The adsorption of hydrogen and oxygen on magnesium oxide: The effect of γ-irradiation

Abstract

The adsorption of hydrogen and oxygen on magnesium oxide surfaces with and without the influence of continuous γ-irradiation has been investigated. The temperature range for hydrogen was 294-773 K, and for oxygen 294-973 K. In the absence of radiation little adsorption of oxygen was detected below 573 K, but above this temperature an activated process requiring an E_a of 60.6±5.0 kJ mol^-1 was obtained. At all temperatures, continuous γ-irradiation enhanced the adsorption, and a mechanism involving (e^-|□^-)_s defect centres has been proposed. Hydrogen adsorption was detected at all temperatures in the absence of radiation and an enhancement of the uptake was noted during radiation at all temperatures above 294 K.     The G^ads for oxygen decreased with increasing temperature whilst that for hydrogen increased with temperature. A mechanism for this marked difference has been proposed.