CH_4在Fe(111)上解离的DFT研究

DFT calculation of dissociation of CH_4 on Fe(111) surface

运用广义梯度密度泛函理论方法(density functional theory,DFT),结合周期性平板模型,研究了CH4在Fe(111)面上的解离。计算结果表明,在Fe(111)面上,CH4的第一步解离是反应的决速步,其活化能垒约为1.02eV,比Ni(111)面上CH4解离的活化能低0.34eV,说明CH4在Fe(111)面上更容易解离生成C。根据计算结果,我们可以预测,把Fe加入Ni晶体中形成的面心立方的Ni-Fe合金催化剂不能抑制C的形成,这与实验结果相一致。

A density-functional theory method was adopted to systematicall y investigate the dissociation of CH4 on Fe（111） surface.The results were compared with those obtained on pure Ni（111） surface.It shows that the first step and the fourth step of CH4 dissociation both are the rate-determining st eps with the energy barrier of about 1.04 eV,which is 0.32eV lower than that on Ni（111）,indicating that C is easier to form on Fe（111） surface.Accordin g to the results,the carbon formation would not be inhibited by addition of Fe into Ni to form FCC NiFe catalyst,which is consistent with the e xperimental results.