the phase composition and photocatalytic efficiency towards organic pollutants.