The Preparation Of YFeO₃-base Composite Photocatalysts And The Photocatalytic Activity For Organic Pollutants

In recent years,the problems of sewage and wastewater have become more and more serious.The solution of photocatalytic oxidation technology is considered the most promising approach.In this paper,focusing on perovskite compounds（YFeO₃）based materials,a series of YFeO₃/AgI,YFeO₃/AgCl,YFeO_3/SrTiO₃ and YFeO₃/La₂FeTiO₆ composite photocatalysts were preparated.The XPS、XRD、SEM、TEM、UV-vis DRS and other techniques were used to characterize the physicochemical properties of the photacatalysts.In addition,the photocatalytic activity of the photocatalysts were evaluated by using organic pollutants as probes.The reaction mechanism of the catalyst was exploded.The details are as follows.1.A series of composite new catalysts with different mass fractions of YFeO₃/AgCl-X（x=10%,30%,50%,70%,90%,95%）were prepared via microwave hydrothermal technology and in-situ precipitation method.The photocatalytic degradation activity of the nanocatalyst was evaluated by degrading the organic pollutant methyl orange.Through experiments,it was found that the degradation effect was the best when the compound amount was 90%.The degradation efficiency reached 95%within 50 min under visible light irradiation,while the degradation efficiency of catalyst YFeO₃ was only 36.4%.Through the UV-Vis diffuse reflection analysis,the composite catalyst have red shifts to absorb visible photon energy.So it’s improved the degradation efficiency.2.A series of catalysts YFeO₃/AgI-X was prepared by experiments.The photocatalytic activity of the catalyst was evaluated by using methyl orange as a probe.The degradation rate of the YFeO₃/AgI-70%composite catalyst reached 92%within 40 min of visible light irradiation,while the catalytic of the catalyst YFeO₃was only 26%at the same time.when the free radical scavenger was added,the degradation efficiency of the catalyst solution containing phenylhydrazine（superoxide radical）decreased by a maximum of 84%through capture experiments,and the main catalytically active species in the experiment was superoxide radicals.What’s more,it was found that the YFeO₃/AgI-70%composite effectively inhibited the recombination of photogenerated electrons and holes,thereby improving the photocatalytic activity.3.The nano-catalyst YFeO₃/SrTiO₃ was prepared via microwave hydrothermal technology and sol-gel method.The photocatalytic activity of the catalyst was evaluated by degradation of rhodamine B.The ability of YFeO₃/SrTiO₃-70%decomposeing RhB was 72%within 300 min irradiation of visible light,which was 3times than YFeO₃.XPS analysis showed that YFeO₃/SrTiO₃-70%composite catalyst greatly increased of the content of hydroxyl oxygen to 48.3%,and the content of adsorbed oxygen increased to 32.1%.The increase of hydroxyl oxygen and adsorbed oxygen on the surface of the catalyst can produce hydroxyl radicals and hydrogen peroxide with more strong oxidizing properties,thereby increasing the efficiency of photocatalytic degradation of organic pollutants.4.For the first time,it was proposed to preparate a composite catalyst of double perovskite compound La₂FeTiO₆ and single perovskite compound YFeO₃.The YFeO₃/La₂FeTiO₆-70%exhibited the best photocatalytic activity and the degradation rate reached 53%under 300 min visible light irradiation.It was found that the composite catalyst YFeO₃/La₂FeTiO₆-70%has the largest surface area and pore diameter through N₂-adsorption desorption isotherms test,which provides more active sites for photocatalytic reaction and more adsorption RhB,thereby improving the degradation efficiency of the catalyst.