Adsorption of H2S on carbonaceous materials of different dimensionality

• H2S on carbonaceous materials is studied as a potential source of hydrogen.
• Pristine and Ti doped carbonaceous materials of different dimensionality are explored.
• H2S adsorbs weakly on (3,3) carbon nanotube and graphene but strongly and dissociatively on a carbon nanotube.
• H2S adsorbs strongly on the Ti modified materials.

The effect of the dimension of carbonaceous systems, from two to zero, on the adsorption strength of H2S is investigated by density functional theory based methods. To this end, a carbon nanocone (CNC), a (3, 3) carbon nanotube ((3, 3)-CNT), and graphene (G) are chosen as models for zero-, one- and two-dimensional systems, respectively. Pristine G and CNC have low tendency to adsorb H2S but on the (3, 3)-CNT the molecule adsorbs dissociatively and deforms the surface. The effect of doping the surface of these materials with Ti has also been investigated. The presence of Ti modifies H2S adsorption capability to the point that it is chemically adsorbed on the three decorated surfaces although H2S adsorption on Ti decorated graphene appears to be different from two other doped surfaces. Only in this case, the H2S molecule dissociates and releases hydrogen atoms which form H2 molecule. The resulting H2 molecule is physisorbed on the Ti-decorated graphene surface and the S atom adsorbs directly on the Ti atom. The density of states of pristine, Ti decorated and H2S adsorbed nanostructures demonstrate that the systems change their conductivity and magnetic properties.

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