A DFT theoretical study of CH_4 dissociation on gold-alloyed Ni(111)surface

摘要

A density-functional theory(DFT)method has been conducted to systematically investigate the adsorption of CHx(x=0～4)as well as the dissociation of CHx(x=1～4)on(111)facets of gold-alloyed Ni surface.The results have been compared with those obtained on pure Ni(111)surface.It shows that the adsorption energies of CHx(x=1～3)are lower,and the reaction barriers of CH4 dissociation are higher in the first and the fourth steps on gold-alloyed Ni(111)compared with those on pure Ni(111).In particular,the rate-determining step for CH4 dissociation is considered as the first step of dehydrogenation on gold-alloyed Ni(111),while it is the fourth step of dehydrogenation on pure Ni(111).Furthermore,the activation barrier in rate-determining step is higher by 0.41 eV on gold-alloyed Ni(111)than that on pure Ni(111).From above results,it can be concluded that carbon is not easy to form on gold-alloyed Ni(111)compared with that on pure Ni(111).