Modeling Adsorption of CO 2 in Rutile Metallic Oxide Surfaces: Implications in CO 2 Catalysis.

CO 2 is the most abundant greenhouse gas, and for this reason, it is the main target for finding solutions to climatic change. A strategy of environmental remediation is the transformation of CO 2 to an aggregated value product to generate a carbon-neutral cycle. CO 2 reduction is a great challenge because of the large C=O dissociation energy, ~179 kcal/mol. Heterogeneous photocatalysis is a strategy to address this issue, where the adsorption process is the fundamental step. The focus of this work is the role of adsorption in CO 2 reduction by means of modeling the CO 2 adsorption in rutile metallic oxides (TiO 2 , GeO 2 , SnO 2, IrO 2 and PbO 2 ) using Density Functional Theory (DFT) and periodic DFT methods. The comparison of adsorption on different metal oxides forming the same type of crystal structure allowed us to observe the influence of the metal in the adsorption process. In the same way, we performed a comparison of the adsorption capability between two different surface planes, (001) and (110). Two CO 2 configurations were observed, linear and folded: the folded conformations were observed in TiO 2 , GeO 2 and SnO 2 , while the linear conformations were present in IrO 2 and PbO 2 . The largest adsorption efficiency was displayed by the (001) surface planes. The CO 2 linear and folded configurations were related to the interaction of the oxygen on the metallic surface with the adsorbate carbon, and the linear conformations were associated with the physisorption and folded configurations with chemisorption. TiO 2 was the material with the best performance for CO 2 interactions during the adsorption.