On the adsorption of arsenic on single-walled carbon nanotube and Fe-doped single-walled carbon nanotube: a quantum chemical study

Due to mounting environmental and public health concerns about the toxicity of Arsenic (As) contamination, there is a strong drive to develop ultrasensitive sensors and adsorbent material for As. Herein, we present results from density functional theory, the fundamental operating principle of the interaction of SWCNT with atomic As and Arsenous acid (H3AsO3), and its corresponding electronic-optical response. The calculations indicate that atomic As can strongly interact with SWCNT with significant induced structural deformation on the SWCNT's C-C bond. This bonding modifies the prototype SWCNT's intrinsic electronic structure and optical absorption spectra. Hence, SWCNT is indeed a competitive adsorbent and sensing material for atomic As. On the other hand, H3AsO3 interacts weakly with the SWCNT, with no significant modification observed in the SWCNT's atomic configuration, electronic structure, and optical absorption spectra. The interaction and sensitivity with H3AsO3 significantly improved after doping the SWCNT with Fe. Furthermore, the changes in the band structure patterns and optical absorption spectra of Fe-doped SWCNT are also prominent upon exposure to H3AsO3. The results presented here provide fundamental insights into the interaction of SWCNT and As, which serve as a reference for fabricating SWCNT-based adsorbent and sensing platforms of heavy metals. The findings further give insights into the chemical sensing performance of metal-doped SWCNT.