Study On Preparation And Photocatalytic Properties Of Tin-based Composite Photocatalyst

Semiconductor is an emerging technology that converts inexplicable solar energy into chemical energy,which is considered to be a mitigating and even new solution to the world's energy crisis and environmental pollution.So far,researchers have found a large number of semiconductor materials with photocatalytic activity,in which tin-based photocatalytic materials have attracted much attention due to their wide range of sources,low production cost and simple synthesis process.However,there are still some technical bottlenecks in the preparation and application of tin-based photocatalytic materials,such as low photocatalytic activity,high carrier recombination efficiency and poor photocatalytic cycling stability.To discuss these problems,this work chooses tin-based photocatalytic materials in the most representative of tin bismuth?Bi₂Sn₂O₇?,tin zinc?Zn₂SnO₄?and tin disulfide?SnS₂?were studied systematically,the following conclusions are drawn:?1?Zn₂SnO₄-reduced graphene oxide?rGO?composite photocatalytic materials were prepared via in-situ hydrothermal synthesis method.The effects of the addition of graphene oxide?GO?on the photocatalytic activity of Zn₂SnO₄-rGO composites were systematically studied.Experimental results showed that the visible photocatalytic activity of Zn₂SnO₄-rGO composite photocatalyst was higher than that of pure Zn₂SnO₄.Moreover,it increased firstly and then decreased with increasing the usage amont of graphene oxide?GO?.In addition,when the mass fraction of rGO was 4wt%,the photocatalytic activity of as-prepared composites reached the maximum value 99% in 240 min.UV-Vis DRS and PL test results showed that the addition of rGO could narrow the band gap of Zn₂SnO₄ and improved its photocatalytic activity.?2?In this part,SnS₂-BNNs composite photocatalytic materials were successfully loaded on surfaces of the low-layer boron nitride nanosheets?BNNs?by solvothermal method.The structure,morphology and optical properties of SnS₂-BNNs composites were characterized by XRD and UV-Vis DRS,respectively.The effects of the addition of BNNs on both the photocatalytic activity and stability of the composites were systematically studied.Experimental results showed that as-prepared SnS₂-BNNs composites could not only improve the photocatalytic activity of SnS₂-BNNs,but also the stability of SnS₂-BNNs.When the usage amount of BNNs was 10wt%,the photocatalytic activity of SnS₂-BNNs composites was the highest about 93% in 210 min.Moreover,it also possessed good cycle stability.The photocatalytic mechanism of the composites was analyzed by UV-Vis DRs and PL.Experimental results showed that the addition of BNNs could narrow the bandgap width of SnS₂ and improved the catalytic activity.?3?In order to discuss the performance of Bi₂Sn₂O₇ and its application in the future,the heterogeneous Bi₂Sn₂O₇-Ag₂CrO₄ composite photocatalytic materials were prepared in this work.The as-prepared composite photocatalytic materials were characterized by XRD,TEM and UV-Vis DRS,respectively.The mechanism of the as-prepared Bi₂Sn₂O₇-Ag₂CrO₄ composite photocatalysts with high catalytic activity was dicussed.Moreover,the influences of Bi₂Sn₂O₇ content on the simulation of pollutant rhodamine B under visible light degradation were analyzed.Experimental results showed that the photocatalytic activity of the composite photocatalytic materials was significantly improved compared with that of Bi₂Sn₂O₇ and Ag₂CrO₄ in a single phase.When the usege amount of Bi₂Sn₂O₇ was 0.45 g,the visible light photocatalytic activity of rhodamine B was 100% in 120 min.UV-Vis DRS and other characterization results showed that the construction of Bi₂Sn₂O₇ and Ag₂CrO₄ heterostructures was the main reason to inhibit photogenerated recombination and then improve photocatalytic activity.?4?Bismuth stannate?Bi₂Sn₂O₇?,as the precursor,was synthesized via a hydrothermal method.Moreover,GO was prepared by a modified Hummers method.On this basis,graphene/bismuth@stannic oxide photocatalytic compound was synthesized via a hydrothermal.These as-prepared samples were characterized by X-ray diffraction,Transmission electron microscope,UV-Vis diffuse reflectance spectra,respectively.The mechanism of the reduction of Bi₂Sn₂O₇ was discussed.In addition,the influences of the useage amount of Bi₂Sn₂O₇ on the performances of the 3D photocatalytic compound were evaluated by taking the test of photoca talytic activity.Experimental results showed that when the usege amount of Bi₂Sn₂O₇ was 300 mg,the as-prepared composites possessed the greatest photocatalytic activity,and the photodegradation efficiency of rhodamine B ws more than 90% in 180 min.