An experimental and computational study of enhanced charge storage capacity of chemical vapor deposited Ni3S2-reduced graphene oxide hybrids

Abstract

In the present approach, we have successfully synthesized wormlike Ni3S2 and Ni3S2-RGO hybrids on nickel (Ni) foam by a facile and highly reproducible one-step chemical vapor deposition (CVD) method. We have demonstrated that Ni3S2 and Ni3S2-RGO hybrids can be grown directly on the current collector of energy storage devices without using any binder, which may lead to serve industry for large-scale production of the material. We have studied the pseudocapacitive energy storage performance of the CVD grown Ni3S2 and its hybrids with variable concentration of RGO. The Ni3S2-RGO hybrid with 0.5 mg GO showed a maximum areal specific capacitance of 1.4 F·cm−2 at a current density of 1 mA·cm−2 (approximately 1124 Fg−1 at a current density of 1 Ag−1). The enhanced supercapacitive performance of Ni3S2-RGO predominantly due to its high surface area and high conductivity as compared to bare Ni3S2. The electrochemical impedance spectroscopic analysis revealed Ni3S2-RGO possess enhanced charge-transfer characteristics as compared to bare Ni3S2. Furthermore, Density Functional Theory (DFT) simulations infer the strong hybridization between C p orbital and Ni d orbital lead to enhanced electrochemical property and Density of States (DOS) is crucially responsible for the improved charge storage performance of Ni3S2-RGO hybrids.