Insights into the effect of Pt doping of Cu(110)/H2O for methanol decomposition: a density functional theory study

Abstract

Density functional theory calculations with the periodic slab model are performed to investigate the mechanism of methanol decomposition with different ratios of Pt doped into Cu(110)/H₂O surfaces. Three catalyst models are constructed, denoted 9Pt–Cu(110)/H₂O, 3Pt–Cu(110)/H₂O and 1Pt–Cu(110)/H₂O. Comparing the results with those from experiments conducted on a Cu(110)/H₂O surface, the interactions between CH₃O and the constructed substrates are weakened, and the adsorption strength of CH₂O, CHO and CO is enhanced. The optimal pathway for methanol decomposition on the 9Pt–Cu(110)/H₂O surface is CH₃OH → CH₂OH → CH₂O → CHO → CO; the favorable pathway for methanol decomposition on 3Pt–Cu(110)/H₂O, 1Pt–Cu(110)/H₂O and Cu(110)/H₂O surfaces is CH₃OH → CH₃O → CH₂O → CHO → CO. Comparing the activation energies and reaction energies of each step, the Pt dopant promotes the C–H bond scission of CH₃O and the dehydrogenation of CH₂O, but slightly hinders the O–H bond breaking of CH₃OH. In general, monatomic Pt doping into the Cu(110) surface (1Pt–Cu(110)/H₂O) can result in excellent catalytic activation considering the price of Pt and the catalyst resistance to CO poisoning. Finally, linear scaling relations for the main elementary steps involved in CH₃OH decomposition on 9Pt–Cu(110)/H₂O, 3Pt–Cu(110)/H₂O and 1Pt–Cu(110)/H₂O surfaces are identified.