Abstracts Book - IMRC 2018

• SA3-O009
TUNING THE ADSORPTION ENERGY OF ORGANIC MOLECULES ON
TWISTED-BILAYER GRAPHENE
Francisco Hidalgo 1 , Alberto Rubio 1 , Cecilia Noguez 2
1 Universidad Autónoma Metropolitana, Ciencias Básicas, Mexico. 2 Universidad Nacional
Autónoma de México, Instituto de Física, Mexico.
Graphene has been proposed for many technological applications, including
catalysis and molecular sensor. However, many of these potential applications
are not easy to achieve using pristine graphene. For instance, theoretical groups
have studied the adsorption of cysteine (a chiral essential amino acid) on
intrinsic graphene through all its functional groups (deprotonated thiol,
deprotonated amino and carbonyl), concluding that molecules are not adsorbed
unless graphene is doped with metallic atoms, like gold or platinum. Other
theoretical groups have studied adsorption of pyridine (an heterocyclic organic
compound) on graphene observing small adsorption energies, which increase
when graphene is doped with boron.
In this work, using first-principles calculations we study the adsorption energies
of pyridine and metanethiol molecules on pristine monolayer and bilayer
graphene. Exploring top, bridge and hole sites on one graphene layer, our
results show that while the methylthiol molecules (deprotonated methanethiol)
are not adsorbed in agreement with theoretical results, the methanethiol is
adsorbed with energies larger than kBT at room temperatures. Testing different
molecules orientations, it is found that pyridine can be adsorbed with
adsorption energy larger when nitrogen atom is near to graphene, in agreement
with other theoretical calculations.
On the other hand, in bilayer graphene in A-B stacking, our results show that the
adsorption energies of both molecules increase compared with monolayer
graphene. Using different relative orientation of bilayer graphene, which
generates inequivalent adsorption sites on chiral bilayer graphene defined by
Moirès pattern, the adsorption energies are different compared with monolayer
graphene. These results suggest that the adsorption process can be tuned by
just adjusting the relative orientation between monolayers, giving the possibility
to increase or decrease the adsorption energy of molecules opening potential
applications in molecular sensors.