Preparation And Photocatalytic Properties Of Monoclinic Tungsten Oxide Modified Materials

The traditional method of ammonia synthesis is Haber-Bosch method,but it not only need high temperature and pressure,but also consumed energy and caused serious pollution.However,biological nitrogen fixation is difficult to meet the demand for ammonia.Photocatalytic nitrogen fixation can be carried out at room temperature and pressure.It has been more than 50 years since titanium dioxide was used in photocatalytic ammonia synthesis.Monoclinal tungsten oxide(W18O49),as a metal oxide,had the advantages of suitable bandgap width(2.7eV)and low toxicity,and was very popular in the field of photocatalysis.However,the original catalyst was easy to recombine photogenic electron-hole and had low preparation yield,so it needs further modification to improve its performance.In this paper,the original W18O49 was prepared by solvent thermal method,and the original catalyst was modified by means of doping and compounding.Besides,the reasons for the influence of material characterization on photocatalytic performance were analyzed.The main contents were as follows:1.The urchin-like W18O49 with oxygen vacancy was synthesized by solvothermal method with anhydrous ethanol as reaction solvent and tungsten hexachloride as tungsten source.A series of W18O49 samples were obtained by doping iron,cobalt and nickel.The samples were characterized by X-ray diffraction(XRD)and scanning electron microscopy(SEM),and in order to evaluate the performance of photocatalysis,the experiment of photocatalysis effect was carried out.The results are as follows:(1)with Fe and Co doping,the photocatalytic nitrogen fixation performance of the sample is improved to some extent,but the improvement effect of Ni doping is not obvious;the doping effect of WFe-4%and WCo-2%is the best.(2)When the amount of glycol is 1 ml and the amount of catalyst is 0.08g,it has the greatest influence on the experiment of photocatalytic nitrogen fixation.(3)The specific surface area of W18O49 was increased while the crystal shape of W18O49 was not changed.2.W18O49 photocatalyst was synthesized by anhydrous ethanol solvothermal method.The original catalyst was modified by the combination of alpha Fe2O3 and Fe2O3.The photocatalytic nitrogen fixation effect and long-term stability were evaluated by Nessler reagent method,and the samples were analyzed by XRD,SEM,EDS,etc.The results are as follows:(1)After the composite modification,the photocatalytic properties of the samples were significantly enhanced.(2)Semiconductor composite can reduce the band gap width of the original Wi8O49,enhance the photoelectric properties of the composite,and inhibit the recombination efficiency of the electron hole pair.3.W18O49 catalyst prepared by solvothermal method was modified by CeO2 composite and Ce doping.The nitrogen fixation effect and long-term stability of the series of materials were evaluated by Nessler's reagent method,and their systematic experiments were tested.By XRD,BET,SEM and other characterization means,the crystal morphology and specific surface area of the product were analyzed.