Experimental and theoretical study of reactivity trends for methanol on Co/Pt(111) and Ni/Pt(111) bimetallic surfaces

Methanol was used as a probe molecule to examine the reforming activity of oxygenates on Ni/Pt(111) and Co/Pt(111) bimetallic surfaces, utilizing density functional theory (DFT) modeling, temperature-programed desorption, and high-resolution electron energy loss spectroscopy (HREELS). DFT results revealed a correlation between the methanol and methoxy binding energies and the surface d-band center of various Ni/Pt(111) and Co/Pt(111) bimetallic surfaces. Consistent with DFT predictions, increased production of H-2 and CO from methanol was observed on a Ni surface monolayer on Pt(111), designated as Ni-Pt-Pt(111), as compared to the subsurface monolayer Pt-Ni-Pt(111) surface. HREELS was used to verify the presence and subsequent decomposition of methoxy intermediates on Ni/Pt(111) and Co/Pt(111) bimetallic surfaces. On Ni-Pt-Pt(111) the methoxy species decomposed to a formaldehyde intermediate below 300 K; this species reacted at similar to 300 K to form CO and H-2. On Co-Pt-Pt(111), methoxy was stable up to similar to 350 K and decomposed to form CO and H-2. Overall, trends in methanol reactivity on Ni/Pt(111) bimetallic surfaces were similar to those previously determined for ethanol and ethylene glycol. (c) 2007 American Institute of Physics.