Enhancement C–H bond activation of methane via doping Pd, Pt, Rh and Ni on Cu(1 1 1) surface: A DFT study

Density functional theory (DFT) calculations have been employed to study the adsorption and dehydrogenation mechanism of CH_x (x = 1–4) on the non-doped Cu(1 1 1) and M-Cu(1 1 1) surfaces (M = Pd, Pt, Rh and Ni). The adsorption intensity of CH₂, CH and C species were higher on M-Cu(1 1 1) surface than non-doped Cu(1 1 1) surface. The minimum energy paths for CH₄ sequential dehydrogenation were also studied, suggesting that CH₄ desorption was more favorable than the dissociation due to the weakly physical adsorption. Interestingly, it was found that CH_x dissociation was promoted in different degree on the M-Cu(1 1 1) surface both kinetically and thermodynamically, with the trend of Rh > Ni > Pt > Pd.