Nanostructure Regulation And Photocatalysis Properties Of Nonmetal Co-Doped TiO₂ Based On Self-Doping

The environment pollution and energy shortage are becoming more serious with the development of science and technology.As an environmentally friendly catalyst,TiO₂ can be activated only under ultraviolet light because of the broad band gap,while ultraviolet light accounts for a small fraction?<5%?of the solar energy.In order to extend its optical absorption to visible light region,variety of modification has been carried out.In this paper,nonmetal self-doped and co-doped TiO₂ with visible-light absorption were prepared.Sample structure,morphology,surface absorption groups,elemental composition and chemical state,optical properties were characterized by X-ray diffraction?XRD?,Raman,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,Fourier transform infrared spectroscopy?FT-IR?,X-ray energy dispersive spectroscopy?EDX?,X-ray photoelectron spectroscopy?XPS?and ultraviolet-visible spectrophotometer?UV-vis?.The results are as follows:?1?We report the preparation of visible-light responsive N-P chemical co-doped TiO₂ nanosheets combining a hydrothermal method and high temperature organic method.Increasing the {001} surface area is beneficial to its photocatalytic activity,because {001} surface is much more reactive than the thermodynamically stable {101} surface.Changing the dosage of the hydrofluoric acid can achieve the coordinated regulation of nonmetal doping and {001} facets on TiO₂.NP-TiO₂ has a much higher degradation of RhB than N self-doped TiO₂,because chemical co-doping could reduce the band gap of TiO₂ more effectively.In addition,F-adsorbed on the surface of TiO₂ nanosheets could accelerate the degradation of dyes RhB.?2?Rutile phase C self-doped TiO₂ having high visible light photocatalytic activity was prepared using hydrothermal synthesis method with nitric acid solution and TiC as precursors.Samples with different morphologies can be obtained by changing the amount of the TiC precursor.Nanorods assembled flower-like structure was obtained when the less TiC was used,because gas was easier to release;with increasing the amount of Ti C,we obtained the nanorods assembled hollow spheres,because narrowed gas passage is adverse to release the gas.Sample with flower-like structure has higher surface area,which can react with RhB more effectively.?3?C-N-S co-doped TiO₂ hollow sphere was prepared by one-step and two-step hydrothermal method.The sample synthesized by one-step method was assembled by anatase nanoparticles,while the sample synthesized by two-step method was assembled by rutile nanorods.The structure of hollow spheres has a higher surface area,while nanorod structure is in favor of the separation of electron and hole pairs.So sample two-step synthesized C-N-STiO₂ exhibit a higher photocatalytic activity.In conclusion,we realized the preparation of nonmetal self-doped and co-doped TiO₂ with higher visible-light photocatalytic activity by hydrothermal method and high temperature organic method.The modification method can be extended to other semiconductor photocatalytic systems.