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zhangzhiweia

铁杆木虫 (职业作家)

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In order to characterize probable electrode reaction pathways of adsorption H on Pt(100) surface, we applied energetically the most stable configuration which was obtained from the H adsorption to map out the minimum-energy paths(MEP) using elastic band method. Here, a (4×1) surface unit cell with a slab of three layers thickness(36 Pt atoms) was chosen to model adsorption of H on Pt(100) surface(the single structure determined lattice constant of 8.324Å was used for the production of Pt(100) surface). The slab was repeated periodically with a 13.962Å of vacuum region between the slabs. Plausible intermediates for the H-Pt(100) interactions was initially optimized by placing H atoms at two different active sites on the Pt(100) surface, including “Pt-bridge site and Pt-hollow site”, corresponding to the structure of Pt(100) surface.
Obviously, the anode would lose electrons during electrode reaction. The adsorption energy and Pt-H distance for hydrogen on Pt(100) surface after optimization are presented in Table 1. The negative adsorption energy comes from the computational procedure that the geometry optimization is carried out only in no-spin-polarization calculation. Seeing from the Table 1, the adsorption energy for bridge site is larger than the hollow site’s. Namely, bridge site on the terrace is stable after geometry optimization, the hollow site on the terrace maybe the intermediate state.
Furthermore, we analyzed Pt-H distance for hydrogen on Pt(100) surface(seen from table 1), Before electrode reaction, the Pt-H distances for the hollow site and bridge site are 2.035 Å, 1.613 Å, respectively. The H-Pt distance at bridge site is shorter than that of hollow site. That is, the bridge site is more stable than another one. After electrode reaction, the Pt-H distances for the hollow site and bridge site are 2.029 Å, 1.607 Å, respectively. Zhang******* used the Morse Potential to calculate Pt-H distance at the most stable state is 1.79 Å, which result is similar to ours. It is found that the distance of Pt-H becomes shorter during the electrode reaction. By comparing the bridge sites with the hollow sites, for Pt-H distance, it shows that the latter is shorter than the former and it is indicated that the adsorption energy for the latter will be larger. In conclusion, adsorption of H on Pt(100) can take place and the best adsorption site is the bridge site.

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1楼 2010-12-15 20:51:37

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gary8812

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zhangzhiweia(金币+6, 翻译EPI+1): 2010-12-21 13:12:21

To explore probable electrode reaction pathways of adsorption H on Pt(100) surface, we applied energetically the most stable configuration obtained from the H adsorption to map out the minimum-energy paths(MEP) by using elastic band method. Here, a (4×1) surface unit cell with a slab of three layers thickness(36 Pt atoms) was chosen to simulate the adsorption of H on Pt(100) surface(the single structure determined lattice constant of 8.324Å and was used for the production of Pt(100) surface). The slab was repeated periodically with a 13.962Å of vacuum region between the slabs. Plausible intermediates for the H-Pt(100) interactions was initially optimized by placing H atoms at two different active sites on the Pt(100) surface, including “Pt-bridge site and Pt-hollow site”, corresponding to the structure of Pt(100) surface.
Obviously, the anode would lose electrons during electrode reaction. The adsorption energy and Pt-H distance for hydrogen on Pt(100) surface after optimization are presented in Table 1. The negative adsorption energy comes from the computational procedure in which the geometry optimization is carried out only in no-spin-polarization calculation. As can be seen from the Table 1, the adsorption energy for bridge site is larger than the hollow site’s. Namely, bridge site on the terrace is stable after geometry optimization, the hollow site on the terrace maybe the intermediate state.
Furthermore, we analyzed Pt-H distance for hydrogen on Pt(100) surface(seen from table 1), Before electrode reaction, the Pt-H distances for the hollow site and bridge site are 2.035 Å, 1.613 Å, respectively. The H-Pt distance at bridge site is shorter than that of hollow site. That is to say, the bridge site is more stable than another one. After electrode reaction, the Pt-H distances for the hollow site and bridge site are 2.029 Å, 1.607 Å, respectively. Zhang******* used the Morse Potential to calculate Pt-H distance at the most stable state is 1.79 Å, which result is similar to ours. It is found that the distance of Pt-H becomes shorter during the electrode reaction. Compared the bridge sites with the hollow sites, for Pt-H distance, it shows that the latter is shorter than the former and it is indicated that the adsorption energy for the latter will be larger. In conclusion, adsorption of H on Pt(100) can take place and the best adsorption site is the bridge site.