DFT Theory Study Of CO Adsorption On PtRu Catalyst Surface

About the study of Direct Methanol Fuel Cell (DMFC), the problem of catalyst CO poison has attracted many attentions for many years. Improving the utility of catalyst and lowing its cast has always been an important aspect of study. Now days, most studies are mainly concentrated on two aspects: (1) finding reasonable alloy catalyst; (2) investigating the problem of the optimization of each composition in catalyst.In this paper, we construct physics model, modeling CO adsorption on the surface of PtRu alloy, hope to find the most reasonable ration of alloy composition, making CO mostly uneasy adsorb on this alloy surface. In addition, we also will compare the performance of the catalyst between (100) phase and (111) phase.Firstly, we use atom clusters to model pure Pt and PtRu alloy (100), (111) surface, calculating the CO adsorption energy on those two surface. Because the CO molecular is small molecular, we just consider the adsorbed atom and it's nearest neighbor atoms. Firstly, we calculate the CO adsorption energy on Pt (100) and (111) surface, the results are very close to the experimental results, which indicates that the model and the calculated method are reasonable and could describe the process of reaction. We also find that the surface of (111) has better performance than the surface of (100), that is CO are more uneasy to adsorbed on the (111) surface.Secondly, we model the (100) and (111) surface of some special alloy by symmetrical substitution. After calculation, we find that when we just consider the (100) surface, the alloy holding 50% Ru bear better performance of resisting CO poison than the other two alloys we calculated and the CO on this alloy surface are more easy to be activated by catalyst. As to the (111) surface, when the percentage of Ru in alloy is in the range of 37.5% to 50%, the alloy hold the best performance of resisting CO poison, similarly, the CO on this surface could be activated easily. In addition, we find that the CO adsorption energy on (111) surface are lower than that on (100) surface when we fix the atom ratio in alloy, at the same time, the bond length of M-CO and C-O on (111) surface are longer than that on (100) surface, allwhich indicate again that the (111) surface hold the better performance of resisting CO poison and could promote CO on this surface to be activated.