A DFT theoretical study of CH4 dissociation on gold-alloyed Ni(111) surface

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).