Controllable synthesis of 3D BiVO4 superstructures with visible-light-induced photocatalytic oxidation of NO in the gas phase and mechanistic analysis

Abstract

A surfactant-free solvothermal method was developed for the controlled synthesis of diverse 3D ms-BiVO₄ superstructures, including a flower, a double-layer half-open flower and a hollow tube with square cross-sections, via facilely adjusting the pH values with the aid of NH₃·H₂O. The effects of the morphologies of the prepared 3D ms-BiVO₄ superstructure on the photocatalytic oxidation of NO were investigated, indicating that the enhanced photoactivity was not related to the surface area, but associated with the unique morphology, surface structure and good crystallinity. Moreover, the flower-like ms-BiVO₄ photocatalyst with a more (040) reactive crystal plane exhibited higher photoactivity than those of other samples. The unique morphology helped with flushing the oxidation products accumulated on the surface of photocatalysts in the H₂O₂ system, and further improved the photoactivity. A trapping experiment was also conducted to examine the effects of the active species involved in the PCO of NO intuitively.