Adsorption of oxygen on high area nickel oxide. Part 2.—Dark and photo adsorption

Abstract

The reaction of oxygen with the surface of high area nickel oxide has been studied from –195 to 200°C. The dark adsorption is minimal in the vicinity of room temperature and changes in character over the temperature range. At low temperatures, a fast reversible adsorption predominates, while, at the temperatures above room temperature, a slow irreversible adsorption is the major contributor. Illumination of the oxide can lead to both adsorption and desorption depending on the conditions. The effects seem to be independent of wavelength in the visible region and are associated with charge transfer processes in the oxygenated oxide surface. At high intensities of illumination it was possible to decompose the oxide at temperatures of 120°C and above.