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采用密度泛函理论(DFT)考察了Pt(100)、(110)、(111)三种表面氢原子的吸附行为,计算了覆盖度为0.25 ML时氢原子在Pt三种表面和M-Pt(111)双金属(M=Al,Fe,Co,Ni,Cu,Pd)上的最稳定吸附位、表面能以及吸附前后金属表面原子层间弛豫情况.分析了氢原子在不同双金属表面吸附前后的局域态密度变化以及双金属表面d带中心偏离费米能级的程度并与氢吸附能进行了关联.计算结果表明,在Pt(100),Pt(110)和Pt(111)表面,氢原子的稳定吸附位分别为桥位、短桥位和fcc穴位.三种表面中以Pt(111)的表面能最低,结构最稳定.氢原子在不同M-Pt(111)双金属表面上的最稳定吸附位均为fcc穴位,其中在Ni-Pt双金属表面的吸附能最低,Co-Pt次之.表明氢原子在Ni-Pt和Co-Pt双金属表面的吸附最稳定.通过对氢原子在M-Pt(111)双金属表面吸附前后的局域态密度变化的分析,验证了氢原子吸附能计算结果的准确性.掺杂金属Ni、Co、Fe的3d-Pt(111)双金属表面在吸附氢原子后发生弛豫,第一层和第二层金属原子均不同程度地向外膨胀.此外,3d金属的掺入使得其对应的M-Pt(111)双金属表面d带中心与Pt相比更靠近费米能级,吸附氢原子能力增强,表明3d-Pt系双金属表面有可能比Pt具有更好的脱氢活性.
The adsorption behaviors of three hydrogen atoms on Pt (100), (110) and (111) surfaces were investigated by density functional theory (DFT) The most stable adsorption sites, surface energies, and atomic-layer relaxation before and after metal adsorption on (111) bimetallic (M = Al, Fe, Co, Ni, Cu and Pd) The variation of the local density of state before and after adsorption and the deviation of the center of d band from the Fermi level in the bimetallic surface were correlated with the hydrogen adsorption energies. The calculated results show that in the Pt (100), Pt (110) and Pt (111) The stable adsorption sites on the surface and hydrogen atoms are the bridge site, the short bridge site and the fcc point, respectively. The surface energy of Pt (111) is the lowest and the structure is the most stable. The most stable adsorption sites on the surface are fcc points, of which Ni-Pt bimetallic surface adsorption lowest, Co-Pt second, indicating that hydrogen atoms in the Ni-Pt and Co-Pt bimetallic surface adsorption the most stable. The accuracy of the calculation results for the hydrogen adsorption energy was verified by analyzing the variation of the local density of hydrogen atoms before and after adsorption on the M-Pt (111) bimetallic surface. The 3d-Pt (111) bimetallic surface of Ni, Co, Fe relaxes after hydrogen atoms are adsorbed, and both the first and second metal atoms expand outward to some degree.In addition, The corresponding d-band center of the M-Pt (111) bimetallic surface is closer to the Fermi level than Pt and the ability to adsorb hydrogen atoms is enhanced, indicating that the 3d-Pt bimetallic surface may have a better dehydrogenation activity than Pt .