Preparation And Photocatalytic Properties Of Two-dimensional MXene（Ti₃C₂） Composites

With the rapid development of social industry,a large number of untreated chemical pollutants are discharged into rivers and lakes,causing serious water pollution problems,heavy metal ionsand and organic pollutants from industry will seriously harm human health.Photocatalysis is an effective technology to solve the problem of water pollution,but traditional photocatalysts have many disadvantages,such as wide band gap,limited visible light utilization and finite photocatalytic efficiency.Therefore,it is necessary to exploit new photocatalysts with high efficiency,energy saving and environmental protection.Due to unique layered structure,excellent conductivity,hydrophilicity and stability,the novel graphene-like two-dimensional material Ti₃C₂MXene can be used as an co-catalyst for the modification of semi-conductive photocatalyst.Therefore,three kind of environmentally-friendly visible photocatalysts were synthesized by simple and controllable methods in this paper,and they were compounded effectively with Ti₃C₂ MXene,which is to obtain higher performance composite photocatalyst materials and reveal the photocatalytic mechanism of removing organic pollutants and heavy metal ions.First of all,the two-dimensionalα-Fe₂O₃ nanosheets was prepared by hydrothermal method.At the same time,two-dimensional layered Ti₃C₂ MXene has been successfully prepared by MAX phase ceramics,and Under the condition of ultrasonic assisted,α-Fe₂O₃/Ti₃C₂ MXene composite photocatalytic materials have been synthesized under the condition of ultrasonic assisted.In this paper,the morphology,crystal structure,light trapping ability,surface atomic chemical state and visible light catalytic performance ofα-Fe₂O₃/Ti₃C₂ MXene composites were systematically studied,and a possible charge transfer mechanism was proposed.The results show that a large number of heterostructures have been obtained due to the combination of two-dimensionalα-Fe₂O₃ and Ti₃C₂ MXene,which can effectively improve the visible light absorption ability and photogenerated electron hole separation efficiency ofα-Fe₂O₃.After 120 minutes of visible light irradiation,the degradation rate of Rhodamine B byα-Fe₂O₃/Ti₃C₂ MXene composite can reach 98%,and after four catalytic cycles,the degradation rate can still be maintained at 95%,showing good photocatalytic activity and cycle stability.Secondly,magneticα-Fe₂O₃/ZnFe₂O₄heterojunction was synthesized by one-step hydrothermal method,and magnetically separatedα-Fe₂O₃/ZnFe₂O₄@Ti₃C₂ MXene photocatalyst was synthesized by ultrasonic assisted self-assembly method.The morphology,crystal structure,light trapping ability,surface atomic chemical state and visible light catalytic performance of the catalyst were systematically studied in this paper.The results show that it is conducive to the transfer of photogenerated electrons and effectively inhibits the recombination of photogenerated electrons and holes due to the good conductivity of Ti₃C₂MXene.After 150 minutes of illumination,the degradation rate of Rhodamine B forα-Fe₂O₃/ZnFe₂O₄@Ti₃C₂ MXene can reach more than 98%,and the reaction rate is 2.94 times that of magneticα-Fe₂O₃/ZnFe₂O₄.After four cycles of test,the degradation rate is still above 90%.In addition,the adsorption properties of Cr（VI）forα-Fe₂O₃/ZnFe₂O₄@Ti₃C₂ MXene composite are good.In the end,BiOI was successfully deposited on the surface of two-dimensional Ti₃C₂MXene to obtained two-dimensional layered BiOI/Ti₃C₂ MXene composites by one-step hydrothermal method.The morphology,crystal structure,light trapping ability,surface atomic chemical state and visible light catalytic performance of the catalyst were systematically studied in this paper.The results show that BiOI was deposited on two-dimensional nanosheets of the layered Ti₃C₂MXene.After 50 minutes of illumination,the degradation rate of Rhodamine B for BiOI/Ti₃C₂ MXene composite can reach more than 99%.After five cycles of testing,the degradation rate can still maintain more than 95%.In addition,compared with pure BiOI,BiOI/Ti₃C₂ MXene composite also shows better catalysis in photocatalytic reduction of Cr（VI）.