Effect of epoxy groups and defects on the interfacial properties of RGO/Ti composites using the first principles simulation

To develop high-performance titanium/graphene oxide/titanium (Ti/GO/Ti) matrix composites, the effects of the number of epoxy groups and the type of defects on the interfacial properties of the composite models were investigated. The increase of epoxy groups on GO resulted in the enhancement of the interfacial adhesion work but the decrease of the interfacial energy between GO and Ti groups, which was conducive to enhancing interfacial bonding strength. Both single vacancy defects and topological defects favor the interfacial bonding between GO and Ti groups at one and two epoxy groups, and double vacancy defects have a negative effect when there are two epoxy groups. The interaction between C and Ti atoms is strongest at double vacancy defects (single vacancy defects), followed by topological defects, and weakest atoms at single vacancy defects (double vacancy defects) when one (two) epoxy groups are present. The defects cause the integrity of the C atoms in GO to be significantly broken, creating stronger interactions at the interface. The peaks of the d orbitals of Ti atoms in the Ti/GO2/Ti composite model under the three types of defects are reduced compared to pure Ti/GO2/Ti but increased compared to pure Ti/GO1/Ti.