Density functional theoretical studies on themethanol adsorption and decomposition on Ru(0001) surfaces.
Density functional theoretical studies on themethanol adsorption and decomposition on Ru(0001) surfaces.
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Ru(0001)表面甲醇吸附分解的密度泛函理论研究。
DOI：
10.1007/s40242-016-5416-z
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
吕存琴
中科院分区：
文献类型：
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作者：
吕存琴
采用周期性密度泛函理论（DFT）方法研究了甲醇在Ru（0001）表面上的吸附和分解过程，其中包括p（3×2）、p（2×2）和p（2×1）三个单胞，分别对应于单层覆盖度为1/6、1/4和1/2.分析了甲醇解离过程中各物种的几何构型和能量，计算了Ru（0001）表面1/2，1/4和1/6 ML覆盖度下甲醇的初始分解反应以及随后的CH 3 O和CH 2 OH的分解反应.结果表明，覆盖度对CH 3 O、CH 2 OH和CH 3的稳定吸附有一定影响，覆盖度越低，吸附越强。覆盖度对甲醇的初始分解也有影响。在Ru（0001）表面上，C-H键断裂在1/2 ML处是有利的，而C-H和O-H键断裂分别在1/4和1/6 ML处是优选的。在Ru（0001）表面1/4 ML覆盖率下，反应机理为：9 CH 3OH → 3CH 3 O +6CH 2 OH +9 H → 6CH 2 O +3CHOH+18 H → 7 CHO +COH+CH+OH+26 H → 8 CO +C+O+36 H。
Periodic density functional theory(DFT) calculations are presented to describe the adsorption and decomposition of CH3OH on Ru(0001) surfaces with different coverages, including p(3×2), p(2×2), and p(2×1) unit cells, corresponding to monolayer(ML) coverages of 1/6, 1/4, and 1/2, respectively. The geometries and energies of all species involved in methanol dissociation were analyzed, and the initial decomposition reactions of methanol and the subsequent dehydrogenations reactions of CH3O and CH2OH were all computed at 1/2, 1/4, and 1/6 ML coverage on the Ru(0001) surface. The results show that coverage exerts some effects on the stable adsorption of CH3O, CH2OH, and CH3, that is, the lower the coverage, the stronger the adsorption. Coverage also exerts effects on the initial decomposition of methanol. C—H bond breakage is favored at 1/2 ML, whereas C—H and O—H bond cleavages are preferred at 1/4 and 1/6 ML on the Ru(0001) surface, respectively. At 1/4 ML coverage on the Ru(0001) surface, the overall reaction mechanism can be written as 9CH3OH→3CH3O+6CH2OH+9H→6CH2O+3CHOH+18H→ 7CHO+COH+CH+OH+26H→8CO+C+O+36H.