Enantiomeric Adsorption of Alanine on Twisted Bilayer Graphene

Atomic layered materials have emerged as alternative systems to induce structural chirality and specific handedness. Motivated by experimental evidence of intrinsic chirality in twisted bilayer graphene (TBG), we studied the enantiomeric recognition properties of TBG in the molecular adsorption of alanine. This work studies the adsorption energies, charge densities, and electronic properties of TBG interacting with the chiral molecule through first-principles calculations. We consider the handedness (l- or r-handed) of both the molecule and TBG, as well as several adsorption sites and stacking symmetries. The magnitude of the adsorption energies is more significant than room temperature and unaffected by the stacking symmetry. We find evidence of favorable adsorption of one enantiomer over the other that can be improved via the molecule orientation on the TBG.