The adsorption of methanol on NiO x/Ni{110} : Defect-controlled dissociation

Abstract

The adsorption, desorption and dissociation of methanol on thin film nickel oxide surfaces grown on a Ni{110} substrate has been investigated using RAIRS. Two thin film oxides have been prepared at two different temperatures (300 and 570–650 K), referred to as the low-temperature (low T) and high-temperature (high T) oxides, respectively. At 130 K, methanol adsorbs molecularly on the regular NiO terraces. Molecular desorption occurs at around 250 K indicating weak chemisorption. However, a small concentration of a more strongly bound methoxy species is observed on the surface of the high T oxide at temperatures in excess of 350 K. In direct contrast, no dissociation to methoxy is observed to occur for methanol adsorption on the low T oxide. In an analogous manner to the dissociation of the water molecule on nickel oxide surfaces, it appears that non-lattice oxygen facilitates abstraction of the hydroxyl hydrogen resulting in the formation of adsorbed methoxy.