Adsorption and Decomposition of CO2 on Γ-Al2o3(100): First-principles Investigation

The adsorption and dissociation of CO2 on perfect and oxygen-deficient gamma-Al2O3(1 0 0) is comparatively studied using first-principles calculations. CO2 molecules are found to physically absorb at perfect gamma-Al2O3(1 0 0) with a linear configuration without the tendency to decompose. By contrast, the presence of oxygen vacancies at the gamma-Al2O3(1 0 0) surface results in direct CO2 decomposition at the oxygen vacancy sites or the CO2 adsorption at the Al site adjacent to the oxygen vacancy, followed by the CO2 molecular rotation to the oxygen vacancy site and subsequent decomposition. The charge transfer between adsorbed CO2 and the gamma-Al2O3(1 0 0) surface is further analyzed to understand the oxygen deficiency effect on CO2 adsorption and decomposition. These results demonstrate the promoting effect of oxygen vacancies of the oxide catalysts on CO2 activation, which have practical importance in catalytic CO2 conversion to value-added chemicals and controlling the oxidation of alumina-forming alloys in CO2 containing atmospheres.