H_2在催化剂上的吸附行为

Adsorption Behavior of H_2 on Catalyst

研究了氢气在金属体Ni(111)表面的top,bridge,hcp,fcc这4个不同位置吸附能以及4个吸附位中H原子距离下层Ni原子层的垂直距离,可知hcp和fcc这2种空洞位的吸附要稳定些,bridge吸附位是非常不稳定的,容易走向hcp位吸附.各吸附位的吸附能分别是Ead-top=-11.622 kJ.mol-1,Ead-bridge=-12.036 kJ.mol-1,Ead-hcp=-12.047kJ.mol-1,Ead-fcc=-12.078kJ.mol-1,表明H2在表面Ni(111)的4种吸附属于化学吸附.表面Pt(111),Rh(111),Ru(111)对具有H2相似的吸附行为有待进一步的研究.

The adsorption behaviors of H2 at the positions of top, bridge, HCP, and FCC on the N1 （ 111 ） surface are compared and the respetive vertical distanees between the atom H and the atomic layer Ni are studied. The adsorption behavior at HCP and FCC is stable,while that at bridge adsorption position is not very stable,which is easy to shift to HCP bit adsorption. The adsorption energy at the four different posi- tions was calculatedand obtained as ： Ead-top=-11.622kJ·mol-1 ,Ead-bridge Ead-bridge=-12.036kJ·mol-1 ,Ead-hcp=-12.047kJ·mol-1,Ead-fce=-12.078kJ·mol-1. The results indicate that four kinds of adsorption of Hz on surface Ni（lll） belong to chemical adsorption. The adsorption behavior of H2 on surface Pt（111）, Rh（111） and Rh（111） need further research.