Adsorption of Pd on the Cu(111) surface and its catalysis of methane partial oxidation: A density functional theory study

The single atom alloy catalysts that Pd atoms alloy on Cu(1 1 1) surface has been extensively researched for catalytic partial oxidation of methane (CH4), however the current model mainly focuses on atomic substitution. Here, a new single atom alloy configuration of a Pd atom adsorbed on Cu (1 1 1) surface is proposed (A-Pd/Cu (1 1 1)). We systematically studied the partial oxidation of methane over a doped Pd/Cu(1 1 1) (D-Pd/Cu(1 1 1)) catalyst and over a adsorbed Pd/Cu(1 1 1) (A-Pd/Cu(1 1 1)) catalyst with the help of density functional theory (DFT) simulation. The results indicate that using oxygen as oxidant can reduce the activation energy barrier of CHx oxidation than hydroxy. The partial oxidation of methane process on the D-Pd/Cu(1 1 1) catalyst (CH4 -> CH3 -> CH3O -> CH2O -> CHO -> CO) was different to that on the A-Pd/Cu(1 1 1) catalyst (CH4 -> CH3 -> CH2 -> CH -> CHO -> CO). By comparison, we believe that CO is more likely generated on the catalyst of D-Pd/Cu(1 1 1) and it shows better performance in thermodynamics and has a higher capacity for sintering resistance.