Construction Of Immobilized Z-scheme Ag|AgBr/Ag/FeTiO₃ Composite Film Photocatalyst And Study On Photocatalytic Activity

In recent years,environmental pollution and energy shortage have become two major problems affecting human survival and social development.It is urgent to vigorously develop efficient environmental treatment technology and clean renewable energy.Photocatalytic technology can generate many photo-generated holes with strong oxidation and photo-generated electrons with strong reduction by using solar energy,which can degrade organic pollutants and produce hydrogen simultaneously.Thus,photocatalysis is considered as a promising method to simultaneously solve above challenges.The Z-scheme photocatalytic system constructed by combining two or more semiconductors with matching band gaps has attracted more and more attention because of its high efficiency of sunlight,redox ability and chemical stability.At present,most of the Z-scheme photocatalysts reported exist in powder state,which has the defects of low photocatalytic reaction participation,poor recyclability and low stability.The above situation can be effectively improved by adopting the new photocatalyst immobilization technology to fix one or more layers of photocatalyst film on a immobilized carrier.The use of immobilization technology can realize the close combination of different photocatalyst particles on the carrier,effectively improve the catalytic activity and reusability of the photocatalyst,but also can realize the photocatalytic oxidation and reduction on both sides of the carrier at the same time,which is conducive to obtaining pure hydrogen.In this work,a novel immobilized Z-scheme Ag|AgBr/Ag/FeTiO₃photocatalyst composite film was prepared using continuous ion layer adsorption combined with photoreduction and sol-gel spin coating methods for norfloxacin photocatalytic degradation with simultaneous pure hydrogen production.The norfloxacin degradation ratios and H₂production amounts under visible light irradiation of Ag|AgBr,Ag|FeTiO₃and immobilized Z-scheme Ag|AgBr/Ag/FeTiO₃photocatalyst composite film were compared.The effects of adsorption times of silver foil,preparation layers of FeTiO₃,light irradiation time and kinds of organic pollutants on norfloxacin photocatalytic degradation and simultaneous hydrogen production were investigated.The stability and reusability of the immobilized Z-scheme Ag|AgBr/Ag/FeTiO₃photocatalyst composite film were also studied.Additionally,the generated active species in the process of norfloxacin degradation were explored and possible mechanism of organic pollutant degradation with synchronous hydrogen production caused by immobilized Z-scheme Ag|AgBr/Ag/FeTiO₃photocatalyst composite film was put forward.Research results show that when the adsorption of silver foil is six times and the preparation of FeTiO₃layer is 3 layers,the immobilized Z-scheme Ag|AgBr/Ag/FeTiO₃composite film photocatalyst exhibited the best photocatalytic activity.Under visible light irradiation for 180 min,the norfloxacin degradation ratio is 90.16%and the hydrogen production amount reached 304.08μmol caused by Ag|AgBr/Ag/FeTiO₃composite film photocatalyst.In addition,five cycle experiment results also proved that Ag|AgBr/Ag/FeTiO₃composite film photocatalyst has higher recovery rate and good stability.Therefore,this study proposes a new method for the preparation of Z-scheme photocatalyst with great activity,which is of great practical application for achieving efficient photocatalytic degradation of organic pollutants and obtaining pure hydrogen simultaneously.Also,it has important guiding significance to improve photocatalytic activity and reuse efficiency of Z-scheme photocatalyst.