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

Abstract

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 H2 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 300K; this species reacted at ∼300K to form CO and H2. On Co–Pt–Pt(111), methoxy was stable up to ∼350K and decomposed to form CO and H2. Overall, trends in methanol reactivity on Ni∕Pt(111) bimetallic surfaces were similar to those previously determined for ethanol and ethylene glycol.