Preparation Of Pt-based Alloys And Functionalized Graphene-supported Electrocatalysts And Their Performance For Methanol Oxidation Or Hydrogen Evolution

To solve the problems of energy crisis and environmental pollution,clean and sustainable power sources and devices have been developed.Nowadays,direct methanol fuel cells（DMFCs）and water splitting are two kinds of energy conversion and storage systems due to their eco-friendly and sustainability.Among them,methanol oxidation reaction（MOR）and hydrogen evolution reaction（HER）are two main half-reactions in DMFCs and water splitting system,respectively.So far,Pt is still regarded as the most approbatory electrode material for MOR and HER.However,the high dosage,high cost and scarcity of Pt hinder its further development and commercialization.Besides,Pt based catalysts also suffer from intermediates poisoning,thus reducing their activity and long-term stability for MOR.Therefore,it is urgent to explore excellent catalysts to improve the electrocatalytic performance toward MOR and HER.In this thesis,three advanced catalysts were designed based on morphology controlling and functionalized supports,and their electrocatalytic properties toward MOR or HER were systemically investigated.The obtained innovative results are as follows:（1）With five different sulfonated metal phthalocyanine（Ts MPc,M=Zn,Fe,Cu,Co,Ni）functionalized graphene（Ts MPc-G）as the supports,the Pt/Ts MPc-G catalysts were synthesized by the deposition of Pt nanoparticles on the Ts MPc-G via the hydrothermal method.The physical and chemical properties of the as-prepared catalysts were characterized by UV-visible spectroscopy（UV-vis）,thermogravimetric analysis（TGA）,Raman spectroscopy（Raman）,transmission electron microscope（TEM）,X-ray photoelectron spectroscopy（XPS）,X-ray diffraction（XRD）and electrochemical measurements.The results show that,the Ts MPc functionalization could tune the electronic state of the graphene surface,which is more beneficial for the anchoring of Pt nanoparticles,increasing the electrochemical active surface area of the prepared materials.As a result,the Pt/Ts MPc-G catalysts have higher MOR activity,stability and toxicity resistance than the Pt/G and Pt/C catalysts.（2）The ultralong and uniform tri-metal core-shell Au@Pt Ir nanowires（NWs）were synthesized by wet chemical method.With Te NWs as a sacrificial template,Au NWs was first prepared via the metal replacement method.Then,Pt Ir alloy nanoparticles were further grown on the Au NWs surface in aqueous solution to obtain the Au@Pt Ir NWs catalyst with Au as the core and Pt Ir as the shell.XRD,TEM,XPS and electrochemical tests were used to characterize the materials.The results show that the Au@Pt Ir one-dimensional nanostructure and the strong electronic interaction between Pt,Ir and Au enabled the catalyst exhibit good catalytic activity and stability as well as excellent toxicity resistance toward both MOR and HER.（3）Using H₂Pt Cl₆,Cu（NO₃）₂ and Fe Cl₃ as the metal precursors,the one-dimensional ternary Pt Cu Fe nanochains（NCs）with uniform size were synthesized by the solvothermal method.The as-prepared materials were characterized by XRD,TEM,XPS and electrochemical testing techniques.The results show that the alloying of Pt with Cu and Fe improved the electronic interaction of the catalyst and adsorption ability,and then the Pt Cu Fe NCs catalysts exhibited more excellent electrocatalytic activity and CO tolerance for methanol oxidation than the Pt Cu NCs and Pt Fe NCs catalysts under acidic conditions.