Preparation Of Two-dimensional Supported Platinum-based Catalysts And Their Catalytic Properties For Methanol Oxidation

Direct methanol fuel cell(DMFC)is a promising power source in portable devices and electronic products due to its high theoretical energy density,excellent environment-friendliness and easy transportation and storage.Platinum(Pt)have been demonstrated as high performance electrocatalysts for various fuel cells due to their anisotropic structure and unique surface properties.However,the commercialization of DMFC was hindering,because of the high cost and poor stability of Pt electrocatalyst.Therefore,developing a simple and effective way to synthesize the high efficiency,low cost,good stability anode electrocatalyst is the key to promote the commercialization of DMFC.With Pt as the main catalytic components,the introduction of a second or multiple metal elements can acquire Pt based alloy electrocatalyst,which not only reduces the preparation cost of DMFC,to some extent,also shows a higher catalytic efficiency and better stability compared with pure Pt electrocatalyst.Loading the electrocatalyst nanoparticles on supporting materials,can make nanoparticles distribute evenly,reduce the particle size.With the decrease of particle size,more catalytic active sites are exposed,and thus the catalytic efficiency are improved.Based on the above analysis,in our work,Pt based alloy electrocatalyst is taken as the main catalytic components,a variety of methods are applied to construct a series of high efficiency electrocatalyst supported on graphene,Ni-Fe LDH and Ni-Fe MMO.And through a variety of methods,we discussed the effects of composite catalysts,revealed the relationship between composites with Pt.Our work mainly consists of the following three parts:1.Facile preparation of PtPdPt/graphene nanocomposites with ultrahigh electrocatalytic performance for methanol oxidationPtPdPt electrocatalyst was synthesized by the Cyclic Voltammetry(CV)electrodeposition method on GN to acquired PtPdPt/GN nanocomposites.We explored the influence that the existence of Pd on catalytic performance of Pt,and that the GN on the formation of nanoparticles.The finding indicated that there is the synergy effect between Pd and Pt.Pd could highly improve the catalytic performance of Pt.The intermediate species such as CO could produce because of incomplete oxidation of methanol during methanol oxidation process,these intermediate species will decrease Pt catalytic performance by adsorbing on the surface of the Pt.Pd could weaken the bond strength of Pt-CO,desorb CO from the surface of Pt.GN could promote the uniform loading of nanoparticles,improve the dispersion and stability of nanoparticles.2.Highly active Pt/Ni-Fe Layered Double Hydroxide Electrocatalyst towards methanol oxidation reactionNi-Fe LDH was prepared by a plain solvo-thermal method firstly.Then Pt electrocatalyst was synthesized by a facile wet-chemical method supported on the Ni-Fe LDH.Research results showed that Pt/Ni-Fe LDH electrocatalyst showed excellent catalytic performance for methanol oxidation.The catalytic ability is two-fold higher compared with commercial Pt/C catalyst.Plentiful oxygen-containing groups exist inside and outside of Ni-Fe LDH,which could accelerate the oxidation removal of the intermediate species such as CO at lower potential,avoid poisoning of Pt electrocatalyst.3.Pt/Ni-Fe Mixed Metal Oxide Electrocatalyst for Methanol OxidationNi-Fe LDH was firstly prepared by a plain solvothermal method,subsequently calcinated at low temperature to acquired Ni-Fe mixed metal oxide(Ni-Fe MMO).Pt electrocatalyst was synthesized by a facile wet-chemical method supported on Ni-Fe MMO.Research results showed that Pt/Ni-Fe MMO electrocatalyst showed excellent catalytic performance for methanol oxidation.The Ni-Fe MMO layered structure did not change after low temperature calcination.That playing an active role to homogeneous dispersion of nanoparticles.After low temperature calcination,abundant pore structure generated inside of Ni-Fe MMO,which expedite electronic delivery,accelerate the methanol oxidation indirectly.