Hierarchical nanostructures of nitrogen-doped molybdenum sulphide for supercapacitors

Abstract

The specific capacitance values describe the effect of urea concentration for nitrogen-doped molybdenum sulphide.

Freestanding 1T‐MnxMo1–xS2–ySey and MoFe2S4–zSez Ultrathin Nanosheet‐Structured Electrodes for Highly Efficient Flexible Solid‐State Asymmetric Supercapacitors

“…Different precursor salts were mixed in desired proportions with a clean carbon cloth submerged into the as‐prepared solution, and a hydrothermal reaction was carried out at 180° for 14 h ( Scheme ; details are provided in the Experimental Section). [ 8,15,18,24 ] In order to achieve the ultrathin nanosheet structure of Mn x Mo 1− x S 2− y Se y with an enriched 1T phase, we carried out a series of reactions. As per the literature, 10% Mn doping is optimal for the significant improvement in the optical and electrochemical performance of the bare MoS 2 .…”

“…[ 19,20 ] Moreover, as it is large in size, Se can also significantly increase the interlayer spacing of MoS 2 . [ 16–20 ] Therefore, we can conclude from the discussion so far that the strategy of co‐doping of metal and nonmetal on MoS 2 holds a high potential for significant improvement in the energy‐storage characteristics. Likewise, although the Fe 2 S 4 has been investigated as the negative electrode material for the supercapacitor, its electrochemical performance remains limited due to its moderate rate capability, poor cycling stability, and low specific capacity.…”

“…With this, a significant enhancement in the charge‐transfer kinetics is expected in these doped structures in comparison to the pristine MoS 2 . [ 16–18 ] Among the various nonmetals, theoretical studies have predicted that chemical doping of selenium (Se) on MoS 2 is thermodynamically favorable and can significantly alter the electronic structure, especially the band gap, which is an important factor for the improvement of the energy storage and catalytic performance of MoS 2 . [ 19,20 ] Moreover, as it is large in size, Se can also significantly increase the interlayer spacing of MoS 2 .…”

“…[ 1–13 ] Various nanostructures of MoS 2 or Fe 3 S 4 have been synthesized and reported to date, such as nanosheets, nanorods, nanoparticles, or nanowires. [ 6–9,14–18,21–26 ] Unfortunately, most of them, with high surface area and porosity, are synthesized in powdered form, which requires binders and conductive materials as additives for use as electrodes in supercapacitors. The additional components increase the equivalent series resistance (ESR), leading to mediocre performances of the electrode.…”

“…Freestanding electrodes, in which materials are grown directly on the current‐collecting substrate, can resolve the issues related to the shortfalls caused by such external additives. [ 12–23 ] In the present study, carbon cloth (CC) is chosen as current collecting substrate because of its super flexibility, high conductivity, excellent mechanical strength, high porosity, high corrosion resistivity, light weight, and ease of comprehensive commercialization. Typical metallic substrates like copper or aluminum foil or nickel foam are not used, because of their rigid nature that does not satisfy the scope of the present study dealing with development of flexible devices.…”