The adsorption of the amino acid glycine (NH2CH2COOH) on (3,3) armchair carbon nanotubes has been investigated through calculations based on density functional theory (DFT). A comparison of the adsorption energies for four adsorption models is presented, showing glycine in its zwitterionic form is generally bound stronger to the nanotube sidewall as compared to its nonionic counterparts. Adsorption through the carboxylate group of the glycine zwitterion exhibited the strongest interaction, favourably adsorbing with an adsorption energy of 0.53 eV. Further investigations on the adsorption of glycine on graphite sheets have showed weaker interactions as compared to adsorption onto the nanotube surface, suggesting a decrease in glycine adsorption strength with increasing nanotube diameter.
Bibliographical noteFunding Information:
This work is partly supported by: a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT); the 21st Century Center of Excellence (COE) Program “Core Research and Advance Education Center for Materials Science and Nano-Engineering” supported by the Japan Society for the Promotion of Science (JSPS); and the New Energy and Industrial Technology Development Organization's (NEDO) Materials and Nanotechnology program. Some of the calculations were done using the facilities of the Information Technology Based Laboratories Project of the Japan Atomic Energy Research Institute (ITBL, JAERI), and the High Performance Computing Laboratory of De La Salle University, Manila.
- Amino acids
- First principles calculations