Preparation Of Several Chemically Modified Electrodes Based On Electrodeposition And Galvanic Replacement Reactions

Due to the unique properties,noble metal nanomaterials are widely used in the fields including environment,energy,chemistry and biology.Platinum is an important catalytic material,and the increasing platinum utilization is widely concerned.Atomic monolayer platinum catalysts have been prepared by the underpotential deposition（UPD）method combined with the galvanic replacement reactions（GRR）.However,the single layer platinum catalyst is less stable.Mn O₂is a high-performance electrode material for electrochemical studies and applications in many fields.In this thesis,we give a brief review on noble metal electrocatalysts,Mn O₂electrochemistry and GRR,and several chemically modified electrodes of noble metals and Mn O₂have been prepared on the basis of electrodeposition and GRR.The performance of these modified electrodes for the electrocatalytic oxidation of methanol and formic acid and the use as supercapacitor electrode is investigated.The main contents are as follows:1.The Mn O₂film is electrodeposited on gold modified glassy carbon electrode（Au/GCE）,Mn（OH）₂is obtained after electroreduction of Mn O₂under alkaline conditions,and the GRR between Mn（OH）₂and K₂Pt Cl₄yields.Pt _Mn-GRR/Au/GCE has high platinum utilization and excellent performance for electrocatalytic oxidation of methanol.The current density is 28.7 m A/cm _Pt²by cyclic voltammetry（-0.8V～0.8 V,50 m V/s）in 0.5 M Na OH+1 M CH₃OH solution,and the current density is 5.01m A/cm _Pt²by cyclic voltammetry（-0.2V～1.0 V,50 m V/s）in 0.5 M H₂SO₄+1 M CH₃OH solution,being superior to some Pt-modified control electrodes.2.Mn O₂-MWCNTs/Au/GCE is prepared by composite one-pot electrodeposition on Au/GCE in stirred multiwalled carbon nanotubes（MWCNTs）dispersed aqueous solution.The Mn O₂-MWCNTs/Au/GCE is characterized by scanning electron microscopy（SEM）,Raman spectroscopy,cyclic voltammetry and galvanostatic charge-discharge tests.The results show that the Mn O₂-MWCNTs/Au/GCE has the better capacitance behavior than Mn O₂/Au/GCE.3.A Ge film is electrodeposited on Au/GCE.A Pt Au binary noble metal electrode（Pt₇Au₃/Au/GCE）is prepared by GRR between Ge and H₂Pt Cl₆+HAu Cl₄（7:3 in molar ratio）.The electrocatalytic properties of the modified electrode for formic acid are investigated.The stability of the electrode and the catalytic response to formic acid is better than those prepared by bulk electrodeposited Cu-GRR and UPD Cu-GRR methods,and the addition of Au improves the antitoxic ability of the Pt-modified electrode.