Reactivity of molecular oxygen: conversion of methanol to formate at low temperatures on Pt(1 1 1)

The oxidation of methanol by molecular oxygen on a Pt(1 1 1) surface has been investigated by infrared reflection absorption spectroscopy and X-ray photoelectron spectroscopy. Formate is produced when the surface co-adsorbed with molecular oxygen and methanol is annealed to 70 K; the temperature is far much lower than the dissociation temperature of molecular oxygen on a clean Pt(1 1 1) surface. The attractive interaction between the co-adsorbates is postulated to lower a dissociation barrier of molecular oxygen. When a methanol-precovered Pt(1 1 1) surface is exposed to O2, the sticking probability of O2 decreases with increase of surface temperature and the major product of methanol oxidation is changed from formate to CO.