CO₂ and CO Capture on the ZnO Surface: A GCMC and Electronic Structure Study

The amount of polluting gases released into the atmosphere has grown drastically. Among them, it is possible to cite the release of CO₂ and CO gases on a large scale as one of the products of the complete and incomplete combustion of petroleum-derived fuels. It is worth noting that the production of energy by burning fossil fuels supplies the energy demand but causes environmental damage, and several studies have addressed the reduction. One of them is using materials with the potential to capture these gases. The experimental and theoretical studies have significant contributions that promote advances in this area. Among the materials investigated, ZnO has emerged, demonstrating the considerable potential for capturing various gases, including CO₂ and CO. This work used density functional theory (DFT) and Grand Canonical Monte Carlo Method (GCMC) to investigate the adsorption of CO₂ and CO on the surface of Zinc oxide (ZnO) to obtain adsorption isotherms and interaction energy and the interaction nature. The results suggest that CO₂ adsorption slightly changed the angle of the O-C-O to values less than 180°. For the CO, its carbon atom interacts simultaneously with Zn and O of the ZnO surface. However, CO interactions have an ionic character with a lower binding energy value than the CO₂ interaction. The energies calculated using the PM6 and DFT methods generated results compatible with the experimental values. In applications involving a mixture of these two gases, the adsorption of CO₂ should be favored, and there may be inhibition of the adsorption of CO for high CO₂ concentrations.