Engineering the dimension and crystal structure of bismuth molybdate photocatalysts via a molten salt-assisted assembly approach

In this work, a facile molten salt-assisted assembly strategy was studied to achieve controlled synthesis of bismuth molybdate photocatalysts including Bi2MoO6, Bi6Mo2O15, Bi4MoO9 and Bi14MoO24. The transition of bismuth molybdates from Aurivillius-type to Fluorite-type could be selectively and efficiently achieved by adjusting the molten salt synthesis time. It was observed that the bismuth molybdate samples exhibited an obvious redshift in the absorption band with increasing of Bi/Mo molar ratio (from 3 to 14) in the materials, indicating a reduced band-gap. As a result, the photocatalytic activity of the Fluorite-type Bi14MoO24 sample for TC removal was higher than that of Bi2MoO6, Bi6Mo2O15 and Bi4MoO9 samples under a visible light irradiation. Furthermore, the mechanisms of phase change between Aurivillius-type and Fluorite-type as well as their band structures of the bismuth molybdates were systematically investigated in this work. This study not only provides a new strategy for the controlled synthesis of bismuth molybdates with different dimensionalities and structures, but also opens a new pathway to the design and optimization of advanced bismuth molybdates-based photocatalysts for applications in energy harvesting and environmental remediation.