Structural and electronic properties of CO molecule adsorbed on the TiO2 supported Au overlayers: Insights from density functional theory computations

We have examined the adsorption behaviors of carbon monoxide (CO) molecule on TiO2 anatase supported Au overlayers. The results of density functional theory (DFT) calculations were used in order to gain insights into the effects of the adsorption of CO molecules on the considered hybrid nanostructures. We have investigated different adsorption geometries of CO over the nanoparticles. CO molecule is preferentially adsorbed on the surface of Au atoms with significant adsorption energies. It was found that the CO molecule moves preferentially towards the Au atoms when it was positioned at the top Au sites of the nanoparticle. Here, we have focused on the adsorption of CO on the studied system, and the major point is that the charge is transferred from the CO molecule to the nanoparticle. The results suggest that the oxygen atom has a little mutual interaction with the surface Au atoms. We have summarized the results of density functional theory calculations including adsorption energies, Mulliken charge analysis and electronic density of states. Charge analysis based on Mulliken charges reveals a substantial charge transfer from the CO molecule to the TiO2 supported Au overlayers. With the inclusion of van der Waals (vdW) interactions, the results show an increase in the adsorption energy values. TiO2 supported Au overlayers have strong sensing capability for the detection of CO molecules, indicating the higher adsorption ability of these modified nanostructures. The goal of this study was to report on results that provide new insights, or significantly expand our understanding of the structural and electronic properties of novel TiO2 supported Au overlayers for chemical sensing of CO molecules.