Adsorption of formamide on pure, Al-, N-doped, and Al/N co-doped (8, 0) single-wall carbon nanotubes: a DFT study

This study investigates the sensing capabilities of (8,0) SWCNTs in detecting formamide (HCONH2), a molecule crucial for the structure of proteins, nucleic acids, and certain anti-cancer drugs. Adsorption of HCONH2 on pristine SWCNT, Al- and N-doped SWCNT, and Al/N co-doped SWCNT was studied using dispersion-corrected density functional theory (DFT-D). Formamide was adsorbed from both oxygen and –NH2 sides, and the structures were fully optimization. The relaxed structures were applied for calculating magnetic and electronic properties like adsorption energies, band structures, and partial density of states. Most negative adsorption energy in doped structures indicates the strongest adsorption of formamide in doped structures than pristine SWCNT. The results also indicates that formamide adsorption does not change the electronic properties of pure SWCNT and N-doped SWCNT. However, it removes the band gaps of Al- and Al/N-doped SWCNT. Therefore, the modified nanotubes convert from semiconductor to metallic character which can be detected using electronic devices. Moreover, formamide adsorption induces some magnetization to Al-doped SWCNT and Al/N co-doped which can be utilized in spin transport devices. These findings suggest that Al/N co-doped and Al-doped SWCNTs are good candidates for detecting HCONH2 molecules. Graphical abstract