Nanosheet-Based Bi 2 Mo x W 1− x O 6 Solid Solutions with Adjustable Band Gaps and Enhanced Visible-Light-Driven Photocatalytic Activities

Bi 2 Mo x W 1− x O 6 solid solutions with various compositions ( x = 0, 0.25, 0.50, 0.75, and 1.00) have been synthesized by a facile hydrothermal crystallization method. All the as-synthesized products are composed of nanosheets with similar orthorhombic Aurivillius layered structures. With decreasing Mo content, the thickness of the nanosheets decreases. The nanosheets begin to intergrow at x = 0.75 and further assemble into hierarchical superstructures through “oriented attachment” with even less Mo content. For the Bi 2 Mo x W 1− x O 6 solid solutions with x = 0.25, 0.50, and 0.75, the valence band is widened and the conduction band is elevated when compared with the most intensively studied Bi 2 WO 6 photocatalyst. As a result, the Bi 2 Mo x W 1− x O 6 solid solutions ( x = 0.25, 0.50, and 0.75) show narrowed band gaps of ∼2.69 eV when compared with Bi 2 WO 6 (2.94 eV) and Bi 2 MoO 6 (2.72 eV). The photocatalytic activities of the as-prepared products have been evaluated using the photodecomposition of methylene blue under visible light irradiation as a model reaction. The sample, Bi 2 Mo 0.25 W 0.75 O 6, exhibits the highest photocatalytic activity. The intrinsic layered structure, nanosheet morphology, manipulated band structure and band gap, and the W content play important roles in the photocatalytic activity. Our approach provides a facile technique to tune both the nanostructure and the band gap of photocatalysts by simply adjusting the composition of the solid solutions, leading to photocatalysts with enhanced visible light photocatalytic activity. This method may be further extended to the designed synthesis of novel and highly efficient visible-light-driven semiconductors for environmental remediation.