The nitric acid adsorption effects on electronic structure and magnetic properties of 3D nanographene-based nanoporous system

Abstract

Nanographene inherits unprecedented electronic and magnetic properties from graphene due to its electronic feature from massless Dirac Fermion. In addition, around the zigzag-shaped edges of nanographene sheet, a nonbonding π-electron state called edge state is generated and located at the Dirac point where the bonding πand antibonding π*-band contacts. The edge state gives a localized spin, which results in unconventional nanomagnetic features and chemical activity to the nanographene sheets. Activated carbon fiber (ACFs) is an ideal candidate to access the magnetism of nanographene experimentally, which features a disordered flexible 3D network of nanographite domains, assembled by loose stacking of 3 to 4 nanographene sheets with a mean in-plane size of 2 to 3 nm. Besides, a large amount of nanosized interstitial spaces (nanopores) are distributed between the nanographite domains. The presence of nanopores accommodates large amounts of guest molecules, where the host– guest interaction plays an important role in modifying the electronic and magnetic properties of not only the host nanographite but also the guest species. In addition, many oxygen-containing functional groups, most of which are hydrophilic, are bonded to the nanographene edges, such as carboxyl, carbonyl and phenol groups. In view of magnetism, the research in this thesis focuses on the interaction between nanographene and nitric acid with strong electronaccepting nature. Some important phenomenon is observed, such as the charge transfer interaction between host and guest, the decomposition of HNO3 molecules, and the behavior of decomposed magnetic species in the nanopores and their interactions with edge-state spins.