Three dimensional NiS2–Ni(OH)2/CNT nanostructured assembly for supercapacitor and oxygen evolution reaction

Abstract

In this work, three-dimensional hetero-nanostructures comprising nickel sulfide/nickel hydroxide and multiwalled carbon nanotubes have been synthesized using hydrothermal method for energy conversion and storage application. As-prepared NiS2–Ni(OH)2/CNT composite shows excellent storage properties with a specific capacitance of 1250 F/g with pseudocapacitive behavior. Interestingly, NiS2–Ni(OH)2/10% CNT electrode exhibited better cycling stability with 80% retention of specific capacitance after 3000 cycles at a current density of 5 A/g. Further, when employed as oxygen evolution reaction (OER) catalyst, NiS2–Ni(OH)2/10%CNT composite electrode exhibits an OER onset potential of 1.45 V vs reversible hydrogen electrode (RHE) and it can catalyze OER efficiently with the overpotential of 290 mV to generate 10 mA/cm2 current density (with a lower Tafel slope 110 mV/decade) in an alkaline solution. The stability studies also confirm an excellent performance of NiS2–Ni(OH)2/CNT even after 2000 cycles without obvious degradation, due to the formation of three-dimensional network of layered sulphide and one-dimensional CNTs that plays a main role in the energy conversion and storage.