甲醇在Pt-Mo(111)/C表面上的吸附

采用密度泛函理论和周期平板模型相结合的方法, 对CH3OH分子在Pt-Mo(111)/C表面的顶位、穴位和桥位共计9种吸附模型进行了构型优化、能量计算和频率分析, 结果表明top-Pt位是较有利的吸附位. Mo掺杂后价带与导带位置均有不同程度的降低, 电子结构的变化使得Pt-Mo(111)/C的催化活性提高. 并且在考虑催化剂抗中毒性能时发现: CO在Pt(111)/C面上的吸附能比甲醇吸附能要高, CO在Pt-Mo(111)/C上的吸附能比甲醇的要低, 说明CO在Pt(111)/C面上的吸附会阻碍甲醇的吸附, 并影响催化过程的进行, 而Pt-Mo(111)/C的抗CO中毒化能力增强, 是催化氧化甲醇较好的催化剂.

Adsorption of Methanol on the Pt-Mo(111)/C Surface

The density functional theory (DFT) and self-consistent periodic calculation were used to investigate the methanol adsorption on Pt-Mo(111)/C surface. The adsorption energy, equilibrium geometry and vibrational frequency of CH3OH on four sites (top, fcc, hcp and bridge) and nine types of models on Pt-Mo(111)/C surface were predicted and the favorite adsorption site for methanol is top-Pt site. After Mo is doped, the valence band and the conduction band position are depressed, and the change of the electronic structure enables the doped PtMo(111)/C to have a higher catalytic activity. Compared with the adsorption energy of CH3OHon Pt(111)/C surface, the adsorption energy of CO is higher, and Pt(111)/C is favorable to be oxidized and lose the activity. It indicates that the adsorption of COon Pt(111)/C surface counteracts the adsorption of CH3OH, which is disadvantageous for the process of catalysis. The catalyst Pt-Mo(111)/C which is in favor of decomposing methanol is of better antipoisoning ability than that of Pt(111)/C.