Structural transformations and enhanced electrochemical performance of Co doped NiS2 nanosheets for supercapacitor applications

Doping and morphology tailoring in metal sulfides up to nanoscale plays a vital role for better performance in various applications. Herein hydrothermally synthesized Co-doped nickel sulfide (NiS2) nanostructures have been transformed from nano-rods to nano-sheets up to optimal doping concentration of 3 %. The phase changes, morphological modifications and elemental investigations have been analyzed by SEM, TEM, HRTEM, SAED, EDS, XRD and FTIR. The morphology transitions revealed that NiCo3S exhibited sophisticated morphology of flower like structures formed by nano-sheet patterns. NiCo3S electrode possesses an auspicious capacitance of 1242 Fg_1 at 1 Ag_1 within potential window range of 0.1-0.8 V. In accordance with GCD study, CV and EIS study confirmed that NiCo3S is more electroactive and less resistive showing excellent stability up to 92 % after 5000 cycles. The power law (b = 0.71) showed the capacitive nature of the NiCo3S. The capacitive and diffusive behavior calculated by Dunn's relationship confirmed the pseudocapacitive charge storage behavior of NiCo3S electrode making this a potential candidate for electrochemical applications.