Studies On The Preparation And Visible-Light Catalytic Performance Of Niti-Layered Double Hydroxide-Based Material

Traditional photocatalysts usually suffer from poor carrier mobilities,low electron-hole separation efficiencies and reactive stabilities, and thus result inunsatisfactory photoactivities. Layered double hydroxides(LDHs), accompanying versatilities in chemical composition and controllableelectronic structures, are a kind of promising photocatalysts. In this dissertation, by virtue of the unique structure ofNiTi-LDH, LDH-based composite materialswithobviously enhanced carrier transfers in comparison with bare NiTi-LDH,were fabricated by incorporation of NiTi-LDH with reduced graphene oxide (RGO)or Ag nanoparticlesv/a in situ method. The resulting composites display excellent visible-light catalytic activities as well as reactive stabilities.Therefore, a series of effective composite photocatalysts were reported in this dissertation, which would provide enlightening ideas for the further visible-light-driven catalysts design.The main contents of the dissertation are as follows:(1) Based on the distinct layered structure of NiTi-LDH, NiTi-LDH/RGO composite with significantly enhanced visible-light catalysis were prepared by anchoring NiTi-LDH nanosheets on the surface of RGO via in situ growth method.Electron spin resonance (ESR) and Raman scattering demonstrate the introduction of RGO in the NiTi-LDH/RGO helps improve the separation of photogenerated electron-hole and broaden the visible-light absorption, accounting forthe excellent photocatalytic behaviorfor water splitting into oxygen under visible light irradiation(O2generation rate of 1.968 mmol·g-1 h-1 and an apparent quantum efficiency of 61.2% at 500 nm). In addation, by virtue of the immobilization of RGO, NiTi-LDH/RGO composite shows excellentphotostability than the bare NiTi-LDH powder.(2)Based on the hierarchical structure of NiTi-LDH@Fe3O4, Ag/NiTi-LDH@Fe3O4Composite photocatalytic material with highly dispersed Ag nanoparticles was fabricated by loading Ag nanoparticles on the supportNiTi-LDH@Fe3O4 material viaa photo-reduction method. Ag/NiTi-LDH@Fe3O4 displays obviously enhanced photocatalytic activity for the degradation of methylene blue solution,along with high photodegradation rate of 0.11603 min-1, about 7 times higher than that of NiTi-LDH powdered sample. This can be attributed to that the formation of thecombination between Ag nanoparticles and NiTi-LDH helps accelerate electron-hole separation. In addition, hierarchical structure accelerates the catalytic processes,includingadsorption and mass transportation of organic dye molecules in water solution.