AgBr quantum dots (QDs) were decorated on the surface of Bi₂WO₆to form a novel AgBr/Bi₂WO₆heterojunction. The enhancement of catalytic efficiency of AgBr/Bi₂WO₆heterojunctions relative to pure Bi₂WO₆could be associated to differences in their lifetime as holes and electrons, and to valence and conduction band positions.

Spherical Bi₂WO₆ nanoarchitectures with scale of 2–4 μm were prepared by a hydrothermal reaction using bismuth nitrate and ammonium tungstate as raw materials. Ag was deposited on the surface of Bi₂WO₆via a following facile photoreduction process. The as-prepared samples were characterized by UV-Vis-DRS, BET, XRD, XPS, FE-SEM, and HR-TEM. The results revealed that the monodispersed metallic Ag nanoparticles with average size of 10–15 nm were deposited on the surface of the spherical Bi₂WO₆ nanoarchitectures. The photocatalytic activities of the samples were evaluated by the photodegradation of RhB and thiophene under visible light irradiation. The results showed that Ag loading greatly improved the photocatalytic activity of Bi₂WO₆, and the content of loading silver has an impact on the catalytic activity of Bi₂WO₆. The 0.5at%Ag-loaded Bi₂WO₆ sample exhibited the best photocatalytic activity in both the decolorization of RhB and desulfurization of thiophene. In addition, the mechanism for the enhancement of the photocatalytic activity of Ag-loaded Bi₂WO₆ was also investigated by comparison of their PL spectra.

Uniform hierarchical multilayered Bi₂WO₆ architectures were synthesized by a facile template-free hydrothermal process, and their synthesis conditions and formation mechanism were carefully investigated. XRD, XPS, FE-SEM, and HR-TEM techniques were employed to determine their phase composition, morphology and microstructure. Nitrogen adsorption and desorption isotherms were conducted to examine the specific surface area and the pore nature of the as-prepared sample. The results show that the as-prepared Bi₂WO₆ architectures consist of secondary nanoplates and have a mesoporous nest-like morphology with a diameter of 3–4 μm, and have very large specific surface areas. The largest surface area of 47.72 m² g⁻¹ is achieved when synthesized at 190 °C for 2.0 h. Furthermore, the Bi₂WO₆ samples were fabricated into a gas sensor, and the experimental results showed that the samples exhibited high sensitivity and a fast response–recovery to ethanol gas at lower temperatures (300 °C). For 100 ppm ethanol, the sensitivity of the best sensor (GS2) was 34.6, which is about 3-fold higher than the reported mesoporous ZnO based gas sensor because its mesoporous structure provided a high surface-to-volume ratio and surface accessibility for the ethanol. A plausible enhancement gas responding mechanism of the nest-like Bi₂WO₆ sensors was also proposed based on the structure and response–recovery properties.