The Preparation,Photocatalytic Properties Of Nickel Containing Vanadate And Molybdate Materials

At present,photocatalytic materials have been developed in the field of degradation of organic pollutants and decomposition of water,which can provide a feasible solution for environmental and energy problems.Among them,the most widely studied photocatalytic materials,TiO2 and ZnO,are ultraviolet-light-driven materials which can't make the best of sunlight.In this paper,nickel-containing vanadates and molybdates were selected as the researched object.The optical properties of the vanadates and molybdates and the hybridization of nickel ion in the semiconductor are beneficial for the materials'photocatalytic activities.The different nickel-containing vanadates and molybdates in this paper were prepared by the Pechini method.X-ray powder diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS)(UV-VIS),specific surface area(BET)and photocatalysis were used to characterize the structure and photocatalytic properties of the samples.In chapter 3,K2Ni(VO3)4 nanoparticles were prepared by the Pechini method.All the diffraction peaks in XRD pattern can be well indexed on the basis of the monoclinic structure of K2Ni(VO3)4.No impurity lines can be observed.The particles reveal the formation of spherical grains of nanonature.The specific surface area was high.UV-Visible Spectra of the sample revealed the sample was a visible-light-response material with a band gap of 2.08 eV.XPS test showed that the valence state of Ni in the sample existed in the form of Ni2+ and the valence state of V existed mainly in the form of V5+.There might be a large amount of oxygen vacancy in the crystal structure.K2Ni(VO3)4 was an efficient visible-light-response photocatalytic material by the photocatalytic experiment.In chapter 4,AgCa2Ni2V3O12 powders were prepared by the Pechini method on the base of citrate-complexation route.All the XRD peaks were well indexed on the basis of cubic AgCa2Ni2V3O12.No impurity lines can be observed.The results of SEM and TEM showed AgCa2Ni2V3O12 with a nanoparticle morphology consisting of roughly spherical grains with smooth surfaces.Brunauer-Emmett-Teller(BET)measurement shows that the nanosample had a high specific surface area.UV-Visible Spectra of the sample revealed the sample was a visible-light-response material with a band gap of 2.16 eV.XPS test showed that the valence state of Ni in the sample existed in the form of Ni2+,and the valence state of V existed mainly in the form of V5+.The degradation rate of methylene blue by AgCa2Ni2V3O12 particals was tested under visible light irradiation,which demonstrated AgCa2Ni2V3O12 was an efficient visible-light-response photocatalytic material.In chapter 5,Na2Ni(MoO4)2 nanopowders was prepared by the Pechini method on the base of citrate-complexation route.The o'bserved diffraction peaks of Na2Ni(MoO4)2 particles well matched with the standard card PDF#31-1316.No impurity lines were observed.The sample crystallized in the irregular ball-like particles,which presented some aggregations.UV-Visible Spectra of the sample revealed the sample was a visible-light-response material with a band gap of 2.07 eV.The degradation rate of methylene blue by Na2Ni(MoO4)2 particals was tested under visible light irradiation.The degradation rate of the sample was reached more than 90%and the kinetic constant k ?0.02583 min-1,which demonstrated Na2Ni(MoO4)2 was an efficient visible-light-response photocatalytic material.Three repetitive operations of Na2Ni(MoO4)2 for photocatalytic degradation of MB.It can be seen that the degradation percentage of MB maintains a small loss of the photocatalytic efficiency.In chapter 6,Li2Ni2(MoO4)3 nano-powders were prepared by the Pechini method on the base of citrate-complexation route.The XRD picture well matched with the standard card PDF#31-0731.No impurity lines were observed.The sample crystallized with the irregular nano-particles.The particles revealed the formation of spherical grains of nano nature with an average size of 50 nm.UV-Vis absorption spectroscopy of the Li2Ni2(MoO4)3 nano-powders showed Li2Ni2(MoO4)3 had the strongest absorption in the visible light wavelength,and the band gap of the sample was estimated to be 2.07 eV.The photocatalytic activity of Li2Ni2(MoO4)3 was characterized by the degradation rate of methylene blue solution under visible light irradiation.The results showed that the degradation rate could reach to 90%in 60 min and the kinetic constant k = 0.031 min-1,which demonstrated Li2Ni2(MoO4)3 has a high photocatalytic activity.In this paper,we studied the properties of nickel-containing vanadates and molybdates as photocatalytic materials.Vanadate and molybdate have special optical properties as potential optical materials.This paper researched their excellent photocatalytic activities which can effectively degrade organic dyes under visible light irradiation.And the work in this paper find a new thought for the further development of vanadate and molybdate photocatalytic materials.