纳米金催化NO+CO反应机理的密度泛函理论研究(英文)

DFT Studies of NO+CO Reaction Mechanism on Nanopartical Gold

采用密度泛函理论对NO+CO反应机理在Au(111)面上的反应历程进行详细讨论。通过对表面吸附物种(N、O、NO、CO、N_2、N_2O、CO_2)的吸附行为进行研究,得到最佳活性吸附中心。对三种机理中的基元反应的活化能进行计算分析,结果发现由于NO在Au(111)面上直接分解为N和O需要很高的能垒(599.4 kJ·mol^(-1)),NO+CO反应按照直接分解机理的可能性很小,按照二聚体机理的可能性更大。最佳反应途径是2NO→(NO)2→N2O+O→N2+2O,其中通过O端吸附在Au(111)面上的二聚体(NO)_2是不可避免的中问体。该反应的决速步骤是N_2O~*→N_2~*+O~*,活化能为49.5 kJ·mol^(-1)。

The mechanism of NO reduction by CO catalyzed on the Au(111) surface was elucidated by first-principle density-functional theory(DFT).All the pertinent species(N,O,NO,CO,N_2,N_2O,CO_2,(NO)_2) were calculated to obtain their preferred adsorption sites.Three possible reaction pathways of the NO+CO reaction were characterized and the reaction potential energy surface was computed.The calculation results show that the NO direct dissociation is unlikely because of its high barrier(599.4kJ·mol^(-1)).The dimer mechanism for N_2 formation on the Au(111) surface is very favorable.The(NO)_2 which is absorbed through two O atoms was found to be a necessary intermediate for the formation of Nj,and the calculated barrier for the rate-determining step N_2O*→N_2*+0* along the most energetically favorable pathway is only 49.5 kJ·mol^(-1).Therefore,the most feasible reaction pathway is 2NO→(NO)_2→N_2O+O→N_2-2O.