Effective assembling of nickel oxide-reduced graphene oxide heterostructures for ultrahigh capacity supercapattery

Developing new materials to facilitate sustainable and renewable energy storage is the most sought research frontier of the current era. In this regard, supercapacitors have drawn huge research attention in developing efficient electroactive materials. Herein, a nickel oxide/reduced graphene oxide (NiO-rGO) composite has been synthesized using the facile precipitation-aging-calcination and ultrasonication technique for energy storage applications. Due to the composite's enhanced surface area and the synergistic effect of redox-active NiO and highly conductive rGO, the resulting heterostructure exhibits excellent performance as a supercapattery. The electrochemical investigations show that the designed NiO-rGO heterostructure exhibits battery-type electrode features with an ultrahigh specific capacity of 850 Cg-1 at 1 Ag-1 current density with 91 % capacity retention even after 5000 charge-discharge cycles. The efficacy of this composite has also been tested in a symmetrical device assembly (NiO-rGO//NiO-rGO), which shows a very high maximum energy density (56.6 Wh.kg−1) and power density (9.65 kW kg−1) with excellent performance retention for 10000 charge/discharge cycles. Further, the experimental charge storage outcomes of the materials have also been supported by calculating the energetics of OH* adsorption using DFT. This work provides a facile approach to maximize the synergistic interactions within metal oxides-rGO-based 3D/2D heterostructures to derive improved electrochemical features. Moreover, it also offers experimental and theoretical insights into designing efficient and cost-effective materials for energy storage.