Experimental and computational investigation on the charge storage performance of a novel Al2O3 -grpahene hybrid electrode

The advancements in electrochemical capacitors have noticed a remarkable enhancement in the electrochemical performance for smart electronic device applications, which has led to the invention of novel and low-cost electroactive material. Herein, we synthesized nanostructured Al 2 O 3 and Al 2 O 3 -grpahene hybrid, through hydrothermal and post-hydrothermal calcination process. The synthesized materials have been subject to both morphological (FE-SEM, HR-TEM) and structural (XRD and XPS) characterisations. The electrochemical performances of nanostructured Al 2 O 3 and Al 2 O 3 -grpahene hybrid were evaluated through computational and experimental analyses. Al 2 O 3 -grpahene hybrid shows much improved electrochemical performance, as compared to bare Al 2 O 3 . Further, a symmetric supercapacitor device (SSD) was designed using the Al 2 O 3 -grpahene hybrid electrodes, which showed 98.56% capacity retention, even after ~ 10,000 charge-discharge cycles. Both, Al 2 O 3 and its graphene hybrid, have been analysed extensively with the help of Density Functional Theory, to provide detailed structural and electronic properties. With the introduction of graphene, the available electronic states, near the Fermi level, are greatly enhanced, imparting a significant increment in the conductivity of the hybrid system. Lower diffusion energy barrier for electrolyte ions and higher quantum capacitance for the hybrid structure compared to pristine Al 2 O 3 justify improvement in charge storage performance for the hybrid structure supporting our experimental findings.