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

The advancements in electrochemical capacitors have noticed a remarkable enhancement in the performance for smart electronic device applications, which has led to the invention of novel and low-cost electroactive materials. Herein, we synthesized nanostructured Al2O3 and Al2O3-reduced graphene oxide (Al2O3-rGO) hybrid through hydrothermal and post-hydrothermal calcination processes. The synthesized materials were subject to standard characterisation processes to verify their morphological and structural details. The electrochemical performances of nanostructured Al2O3 and Al2O3- rGO hybrid were evaluated through computational and experimental analyses. Due to the superior electrical conductivity of reduced graphene oxide and the synergistic effect of both EDLC and pseudocapacitive behaviour, the Al2O3- rGO hybrid shows much improved electrochemical performance (similar to 15-fold) as compared to bare Al2O3. Further, a symmetric supercapacitor device (SSD) was designed using the Al2O3- rGO hybrid electrodes, and detailed electrochemical performance was evaluated. The fabricated Al2O3- rGO hybrid-based SSD showed 98.56% capacity retention when subjected to similar to 10,000 charge-discharge cycles. Both the systems (Al2O3 and its rGO hybrid) have been analysed extensively with the help of Density Functional Theory simulation technique to provide detailed structural and electronic properties. With the introduction of reduced graphene oxide, the available electronic states near the Fermi level are greatly enhanced, imparting a significant increment in the conductivity of the hybrid system. The lower diffusion energy barrier for electrolyte ions and higher quantum capacitance for the hybrid structure compared to pristine Al2O3 justify improvement in charge storage performance for the hybrid structure, supporting our experimental findings.

Automated summary

Advancements in electrochemical capacitors have led to the development of novel and low-cost electroactive materials, greatly enhancing the performance of smart electronic devices. In this study, nanostructured Al2O3 and Al2O3-rGO hybrid were synthesized and characterized for their morphological and structural details. The hybrid material showed significantly improved electrochemical performance due to the superior electrical conductivity of reduced graphene oxide and the synergistic effect of both EDLC and pseudocapacitive behavior. A symmetric supercapacitor device using the hybrid electrodes exhibited high capacity retention after thousands of charge-discharge cycles. Density Functional Theory simulation analysis provided further insights into the structural and electronic properties of the materials, supporting the experimental findings.