Electrochemical Study On Underpotential/bulk Codeposition Of Noble Metal Thin Films

Noble metal nanomaterials have attracted much attention in the fields of environment,chemistry,materials,energy,life science,and analys is/detection due to their unique properties.Obviously,studying new methods for preparing noble metal nanomaterials is of notable significance.The underpotential deposition method can be used to deposit monolayer or submonolayer ultrathin materials on the surfaces of conductive materials such as noble metals to endow the materials with new properties.In this thesis,after a brief review on noble metal nanomaterials and underpotential deposition,noble metal Pt and Au film modified electrodes are developed by metal underpotential/bulk codeposition,and used for electrocatalys is and electroanalysis of some organic small molecules（methanol,formaldehyde and glucose）.The main contents are as follows:1.The electrochemical behavior of Pb on the disk Pt electrode was studied by electrochemical technique.A Pt_Pb-UPD-modified glassy carbon electrode(Pt_Pb-UPD/GCE)was prepared by Pb-underpotential/Pt-bulk codeposition and a subsequent Pb dissolution step.The relevant electrodes were characterized by electrochemistry,scanning electron microscopy.The electrocatalytic performance on Pt_Pb-UPD/GCE for methanol oxidation in alkaline medium was studied and compared with those on the nano-platinum modified glassy carbon electrode prepared by Pb/Pt bulk codeposition and the platinum-plated glassy carbon electrode.Under optimal experimental conditions,Pt_Pb-UPD/GCE has the largest oxidation peak current（9.6 m A）and Pt-area specific electrocatalytic activity(SECA_a=39 m A cm_Pt^-2)for methanol.2.The electrochemical behavior of Bi on the disk Pt electrode was studied by electrochemical technique.A Pt_Bi-UPD-modified glassy carbon electrode(Pt_Bi-UPD/GCE)was prepared by Bi-underpotential/Pt-bulk codeposition and a subsequent Bi dissolution step.The relevant electrodes were characterized by electrochemistryand scanning electron microscopy.Formaldehyde analysis performance on Pt_Bi-UPD/GCE under alkaline condition was investigated and compared with those on Pt-modified glassy carbon electrode prepared by Bi/Pt bulk codeposition and Pt-plated glassy carbon electrode.The results show that Pt_Bi-UPD/GCE has the largest electrocatalytic response to formaldehyde.Pt_Bi-UPD/GCE potentiostatically at-0.35 V vs SCE gives a LDR from 0.01 to 9.8 m M with a sensitivity of 0.268mA μM^-1 cm^-2 and a limit of detection（LOD）of 1.1mM（S/N=3）,being better than many literature results.3.The electrochemical behavior of Pb on the disk Au electrode was studied by electrochemical technology.An Au_Pb-UPD-modified gold(Au_Pb-UPD/Au)electrode was prepared by Pb-underpotential/Au-bulk codeposition and a subsequent Pb-dissolution step.The relevant electrodes were characterized by electrochemistryand scanning electron microscopy.The electrocatalytic performance on Au_Pb-UPD/Au electrode for glucose in alkaline medium was studied and compared with those on Au-modified Au electrode prepared by Bi/Pt bulk codeposition and Au-plated Au electrode.Under optimal conditions,Au_Pb-UPD/Au electrode shows excellent sensing performance with a LDR from 0.0003 to 0.56m M in the low concentration range,a sensitivity of 266mA m M^-1 cm^-2,and a LOD of 0.3mM（S/N=3）and a LDR from 0.56 to 12.8 m M in the high concentration range.