Controlled Synthesis And Catalytic Performance Of MXene-based Photocatalysts

MXene,a new photocatalytic material,has the following advantages:good metallic properties,unique carrier anisotropic mobility,tunable band gap structure;,good stability,and surface active sites,compared with traditional catalysts.As a representative of the MXene materials,Ti₃C₂T_xMXene with its unique features and performance,on the photocatalytic degradation of dye cracking water and carbon dioxide reduction in areas such as show the excellent performance.However,subject to its low photoelectric conversion performance and response to specific active site of the problem,often need to get efficient by doped composite methods such as Ti₃C₂T_xMxene photocatalyst.Herein,two photocatalysts,Ti₃C₂T_xMxene doped with Au atom and Ti₃C₂T_xMxene supported by Ag nanoparticles were successfully prepared and applied to the aerobic oxidation of organic matter and the reduction of hexavalent uranium,respectively.While studying the structure and performance of the catalyst,the mechanism of catalytic reaction was also studied by means of theoretical calculation and electrochemistry.The main results are as follows:（1）A promising catalyst toward photocatalytic aerobic oxidations was successfully developed through doping Au atoms into Ti₃C₂T_xMXene（Au/Ti₃C₂T_x）.Impressively,Au/Ti₃C₂T_xexhibited remarkable activity under full-spectrum irradiation towards photooxidation of methyl phenyl sulfide（MPS）and methylene blue（MB）,attaining a conversion of>90%at room temperature.More importantly,Au/Ti₃C₂T_xalso manifested remarkable stability by maintaining>95%initial activity after 10 successive reaction rounds.Further mechanistic studies indicated that the oxygen vacancies of Au/Ti₃C₂T_xserved as the active centers to efficiently adsorb and activate O₂.More importantly,the doped Au atoms of Au/Ti₃C₂T_xwere conducive to the recovery of oxygen vacancies during photocatalytic process from the results of theoretical and experimental aspects.The recovered oxygen vacancies of Au/Ti₃C₂T_xcontinuously and efficiently activated O₂,directly contributing to the remarkable catalytic activity and stability.（2）We successfully constructed highly active and stable photocatalysts for U（VI）photoreduction by loading Ag nanoparticles on Ti₃C₂T_xMXene（Ag/Ti₃C₂T_x）with abundant confinement sites for U（VI）.Impressively,the U（VI）enrichment capacity of Ag/Ti₃C₂T_xwas up to 1257.6 mg/g within 120 min.Further mechanistic studies indicated that the confinement sites on Ti₃C₂T_xphase in Ag/Ti₃C₂T_xwere beneficial to the reduction of U（VI）by significantly decreasing its reduction potential.More importantly,hot electrons generated by Ag nanoparticles transferred into the confinement sites on Ti₃C₂T_xphase to efficiently reduce the adsorbed U（VI）,contributing to the remarkable performance of Ag/Ti₃C₂T_xduring U（VI）enrichment.In general,the obtained Au/Ti₃C₂T_xand Ag/Ti₃C₂T_xhave the advantages of simple preparation process,large yield,excellent catalytic performance,good stability and so on.It has a great practical application prospect and can provide a reference scheme for the solution of environmental and energy problems.