Investigations on the capacitive behaviour of hydrothermally synthesised cadmium meta niobate incorporated reduced graphene oxide hybrid nanocomposite electrode material

Reduced graphene oxide/cadmium meta niobate (RGOCN) hybrid nanocomposite was hydrothermally synthesised and subjected to structural characterization through X-ray diffraction and various microscopic analysis. Pure CN exhibited a cubical, rectangular slab like mixed morphology with average particle size ranging from 50 nm to 2 μm. Further, this work revealed that RGOCN composite showed exfoliation of graphene sheets with mixed morphology of cubes and rectangular slab. Spectral analysis enabled in understanding the various functional groups present in RGOCN. The optical band gap of prepared RGOCN composite material was estimated as 4.024 eV. The calculated remanent polarization and coercive electric field of cadmium niobate (CN) and RGOCN are P_r = 0.0151 µC cm⁻², E_c =  − 1.30 kV cm⁻¹ and P_r = 0.0685 µC cm⁻², E_c = − 2.39 kV cm⁻¹, respectively. RGOCN was developed into an electrode material and its electrochemical behaviour was evaluated by adopting the cyclic voltammetry and galvanostatic charging discharging measurements. The observed specific surface area of hybrid RGOCN showed enhanced redox current rate than the pseudo-capacitive CN. Also, hybrid RGOCN electrode furnished enhancement in specific capacitance for different scan rates and current density than CN. Specific capacitance of RGOCN was estimated to be 58.2 F g⁻¹ for very low molar H₂SO₄ electrolyte at a current density of 1 A g⁻¹. Furthermore, RGOCN coated over carbon electrode furnished cyclic stability with 98% of capacitive retention after 500 cycles at 2 A g⁻¹. The maximum energy density of 8.08 Wh kg⁻¹ with consuming high power density of 4137 W kg⁻¹ at 1 A g⁻¹ compared with few other reported materials make graphene nested CN nanocomposite stay as a significant material supporting energy storage applications.