Effects of masking titanium with a one-atom-thick carbon layer on the adsorption of nitrogen monoxide, nitrogen dioxide, ozone, and formaldehyde

Abstract

We investigated the adsorption of each of four pollutant molecules, namely nitrogen monoxide, nitrogen dioxide, ozone, and formaldehyde, on the surface of a [0001] titanium slab, when it has adsorbed a one-atom-thick carbon layer. The tile is made of four titanium layers. Density functional theory and molecular dynamics were utilized. Atmospheric pressure and 300 K were considered. We found chemisorption of the four molecules on the [0001] titanium surface. Then, we optimized the interaction of the metal surface and a one-atom-thick carbon layer. The carbon atoms end up bound to titanium atoms on the surface. Carbon atoms' quasilinear chains are formed. The adsorption energy per carbon atom is − 2.054 eV. There is no migration of carbon atoms to the bulk. We found significant changes in the adsorption properties. The new system repels formaldehyde and nitrogen oxide molecules. In the ozone case, chemisorption of one oxygen atom on the surface is found, and the remaining oxygen molecule is repelled. In the nitrogen dioxide case, chemisorption of one oxygen atom on the surface is found too, and the leftover fraction is also repelled. These calculations were performed using GGA, and afterward, we utilized Vdw-DF2, which includes long-range correlation effects. The same results are obtained.