H_2在Al_(12)X(X=Al,Ni,Cu)团簇表面解离吸附的第一性原理研究

The first-principles study of the dissociative adsorption of H_2 on the surfaces of Al_(12)X( X = Al,Ni,Cu) clusters

以Ni和Cu原子中心替换的二十面体Al_(12)X(X=Ni、Cu)团簇为基体、采用密度泛函理论系统计算研究了H原子及H_2分子在团簇表面的吸附,并对比了纯Al_(13)团簇对H及H2的吸附,结果表明:相对于纯Al_(13)中H原子的桥位吸附、掺杂团簇Al_(12)X(X=Ni、Cu)中H原子均吸附于团簇顶位;无论是吸附H原子还是H_2分子,Al_(12)Ni的几何结构均发生大的畸变;相较H_2在纯Al_(13)团簇表面的解离吸附,H_2在掺杂团簇Al_(12)X(X=Ni、Cu)表面的解离反应过程中反应能均增大、势垒均降低,这表明掺杂团簇Al_(12)X(X=Ni、Cu)相较纯Al_(13)团簇更有利于H_2解离吸附的发生.

Based on the icosahedral Al12 X （X = Ni, Cu） clusters with the doped atoms in the center, the adsorptions of H atom and H2 molecule on the surfaces of these clusters are systematically investigated by using the density - functional theory calculations, and the obtained results are compared with those of the adsorptions of H and H2 on the pure Al13 cluster. Our results show that： Compared to the bridge site of the H atom on pure Al13, H adsorbs on the top site of each of the Al13X （X = Ni.Cu） clusters; The geometric structure of Al12Ni is greatly distorted in the adsorption of either a hydrogen atom or a H2 molecule. For the comparison of the dissocia- tive adsorption of H2 on the surface of pure Al13 cluster, the reaction energies all increase and the potential barri- ers all decrease in the dissociation reaction processes of H2 on the surfaces of the doped Al12 X （ X = Ni, Cu） clusters, which implies that the doped Al12X （X = Ni, Cu） clusters are more favorable for the occurrence of the dissociative adsorption of H2 than the pure Al13 cluster.