Preparation And Electrochemical Properties Of Platinum-nickel Catalysts Supported On Carbon Nanotubes

Direct methanol fuel cell?DMFC?,as an electrochemical device which can directly convert chemical energy into electrical energy,has the advantages of high energy density and simple structure.Pt-based catalyst is the core component of DMFC,which can accelerate the electrochemical reaction kinetics.However,the high price and poor stability greatly limit the application of Pt-based catalyst and the development of DMFC.In order to solve the above problems,this work proposes a catalyst preparation strategy of PtNi catalyst formed by Ni and Pt and taking carbon nanotubes?CNTs?as the carrier.Firstly,Materials Studio?MS?was used to study theoretically the adsorption behavior of ionic liquid at the interface of CNTs,and the influence of PtNi catalyst on the methanol oxidation path,so as to guide the preparation of PtNi/CNTs catalyst by electrodeposition method.Utilizing theoretical research to guide the experiment can shorten the experimental period;The preparation of PtNi catalyst can give full play to the advantages of binary materials to form a synergistic effect.Electrodeposition process has the advantages of strong controllability and good stability.Firstly,the adsorption behavior of ionic liquids composed of choline chloride and urea at the interface of CNTs was studied by means of quantum chemical calculation and molecular dynamics simulation.The Reline?the choline chloride and urea ratio of 1:2?has the high E_HOMOOMO value and lower?E which tend to contribute electrons to CNTs,forming rapid absorption,and promote electron transfer between molecular orbitals,improving the adsorption stability.At the same time,MD simulation confirmed that the interfacial adsorption of Reline on the surface of CNTs was stable.Therefore,Reline can be an ideal solvent for electrodeposition of PtNi catalyst.Secondly,the influence of different catalyst systems of Pt and PtNi on the methanol oxidation reaction path was studied by using quantum chemical calculation.The results showed that the Pt?111?-1,2,3Ni-4Pt catalyst can be spontaneous except that the formation of*CHOH+2H⁺+H₂O which needs to overcome the lower energy barrier.Therefore,it is an ideal catalyst configuration,which can be used as a target to regulate the process conditions to prepare high-performance PtNi catalyst.PtNi/CNTs catalysts were prepared by electrodeposition on CNTs supported by carbon paper in ionic liquids.Firstly,the influence of different temperature on electrodeposition behavior of PtNi catalyst was studied.The influence of different potential,current density,time,temperature and main salt concentration on the morphology and electrochemical performance of catalyst.The results showed that Ni polarization potential shifted negatively and PtNi polarization potential shifted positively with the increase of temperature.At the time of constant potential deposition,SEM test showed that the PtNi catalyst obtained at 1.5 V potential was evenly distributed and porous,and the particle size of the catalyst increased with the increase of deposition time.The increase of temperature promoted the particle growth of PtNi catalyst,and the specific surface area was larger at 70?.At the time of constant current deposition,the PtNi catalyst prepared at different current densities had smaller particle size and better catalytic performance,stability and CO toxicity resistance.PtNi/CNTs catalyst was prepared by chemical reduction with the method of sodium borohydride reduction,which was mainly to optimize the catalyst performance by changing the main salt concentration ratio.It was found that Pt₁Ni₁/CNTs catalyst had better anti-Co toxicity performance.At the same time,PtNi/CNTs and PtNi catalysts with PtNi salt ratio of1:1 were prepared,and the results showed that the synergistic effect of Pt and Ni in catalysis was observed.Meanwhile,CNTs contributed to improve the activity,stability and anti-Co toxicity of catalysts.