Graphene oxide in ceramic-based layered structure: Nanosheet optimization

Abstract

Using graphene oxide (GO) in ceramics can improve their performance on the molecular level. In this article, density functional theory was used to gain a better understanding of electron distribution in the composite consisting of GO inside a ceramic layered structure and its direct relation with the possible chemical bonds and bonding energy interactions. Moreover, with molecular dynamics calculations, the structure of calcium silicate hydrate (CSH) was considered as a ceramic perimeter and investigated to assess GO role. Extracted results revealed the calcium atoms in the CSH structure to be the most important species in the interaction between the CSH structure and GO. The aforementioned calcium ions have a high desire for electron, thus they are drawn to a distance from oxygen atoms residing on the functional groups to share their electron. With respect to this behavior and other factors, including the wrinkling phenomenon, an optimization study was conducted on the type, location and weight ratio of the concerned functional groups as well as the dimensions of the graphene oxide plane. Our findings expressed the complexity of GO behavior in ceramic composites as a function of several parameters. Here, results indicated that GO preserves its reinforcing quality under different scenarios concerning the combination of functional groups, their location and the optimal L/W ratio of the sheet. Best performance was achieved when hydroxyl, carboxyl and epoxy groups were presented on the surface and the edges of the GO platelet simultaneously. In this case, Young's modulus for the composite grows approximately 29%, which is not only a result of sustained mechanical properties of the GO itself, but also a product of powerful bonding between GO and CSH structures. The outcomes of this study could pave the way for applications of selectively functionalized graphene for efficient reinforcing of the GO-ceramics nanocomposites.