Synthesis,Characterization And Doping Mechanism Of Bimetallic Au_36-xCu_x?m-MBT?₂₄ Nanocluster

The metal nanoclusters have become a research hotspot and an irreplaceable new nanomaterial in recent years owing to well physicochemical property resulting from their smaller size.Compare to the nanoparticle,it is obvious for us to discover the advantage of metal nanoclusters,and the detail information is as bellow:(1)The smaller size(<2 nm)made them strong quantum size effect and good physicochemical property.Therefore,the metal nanoclusters have great potential application in the field of catalysis,electrochemistry,fluorescence,and biological.(2)The size of nanoclusters could be controlled through our choice of synthetic method,providing an extremely simple and convenient approach for the exploration of their growth mode;Not only,this also lay the foundation for exploring the relation between size and application.The dopping of other metal atoms(Ag,Cu,Pd,Pt and Ni etc.)could improve the physicochemical property of homogold nanocluster from recent significant studies.The doping numbers and sites of foreign metal atoms are observed but,surprisingly,the total number of metal atoms in the gold nanocluster is preserved.This is beneficial for us to study the structural,optical and electronic properties truly at atom level,and thus provides a good method to explore the application of these new alloy nanoclusters.A novel Au-Cu alloy nanocluster was synthesized with our newly developed in-situ two-phase ligand exchange method,whose crystal structure was determined from X-ray single crystal diffractometer.Au36-xCux(m-MBT)24(x=1-3,m-MBT=3-methylbenzenethiolate)nanocluster contains an face-centered cubic(FCC)M28(M=Au/Cu)metal core,which is protected by 12 bridging SR ligands and 4 same M2S3 staple motifs.The total crystal structure of Au36-xCux(m-MBT)24 bimetallic nanocluster is resemble with Au36(SPhtBu)24 reported by Jin and his workers in 2012.The Cu dopant numbers of Au36-xCux(m=MBT)24 alloy nanocluster range from 1 to 3,and the average of which is 2 revealed by X-ray single crystal diffractometer.There are 14 sites where Cu could possibly occupy,that is,8 in the motifs and 6 in the sub-surface of Au36-xCux(m-MBT)24 nanocluster.The UV-vis and MALDI-MS spectral monitoring indicates the number of Cu atoms dopant sequentially increased with the increasing amount of CuCl2 during the synthesis of alloy precursors(the amount of gold is constant.).Meanwhile,DFT calculations imply that the maximum number of Cu dopant is 3,and metal doping occurs preferentially at the staple motifs and sub-surface sites.For the systematicness and comprehensiveness of our study,thermogravimetric analysis(TGA)and X-ray photoelectron spectroscopy(XPS)were conducted to character the Au36-xCux(m-MBT)24 bimetallic nanocluster.