Directly Sputtered Molybdenum Disulfide Nanoworms Decorated with Binder-less VN and W₂N Nanoarrays for Bendable Large-Scale Asymmetric Supercapacitor

Abstract

Considering the superior capacitive performance and rich redox kinetics, the two-dimensional (2D) layered molybdenum disulfide (MoS2) and transition metal nitrides (TMNs) have emerged as the latest set of nanomaterials. Direct incorporation of key materials vanadium nitride (VN) and tungsten nitride (W2N) into a MoS2 array has been achieved on cost-effective, bendable stainless steel (SS) foil via a reactive cosputtering route. Herein, we have utilized the synergistic effect of intermixed nanohybrids to develop a flexible asymmetric supercapacitor (FASC) device from MoS2–VN@SS (negative) and MoS2–W2N@SS (positive) electrodes. As-constructed FASC cell possesses a maximum operational potential of 1.80 V and an exceptional gravimetric capacitance of 200 F g–1 at a sweep rate of 5 mV s–1. The sustained capacitive performance mainly accounts for the synergism induced through unique interfacial surface architecture provided by MoS2 nanoworms and TMN conductive hosts. The sulfur and nitrogen edges ensure the transport channels to Li+/SO4 –2 ions for intercalation/deintercalation into the composite nanostructured thin film, further promoting the pseudocapacitive behavior. Consequently, the supercapacitor cell exhibits a distinctive specific energy of 87.91 Wh kg–1 at 0.87 kW kg–1 specific power and a reduced open circuit potential (OCP) decay rate (∼42% self-discharge after 60 min). Moreover, the assembled flexible device exhibits nearly unperturbed electrochemical response even at bending at 165° angle and illustrates a commendable cyclic life-span of 82% after 20,000 charge–discharge cycles, elucidating advanced mechanical robustness and capacitance retentivity. The powering of a multicolor light-emitting diode (LED) and electronic digital watch facilitates the practical evidence to open up possibilities in next-generation state-of-the-art wearable and miniaturized energy storage systems.

Applicability of the MoS2–aSiC Heterostructure for Durable Supercapacitance and NO2 Gas Sensing in a Harsh Environment

“…It also includes the diffraction peaks centered at 43.60 and 50.78° Bragg angles corresponding to the SS substrate. These peaks were indexed as (111) and (200), respectively, from the JCPDS card 00-003-0397 of iron . Further, the aSiC film on the SS substrate demonstrated no diffraction peaks except for the SS substrate, revealing the amorphous nature of the sample.…”

“…The schematics and corresponding circuits are shown in Figure a. The gravimetric capacitance C (F/g) values from cyclic voltammetry (CV) plots as well as from the galvanostatic charge–discharge (GCD) plots, and Coulombic efficiency (η %) were calculated using the following formulas C = q m normalΔ V = ∫ I ( V ) normald V italicmv normalΔ V where q = total charge, m = mass of the deposited materials, v = scan rate (V/s), Δ V = voltage window, and ∫ I ( V )d V = area of the CV loop. C = i normalΔ t m normalΔ V = true( i m true) true( normalΔ V normalΔ t true) where ( i m ) = current density and Δ t = discharging time. η = t normald t normalc % where t d = discharge time and t c = charging time.…”

“…The success of expeditions for scientific exploration in these locations crucially depends on the payloads consisting of electronic devices manifesting stable responses under such conditions. Today, researchers focus on materials demonstrating stable device performance for various applications in extreme conditions. , It is usually observed that the highly active materials for some applications suffer from less stability. , For instance, metal oxides, transition-metal dichalcogenides (TMDs), metal nitrides, etc., exhibit high energy storage capability, but their stability in aqueous electrolytes is inferior. , These problems are usually caused by poor adhesion of the active materials to the substrate, loosely bound constituents of the materials, irreversible side product formation during device operation, structural deformations, etc. To overcome this issue, numerous techniques are being incorporated, such as composite and heterojunction formation, binder usage, porous substrates, employing suitable fabrication techniques such as one-step sputtering, etc .…”

“…For the stability of the active material in a harsh environment, the large number of alternate layers seems rational instead of a smaller number of thick layers due to the increased number of adhesive aSiC layers. The supercapacitor and gas sensor commonly work with a similar mechanism where adsorption and desorption of electrolyte ions and gas molecules, respectively, are required. , Therefore, the strategies to enhance the supercapacitor and gas sensor response are quite similar. It is usually carried out by increasing the active surface area by tailoring the morphology, surface modification by noble metal nanoparticle decoration, composite and heterostructure formation, doping with suitable materials, porosity enhancement, crystallinity tuning, grain boundary modification, etc.…”

“…The supercapacitor and gas sensor commonly work with a similar mechanism where adsorption and desorption of electrolyte ions and gas molecules, respectively, are required. , Therefore, the strategies to enhance the supercapacitor and gas sensor response are quite similar. It is usually carried out by increasing the active surface area by tailoring the morphology, surface modification by noble metal nanoparticle decoration, composite and heterostructure formation, doping with suitable materials, porosity enhancement, crystallinity tuning, grain boundary modification, etc. Therefore, the heterostructure of aSiC with MoS 2 with alternate layers can significantly improve the supercapacitor and gas sensor responses along with significant stability.…”