Adsorption of Small Gas Molecules onto Pt-Doped Single-Walled Carbon Nanotubes

The adsorption of small gaseous molecules to the metal center in Pt-doped (5,5) single-walled carbon nanotubes has been explored within density functional theory. A model system consisting of a single Pt atom residing in the middle of a carbon nanotube with capping H atoms is used for our investigation. For all gases studied, the overall process of adsorption was found to be exothermic, where the affinity strongly depended on the orientation of the molecule. By examining the density of states and molecular orbitals of these nanotube−adsorbate complexes in comparison to the bare Pt-doped nanotube, we show that the electronic structure of these materials is strongly influenced by the presence of gases. Hence, we propose an application of Pt-doped single-walled carbon nanotubes as gas sensors and hope to motivate experimental work in this field.