Polycyclic Aromatic Hydrocarbons (PAHs)

Abstract

In this work, we report the structure, intermolecular forces, electronic/optical 8 properties, and stability in solution of complexes formed between polycyclic aromatic 9 hydrocarbons (PAH) and phosphorene nanoflakes by density functional theory modeling. 10 PAH molecules reach a strong affinity with phosphorene by forming well-ordered domains, 11 whose interaction strength decreases 13-21% compared to the interaction onto carbonaceous 12 surfaces, e.g., graphene. The adsorption energies are in linear relation with the NH:NC ratio 13 of PAHs, where NH and NC are the numbers of H and C atoms; consequently, the cohesive 14 energy of phosphorene-graphene heterostructures is estimated in 44 meV/atom. Energy 15 decomposition (ALMO-EDA) and electron-density-based analyses support the major role of 16 electrostatics driving forces in the interaction mechanism, which is balanced with dispersion 17 effects for larger PAHs. In addition, phosphorene-PAH complexes display outstanding 18 stability in solution under polar/non-polar solvents, which is due to the high polarity of the 19 complexes and strong overcompensation of destabilizing solvation energies with stabilizing 20 electrostatic effects. Moreover, PAHs behave as n-dopants for phosphorene, inducing small 21 bandgap opening and weak effects on the photophysical fingerprint of phosphorene. 22 Nevertheless, strong electron acceptor/donor and larger PAHs (NH:NC<0.5) lead to major 23 effects on the bandgap control, acting as active sites for orbital-controlled interactions. These 24 findings serve as a framework for further investigation of phosphorene-based materials for 25 remediation of PAH pollutants in water treatment technologies and uses of PAHs for 26 phosphorene surface passivation or bandgap engineering for sensing. 27