Synergistic effect of Fe (III) doping and MWCNTs integration on the electrochemical performance of nickel sulfide nanoparticles for hybrid supercapacitor applications

In this report, Iron (Fe) doped nickel sulfide (NiS) nanoparticles integrated with multi-walled carbon nanotubes (MWCNTs) have been prepared by hydrothermal and ultrasonication approach. X-rays studies of synthesized samples showed the existence of single-phase hexagonal Fe-NiS along MWCNTs with crystallite size of 13.19 nm. SEM images indicated spherical Fe-NiS particles encapsulated by long and thin thread like MWCNTs. Fe-NiS@MWCNTs was drop casted on nickel foam (NF) for the supercapacitor application. Fe-NiS@MWCNTs/ NF offered a specific capacity of 662C g-1 at 5 mV s-1 with excellent cyclic stability. Fe-NiS@MWCNTs/NF maintained 70.2% of initial specific capacity at a high scan rate of 100 mV s-1. For impedance studies, a small equivalent series resistance (ESR = 2.30 & omega;) and charge transfer resistance (RCT = 3.12 & omega;) were observed for Fe-NiS@MWCNTs/NF. The superior electrochemical performance of Fe-NiS@MWCNTs/NF can be accredited to the large surface area and intervened network of Fe-NiS@MWCNTs. Pseudocapacitive Fe-NiS and highly conductive MWCNTs generate synergistic effects that ultimately boost up the specific capacity of Fe-NiS@MWCNTs/NF electrode. The excellent electrochemical performance of proposes Fe-NiS@MWCNTs/NF as effective electroactive material for supercapacitor applications.