Valine adsorption on pristine and N-doped graphenes: DFT, AIM, and IGM study

Deep insight into interactions of various biomolecules with nanomaterials is very important to design novel materials for different applications. The present work studies physical adsorption of valine, an amino acid, on the surfaces of graphene and N-doped graphenes using density functional theory (DFT). Atoms-in-molecules (AIM) and independent gradient model (IGM) analyses have been implemented to reveal the features of interactions in studied complexes. The SAPT0 method has been used to decompose total interaction energy into constituents, which allows one to carry out the complete analysis of the valine/adsorbent interactions. Dispersion forces have been found to play major roles in attractive interactions for the considered complexes. They are followed by electrostatic components. Studies of N-doping effects reveal that valine binds more strongly to the N-doped graphene surfaces in comparison with pristine graphene. The total interaction energy reaches?0.82 eV, which is ?65% larger than that for pristine graphene. Our results demonstrate that N-doped graphenes with the large interaction energy would be of importance for technical realization of the targeted delivery of valine.