Synthesis And Properties Of Metal Doping And Its Co-doped TiO₂ Photocatalytic Materials With Nitrogen

In 1972,photocatalytic hydrogen production was realized on Ti O₂,and since then semiconductor photocatalysis had become the focus of research.However,most photocatalysts have limitations:It is difficult to fully absorb and utilize visible photon energy for most photocatalysts;It is difficult to satisfy the potential of the photocatalytic reaction system at the same time as the conduction band bottom and the valence band top of the catalyst;The recombination rate of photo-induced carrier is still high,and the lifetime of it is to an urgent needt.Ti O₂ as a photocatalyst has been arousing strong interest in the fields,which includes degradation of organic pollutants,hydrogen production by photolysis,and photoelectric conversion.However,like most photocatalysts,Ti O₂ has a large band gap?about 3.2 e V?,and responds only to the ultraviolet region,which greatly limits its utilization of sunlight.At present,the conventional method is to modify the Ti O₂ by doping ions,and reduce the forbidden band width to make it respond to visible light.In this study,a series of metal?Ni?Cu?Co?Fe?doped Ti O₂ photocatalysts were prepared by solid phase method,and Ni and N blended doped Ti O₂ photocatalysts were prepared.XRD,UV-Vis,FT-IR,PL,BET,SEM-EDS were used to characterize the structure,and the visible light activity was tested by photocatalytic degradation of methyl orange and photolysis water.The results show that the photocatalytic activity of metal?Ni?Cu?Co?Fe?doped Ti O₂ and Ni and N co-doped Ti O₂ is obviously improved.Specific research content and innovations are as follows:A series of metal?Ni?Cu?Co?Fe?doped Ti O₂ photocatalysts were prepared by solid phase method.Some factors have been investigated,which inclued metal species,doping metal concentration and calcination temperature.UV-vis spectra shows that all of the metal-doped Ti O₂ samples absorb strongly in the visible region.Methyl orange photolysis test showed that several metal doped samples showed good photocatalytic activity.X-ray diffraction pattern?XRD?and Fourier transform infrared spectroscopy?FT-IR?can be used to determine that Ni has been doped into the Ti O₂ lattice.SEM-EDS showed that the sample contains a certain proportion of metal doped metal elements,and proved that the metal elements have been doped into the Ti O₂ lattice.The specific surface area and pore size distribution of Ni-doped samples were characterized by physical adsorption?BET?.Fluorescence spectroscopy?PL?showed that the doped sample had a low fluorescence intensity.The ratio of 0.5 doped Ti O₂ at 500°C has the strongest catalytic activity under visible light.In the photolysis hydrogen production test,the rate has reached a maximum of 4.01 mmol·g^-1·h^-1.In the degradation test of methyl orange,only 9.98%of methyl orange remained after irradiation for 30 minutes under a 350 W xenon lamp.Ni and N blended doped Ti O₂ photocatalyst was synthesized by sol-gel method,first non-metal N was doped,and then metal Ni was doped by solid phase.The effects of different Ni doping ratios on the photocatalytic properties of the samples were investigated.The results of water splitting and photocatalytic degradation of methyl orange showed that the samples exhibited stronger visible light photocatalytic effects.XRD shows that the doping of non-metallic N is beneficial to improve the crystallinity of anatase.The UV-vis diffuse reflectance absorption spectrum?UV-vis?indicates that the blended doped Ti O₂ absorbs strongly in the visible region.The fluorescence spectrum?PL?showed that the fluorescence intensity of the Ni and N blend doped samples generally decreased,indicating that the recombination rate of photogenerated carriers decreased.In the photolysis hydrogen production test,Ni/N-Ti O₂?0.3?has the highest hydrogen production rate,up to 4.87mmol·g^-1·h^-1.Photocatalytic degradation of methyl orange,Ni/N-Ti O₂?0.3?has the highest degradation effect,leaving only 9.45%methyl orange.Either hydrogen production rate or methyl orange degradation,it is better than single metal Ni doping,which is the result of metal-nonmetal doping interaction.