Functionalized Amorphous\nCarbon Materials via Reactive\nMolecular Dynamics Simulations

We derive a database of atomistic structural models of\namorphous\ncarbon materials endowed with exohedral functional groups. We start\nfrom phases previously derived using the DynReaxMas method for reactive\nmolecular dynamics simulations, which exhibit atomistic and medium-length-scale\nfeatures in excellent agreement with available experimental data.\nGiven a generic input structure/phase, we develop postprocessing simulation\nalgorithms mimicking experimental preparation protocols aimed at:\n(1) “curing” the phase to decrease the defect concentration;\n(2) automatically selecting the most reactive carbon atoms via interaction\nwith a probe molecular species, and (3) stabilizing the phase by saturating\nthe valence of carbon atoms with single-bond functional groups. Although\nwe focus on oxygen-bearing functionalities, they can be replaced with\nother monovalent groups, such as –H, –COOH, –CHO,\nso that the protocol is quite general. We finally classify reactive\nsites in terms of their location within the structural framework and\ncoordination environment (edges, tunnels, rings, aromatic carbons\nbecoming aliphatic) and try to single out descriptors that correlate\nwith tendency to functionalization.