Cupric oxide decked few-layered graphene: Synthesis and dielectric behaviour

Insulator-conductor composites are touted as excellent materials for charge storage capacitor applications. Cupric oxide (CuO) decked few-layered graphene (FLG) can be one such composite. Understanding the dielectric behaviour of CuO-graphene system, which is anticipated to be intricate, is definitely an attention-grabbing one. Here, CuO decked FLG composite is synthesized using molecular level mixing. Samples with different amounts of FLG (low and high amount FLG containing samples are named as CuO-0.1G and CuO-0.2G, respectively) are prepared. At 1 kHz, dielectric permittivity (ε1) values of CuO-0.1G (ε1 = 318) and CuO-0.2G (ε1 = 667) are ∼1.1 and ∼2.3 times greater, respectively than that of CuO (ε1 = 289). Increase in ε1 is ascribed to the formation of continuous conductive pathway between CuO decked FLG sheets. AC conductivity (σ) of CuO-0.1G and CuO-0.2G samples is found to increase with applied frequency and follows Jonscher's power law. Experimental data pertaining to AC conductivity could be easily fitted to quantum mechanical tunnelling model. The fitting results suggest electron hopping mechanism as the cause for enhanced AC conductivity. This work gives a great motivation to develop composite materials (with conducting and insulating constituents) whose dielectric behaviour can be controlled by mechanisms occurring at atomistic scale.