Luminescent Properties And Photocatalytic Activity Of Bismuth Molybdate Powder

In recent years, semiconductor photocatalytic technology is widely used in the treatment of environmental pollution, purification of air and water, and the use of solar energy to degrade organic pollutants, which have been paid more and more attention by people in the 21st century.Looking for a new photocatalytic material with visible light response is the key of semiconductor photocatalytic technology from the experiment to the real application. Bi2MoO6 as a member of Aurivillius oxide, due to its novel physical and chemical properties, it has important applications in ionic conductors, gas sensors, photocatalyst and solar cells. Bi2MoO6 solves the shortcoming that TiO2 can only use the ultraviolet light, and can degrade organic pollutants under the visible light irradiation.It is one of the representatives of the new visible light photocatalyst. Bi2MoO6 powder is prepared by hydrothermal method in this paper. By means of X-ray diffraction (XRD), scanning electron microscopy (SEM), gas chromatograph analysis method for preparation of structure, morphology and photocatalytic properties of the samples were characterized and analyzed. The luminescence properties of Bi2MoO6:Yb3+, Tm3+ were analyzed by fluorescence spectrometer.The main research contents include the following aspects:(1)Using Bi(NO3)3·5H2O and Na2MoO4·2H2O as raw materials, Bi2MoO6 powder was successfully prepared by hydrothermal method.We analyzed the effects of pH, temperature and time on the preparation of Bi2MoO6 powder. It is found that the pure phase Bi2MoO6 can be produced only in the acidic environment, and the alkaline environment can be generated Bi3.64Mo0.36O6.55.In the case of more than 120 degrees Celsius, Bi2MoO6 crystal can be successfully prepared, with the increase of temperature, the intensity of the diffraction peak of Bi2MoO6 powder has been enhanced.Reaction time at 16h, the preparation of Bi2MoO6 powder crystal effect is better. Increasing reaction time was not significant to the change of crystallization effect..(2)Three methods of enhancing the photocatalytic activity of Bi2MoO6 powder were analyzed.After the addition of PVP, the morphology of the samples changed greatly, it could be found that the shape of the flower globular, the particle size became smaller, so as to effectively improve its photocatalytic activity.If Bi2MoO6 powder is modified with Ag, the activity of Bi2MoO6 powder degradation of isopropyl alcohol increases.This is due to the Ag doping can increase the Bi2MoO6 light response range, but also can be due to reduce the probability of electron and hole recombination, improve the efficiency of the use of optical carriers.After F doped Bi2MoO6 powder, with the increase of the proportion of F, the photocatalytic activity gradually increased.When the doping ratio reached 0.4, the efficiency reached the highest, with the increase of the proportion of doping, the activity decreased.(3) Under the excitation of the 980nm semiconductor laser, we used the Hitachi F-4700 spectrometer to record the up conversion emission spectra of the samples. Bi2MoO6:Yb3+, Tm3+ on the conversion of emission spectra of a total of two emission peaks,480nm strong blue emission and 652nm weak red emission. The visible up conversion luminescence is blue. After comparison of different rare earth ions doping concentration of the emission spectra, Bi2MoO6:Yb3+, Tm3+ luminescent powder optimal rare earth doped ratio of Tm3+ ion concentration is 1%, Yb3+ ion concentration is 8%.By Ag modified samples, with the increase of the amount of Ag introduction, Bi2MoO6:Yb3+, Tm3+ sample luminescence enhanced and then changed to weaken. When the doping ratio of AgNO3 is 0.01,the luminescence efficiency is about 3.7 times that of no modification.The experiment found that bismuth molybdate powder has good photocatalytic and upconversion luminescence effect. By Ag Modified Bismuth Molybdate powder, due to electron hole separation points, so as to realize the enhancement of the photocatalytic effect,on the other hand,the luminescence effect is enhanced by the resonance effect of the fluorescence plasma.