ClO-driven degradation of graphene oxide: new insights from DFT calculations
Article
Overview
Research
Identity
Additional Document Info
View All
Overview
abstract
We present an extensive investigation using density functional theory (DFT) calculations on various model graphene oxide (GO) nanostructures interacting with ClO, aiming to understand the role of this highly oxidizing species in C—C bond breakage and the formation of significant holes on GO sheets. As an anion, the myeloperoxidase (MPO) enzyme abundantly generates hypochlorite, and its presence has been identified as the cause of degradation in carbon nanotubes of diverse sizes, morphologies, and chemical compositions, both in in vivo and in vitro samples. Notably, Kurapati et al. (Small2015, 11, 3985-3994) demonstrated efficient degradation of single GO monolayers through MPO catalysis, though the exact degradation mechanism remains unclear. In our study, we discover that breaking C—C bonds in a single graphene oxide sheet is achievable through a simple mechanism involving the dissociation of two ClO molecules that are chemically attached as nearest neighbor species but bonded to opposite sides of the GO layer (up/down configuration). Two new carbonyl oxygens appear on the surface and the Cl atoms can be transferred to the carbon layer or as physisorbed species near the GO surface. Relatively small energy barriers are associated with this molecular events. Continuing this process on neighboring sites leads to the presence of larger holes on the GO surface, accompanied by an increase in carbonyl species on the carbon network, consistent with x-ray photoelectron spectroscopy measurements. Indeed, the distribution of oxygen functionalities is found to be crucial in defining the damage pattern induced in the carbon layer. These predictions could be the root cause of the experimentally observed low stability of individual GO sheets during the MPO catalytic cycle. Lastly, we explore the possibility of achieving chlorination of GO following MPO exposure.
