Study On Controllable Synthesis And Photoelectrochemical Properties Of Visible Light Photocatalysts For Bismuth

Bismuth ferrite is a promising visible-light-driven photocatalyst. As a typical bismuth ferrite, Bi2Fe4O9 with a band gap around 2.0 eV shows visible-light photocatalytic performance. However, the photocatalytic efficiency of Bi2Fe4O9 is still very low, which is closely related to the surface status of Bi2Fe4O9. In this dissertation, on the basis of reactive facets synthesis, morphology controlling and surface modification, we mainly focus on the surface atomic structure engineering and charge transfer improvement in order to enhance the photocatalytic performance. Bi2Fe4O9 with a high percentage of(001) facets and Bi2Fe4O9/reduced grapheme oxide(Bi2Fe4O9-RGO) composite materials were synthesized. These materials were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM), transmission electron microscope(TEM) and X-ray photoelectron spectroscopy(XPS) techniques. In addition, the photoelectrochemical properties was investigated under visible light irradiation.Microcubes and microplatelets Bi2Fe4O9 were synthesized with NaOH as morphology controlling agent via a hydrothermal process. HRTEM images confirmed that the microplatelets Bi2Fe4O9 showed a larger percentage of(001) facets than that of microcubes. The photogenerated current density of microplatelets Bi2Fe4O9 was enhanced significantly compared to that of microcubes Bi2Fe4O9 due to the more reactive facets exposing.We developed a novel way to synthesize ultrathin Bi2Fe4O9-RGO composites by using graphene oxide as a template. As a result of morphology controlling, surface modification and reducing of surface charges recombination, the existence of reduced graphene oxide on the surface of Bi2Fe4O9 significantly affected the photoelectrochemical activities of Bi2Fe4O9 under visible light irradiation. Bi2Fe4O9-RGO composites show superior photocatalytic activity towards photoelectrochemical water oxidation.