Preparation Of AuPt, PdPt And AuPd Binary Noble Metal Nanomaterials And Their Research In Electrocatalytic Properties

Noble metal nanomaterials exhibit excellent optical,magnetic and catalytic properties due to their unique nanostructures.There are many preparation methods for noble metal nanomaterials,such as solvothermal and electrochemical methods,which are widely used for because of their controllabe,simple and fast operation.In this thesis,three kinds of binary noble metal nanomaterials have been prepared for the study of electrocatalytic activities on hydrogen evolution and oxidation of formic acid have been investigated.The main contents are as follows:1.AuPt nanomaterials.First,a gold electrode was processed to obtain a nanoporous gold film（NPGF）,and then PtCl₆^2-solution was dropped onto the surface of the NPGF.The adsorbed PtCl₆^2-was electrochemically reduced by cyclic voltammetry to obtain modified critical amount of（29.2 ng）highly dispersed Pt atoms on the NPGF（NPGF-s-Pt）,which was confirmed its high dispersion by formic acid probe molecules.The prepared electrode of NPGF-s-Pt was tested for hydrogen evolution in an acidic medium,and its hydrogen evolution performance was as good as that on the NPGF deposited with massive amount of Pt（NPGF-m-Pt）.The Tafel slope is 34 mV dec^-1,and the hydrogen evolution potential at a current density of 10 mA cm^-2was-29mV（relative to the reversible hydrogen electrode）.Cyclic voltammetry and constant potential tests showed that both of the electrodes had good durability and stability in acidic medium,and a new mechanism of NPGF-s-Pt electrode for hydrogen evolution in acidic medium is proposed.2.PdPt nanomaterials.A simple and green method was developed to preparebinaryPdPtnanomaterials.Thereducedgraphene oxide-supported PdPt alloy nanoparticles(Pd₅₀Pt₅₀0 NPs/rGO)were obtained by a two-step method.First,H₂PtCl₆,PdCl₂ and graphene oxide（GO）solutions were uniformly mixed and transferred to a pressure-tight reaction kettle,which was kept at 190℃for 2 h.Here,GO was used as a carrier of metal nanoparticles,and it had a large amount of oxygen-containing functional groups（e.g.C-O,C-OH,C-OOH）acting as a reducing agent to reduce a portion of the metal ions.Then,the remaining metal precursors were completely reduced electrochemically.The prepared Pd₅₀Pt₅₀0 NPs/rGO showed better catalytic activity than the catalysts of Pt NPs/rGO and Pd NPs/rGO for hydrogen evolution in an acidic medium.Cyclic voltammetry and constant potential tests showed that the Pd₅₀Pt₅₀0 NPs/rGO electrode had good durability and stability in acidic medium.3.AuPd nanomaterials.The catalyst of reduced graphene oxide loaded with AuPd nanoparticles(Au₅₀Pd₅₀0 NPs/rGO)was prepared by a one-step hydrothermal method.The synthesized Au₅₀Pd₅₀0 NPs/rGO catalyst has high electrocatalytic oxidation activity for formic acid.Compared with the prepared Pt NPs/rGO and Pd NPs/rGO catalysts,Au₅₀Pd₅₀0 NPs/rGO catalyst is more beneficial for dehydrogenation in electrocatalytic oxidation of formic acid,showing higher anti-toxicity and stability.