N_2在Co掺杂Ru(001)表面吸附的DFT研究

采用密度泛函理论与周期性平板模型相结合的方法,对N_2在Ru(001)表面top、fcc、hcp、bridge四个吸附位和Ru-Co(001)表面Ru-top、Co-top、Ru(Ru)Ru-bridge、Co(Co)Co-bridge、Ru(Co)Co-bridge、Ru(Ru)Co-bridge、Ru_2Co-hcp、RuCo_2-hcp、Ru_2Co-fcc、RuCo_2-fcc十个吸附位的14种吸附模型进行了构型优化、能量计算,得到了N_2较有利的吸附位;并对清洁表面进行能带分析,对最佳吸附位进行总态密度分析.结果表明:掺杂Co后,Ru催化剂的能带变宽,催化活性增强;N_2在Ru(001)表面的最稳定吸附位top的吸附能是-88.94 kJ·mol~(-1),在Ru-Co(001)表面的最稳定吸附位Ru-top的吸附能是-95.71 kJ·mol~(-1),而且N_2与金属表面成键,属于化学吸附.

Density Functional Theory Study of N2 Adsorption on Ru(001) Surface by doping with Cobalt

The density functional theory (DFT) and periodic slab model have been used to investigate N2 adsorption on Ru(001) and Ru-Co(001) surfaces. The adsorption energies, equilibrium geometries of N2 on four possible sites (top,fcc,hcp,and bridge) on Ru(001) surface and on ten possible sites Ru-top,Co-top,Ru(Ru)Ru-bridge,Co(Co)Co-bridge,Ru(Co)Co-bridge,Ru(Ru)Co-bridge,Ru2Co-hcp,RuCo2-hcp,Ru2Co-fcc, and RuCo2-fcc] on Ru-Co(001) surface have been predicted and compared. The relatively favorable adsorption sites have been found . Band structures of the clean Ru(001) and Ru-Co(001) surfaces and density of states analysis of the most stable sites have been discussed. The results reveal that the range of energy band for cobalt-doped Ru(001) surface have been enhanced and the activity of catalyst have been improved; the adsorption energy for N2 adsorption on the most stable sites on Ru (001) and Ru-Co(001) surfaces are -88.94 and -95.71 kJ•mol-1 , respectively. The calculated results show that there are chemical bonds between Nitrogen and Ru(001), Ru-Co(001) surface , respectively.