Electrodeposition Ofnoble Metals By Intervention Of Underpotential Deposition Of Less Noble Metals For Electroanalysis Applications

There is a huge application space for noble metal nanomaterials in the fields including catalysis chemistry,electrochemistry and analytical chemistry due to their unique physical and chemical properties.Underpotential deposition(UPD)mainly refers to an electrochemical phenomenon that a less nobel metal is electrodeposited at a potential positive to its thermodynamically reversible potential on another less nobel metal,which has been widely studied to date.It is a worthwhile exploring project to develop nobel metal materials by the bulk electrodeposition of nobel metals intervened by UPD of less nobel metals.In this thesis,we briefly review the recent progress of nobel metal nanomaterials and UPD,study the effects of Pb or Cu UPD on bulk electrodeposition of Pt or Au,and develop high-performance Pt and Au nanomaterial thin films for catalytic electroanalysis of glucose,ethanol and As(Ⅲ)with satisfactory results.The main contents are as follows.1.Electrochemical techniques and electrochemical quartz crystal microbalance(EQCM)were used to study the UPD of Pb on a Pt electrode,and a nanoporous Pt material modified glassy carbon electrode(PtUPD/GCE)was constructed based on bulk/underpotential coelectrodeposition of Pt/Pb followed by stripping of UPD Pb.The analytical performance of glucose in neutral medium at this electrode was studied and compared with those at a Pt nanoparticles modified glassy carbon electrode(GCE)prepared by conventional electrodeposition method(Ptcon/GCE)and a Pt disk electrode.The results show that the PtUPD/GCE exhibited the best analytical performance under optimal conditions,with a linear detection range from 0.01 to 2.0 mM and a limit of detection(LOD)of 3.7μM(S/N= 3).2.Graphene oxide(GO)was reduced by cyclic voltammetry at a GCE to obtain an electroreduced GO(ERGO)/GCE,and the UPD of Cu on Pt was studied by EQCM.A nanoporous Pt material modified ERGO/GCE(PtUPD/ERGO/GCE)was constructed based on bulk/underpotential coelectrodeposition of Pt/Cu followed by stripping of UPD Cu.The electrooxidation and electroanalysis performance of ethanol in alkaline medium at this electrode was studied and compared with those at a Pt nanoparticles modified GCE prepared by conventional electrodeposition method under GO-free condition(Ptcon/GCE)and a Pt/GCE prepared by conventional one-component electrodeposition of Pt on GCE.The results show that the PtUPD/ERGO/GCE exhibited the best analytical performance under optimal conditions,with a linear detection range from 0.01 to 7 mM and a LOD of 4.8 μM(S/N=3).3.Electrochemical techniques and EQCM were used to study the UPD of Pb on an Au electrode,and a nanoporous Au material modified GCE(PtUPD/GCE)was constructed based on bulk/underpotential coelectrodeposition of Au/Pb followed by stripping of UPD Pb.The trace electroanalysis of As(Ⅲ)in acidic medium was achieved at this electrode by square wave anodic stripping voltammetry.The AuUPD/GCE exhibited a 2.5-fold larger sensitivity compared with an Aucon/GCE prepared by conventional one-component electrodeposition of Au on GCE,with a linear detection range from 0.02 to 7.0μM and a LOD of 1.4 nM(0.1 ppb,S/N = 3).