Study On Anti-poisoning Ability Of Platinum-gold Binary Nanocatalyst For Methanol Oxidation

Direct methanol fuel cell（DMFC）has gradually become one of the alternative power sources in the field of power electronics because of its simple configuration,renewable energy,easy storage and high energy density.However,the selection of anodic electrocatalysts suitable for methanol catalytic oxidation（MOR）is limited,because we must consider anodic electrocatalysts that enhance methanol oxidation activity and reduce CO poisoning in the selection process,so as to further improve the performance of DMFC.Platinum（Pt）based catalysts have been proved to be the most active metal catalysts for methanol dissociation and adsorption.However,Pt based catalysts are easily poisoned by products of methanol oxidation reaction at low temperature.In addition,the high price and limited reserves of platinum metal increase the preparation cost of catalyst,which restricts the research and development of DMFC.Platinum based nanomaterials introduced by gold（Au）are of great significance for direct methanol fuel cell as anode reaction electrocatalyst because of their stability and anti-poisoning characteristics.In addition,the role of gold in platinum based nanocatalysts has also attracted extensive attention of researchers.In this paper,Pt,a catalytic metal,was alloyed with Au,which exhibits strong anti-poisoning ability,and the surface of Pt Au binary noble metal catalyst was obtained by cutting the crystal surface of the alloy.VASP software was used to calculate the adsorption energy of different proportions of Pt Au binary catalyst for poisoning molecule CO.It is explained by the change of density of states and d-band center;and evaluate the blocking effect of different catalysts on the CO path and the energy released after the end of the reaction process by combining the transition state calculation of VTST script.The detailed research methods are as follows:（1）The optimized models of pure Pt,Pt₃Au,Pt Au and Pt Au₃ were cut by Materials Studio software to obtain[111]and[110]crystal surfaces respectively.After further geometric optimization,we adsorbed toxic molecules on the these catalytic crystal surfaces with the highest catalytic performance of pure Pt and Pt Au based catalysts,analyzed different catalytic sites,and calculated their adsorption energy respectively.（2）Through the calculation of density of States and the analysis according to the calculation formula of d-band center,it is found that the d-band center of Pt is obviously positive,but the d-band center of the whole material is negative.According to the d-band center theory and Sabatier principle,the anti-poisoning ability of the system decreases with the increase of Au content in Pt Au alloy,but the decrease of the overall d-band center indicates that its ability to catalyze methanol oxidation decreases.At the same time,we also use the stress effect introduced by Au to perfectly explain the change of its d-band center.（3）In order to further clarify the specific process in the process of methanol dehydrogenation,we refer to the previous process of methanol catalysis,and according to the literature investigation,we decided to calculate the transition state of formyl dehydrogenation,a key step to distinguish CO path and non CO path,and finally make it clear that the doping of Au plays a positive role in improving the reaction energy barrier.At the same time,the release of reaction energy is reduced and the continuation of the reaction is inhibited.