Super Dielectric Materials of Two-Dimensional TiO₂ or Ca₂Nb₃O₁₀ Nanosheet Hybrids with Reduced Graphene Oxide

High dielectric constants (e_r) were observed in two-dimensional composites obtained from stacking of reduced graphene oxide (RGO) with Ca₂Nb₃O₁₀ and with TiO₂ nanosheets. The relative dielectric permittivity values of the composites were found to be higher than 10⁵, an amazingly high value compared to that of similar GO composites and other common dielectric materials. As a consequence, we considered application of the hybrids as super dielectric materials in high capacitance supercapacitors. The route to high capacitance involves the variation of oxygen vacancies within the surface and in the closest bulk interior of the hybrids. The effective charges generated throughout the metal oxide and carbon-oxygen polar bonding systems within the graphene skeleton appear to highly influence dielectric polarization. Moreover, the replenishment of oxygen vacancies at the RGO and metal oxide interface also contributes to polarizability.