Preparation And Electrocatalytic Performance Of Pt/TiO₂ Anodic Catalyst For Direct Methanol Fuel Cell

Direct methanol fuel cell?DMFC?has the advantages of high energy conversion efficiency and environmental friedliness,and has a good application prospect in the field of portable electronic products and vehicle-mounted power.Pt-based catalytic materials are the most effective DMFC anode catalysts for methanol oxidation.However,the Pt-based catalyst is easily poisoned by the intermediate product of methanol oxidation,resulting in low catalytic efficiency,and the low utilization rate of the catalyst due to agglomeration of active components during the preparation process,which is one of the reasons that hinder the commercialization of DMFC.Under the premise of keeping dosage,how to improve the activity and utilization of Pt-based supported catalyst is an important aspect of DMFC research.In this paper,using Pt as active component,TiO₂ as support,and Ti sheet as substrate,through the optimization of the preparation process and functional design of the support,the TiO₂ support Pt catalyst?Pt/TiO₂/Ti?was prepared by pyrolysis and its phase morphology and electrocatalytic properties were characterized.Based on the photacatalytic properties of TiO₂ material,the effects ofillumination on the performance of the above catalysts were also considerd.The specific research content is as follows:?1?By adding hydroxy propyl cellulose?HPC?or hydroxypropyl methyl cellulose?HPMC?dispersant to the Pt precursor,the degree of agglomeration of Pt on the TiO₂support in the catalyst prepared by pyrolysis was improved so as to improve the utilization ratio and the catalytic efficiency.The test results show that the use of dispersants not only improves the dispersion of Pt particles on the support,but also improves the electrochemical active surface area,catalytic activity and stability of Pt/TiO₂/Ti catalyst.The peak current density of the methanol oxidation catalyzed by the Pt/TiO₂/Ti catalyst prepared using the dispersantis 2.8 and 4.7 times that of the without dispersant,respectively.In addition,the catalytic performance of Pt/TiO₂/Ti catalyst for methanol oxidation is greatly improved under illumination compared without illumination.This is due to the oxidative removal of the toxic intermediates produced by the electrooxidation of methanol by hydroxyl radicals generated by photolysis of TiO₂.?2?As a catalyst support,TiO₂ has good stability,but its conductivity is far less than that of carbon material,which affects the performance of the catalyst to some extent.For this purpose,TiO₂-C composite support was obtained by doping carbon with TiO₂ using glucose and?-cyclodextrin as carbon sources,respectively.The Pt/TiO₂-C/Ti catalyst was prepared by Pt loading on it by pyrolysis.The test results show that carbon incorporation and anchoring effect of carbon increase the conductivity of TiO₂ support,reduce the charge transfer resistance,and improve the dispersion of Pt on the support surface,making the catalytic performance of Pt/TiO₂-C/Ti catalyst for methanol oxidation is significantly improved over that of Pt/TiO₂/Ti catalyst,the peak current density catalyzed by methanol oxidation is 2.9 and 2.6 times that of the latter,respectively.Meanwhile,the illumination can still effectively improve the catalytic performance of the Pt/TiO₂-C/Ti catalyst for the reasons stated above.?3?In order to further improve the performance of Pt catalyst supported on TiO₂,both dispersant and carbon doping were used to prepared catalyst.The test results show that the dispersion of Pt on the support is further improved by the use of dispersant and carbon-doped composites.The catalytic activity of the prepared catalyst for methanol oxidation has been improved again in camparsion with?1?and?2?.At the same time,the test of catalyst performance with illumination once again proves the effect of illumination on the activity of Pt catalyst on TiO₂.