Highly Uniform Atomic Layer-Deposited MoS₂@3D-Ni-Foam: A Novel Approach To Prepare an Electrode for Supercapacitors

Abstract

This article takes an effort to establish the potential of atomic layer deposition (ALD) technique toward the field of supercapacitors by preparing molybdenum disulfide (MoS) as its electrode. While molybdenum hexacarbonyl [Mo(CO)] serves as a novel precursor toward the low-temperature synthesis of ALD-grown MoS, HS plasma helps to deposit its polycrystalline phase at 200 °C. Several ex situ characterizations such as X-ray diffractometry (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and so forth are performed in detail to study the as-grown MoS film on a Si/SiO substrate. While stoichiometric MoS with very negligible amount of C and O impurities was evident from XPS, the XRD and high-resolution transmission electron microscopy analyses confirmed the (002)-oriented polycrystalline h-MoS phase of the as-grown film. A comparative study of ALD-grown MoS as a supercapacitor electrode on 2-dimensional stainless steel and on 3-dimensional (3D) Ni-foam substrates clearly reflects the advantage and the potential of ALD for growing a uniform and conformal electrode material on a 3D-scaffold layer. Cyclic voltammetry measurements showed both double-layer capacitance and capacitance contributed by the faradic reaction at the MoS electrode surface. The optimum number of ALD cycles was also found out for achieving maximum capacitance for such a MoS@3D-Ni-foam electrode. A record high areal capacitance of 3400 mF/cm was achieved for MoS@3D-Ni-foam grown by 400 ALD cycles at a current density of 3 mA/cm. Moreover, the ALD-grown MoS@3D-Ni-foam composite also retains high areal capacitance, even up to a high current density of 50 mA/cm. Finally, this directly grown MoS electrode on 3D-Ni-foam by ALD shows high cyclic stability (>80%) over 4500 charge-discharge cycles which must invoke the research community to further explore the potential of ALD for such applications.

Enhanced Thermal Decomposition Properties and Catalytic Mechanism of Ammonium Perchlorate over CuO/MoS2 Composite

“…The phase structures of as‐obtained MoS 2 , CuO and 50%‐CuO/MoS 2 were first confirmed by XRD measurement, as shown in Figure S3. The peaks at 14°, 33° and 59° can be well indexed to the hexagonal phase of MoS 2 (PDF 89–2905), while the characteristic peaks of CuO were shown at 35°, 38°, 53°, 58°, 61°, 72°, 75° and 83° (PDF 89–2529) . After loading CuO, there were related peaks attributed to CuO appearing on the XRD patterns of MoS 2 , indicating the successful CuO loading.…”

Molybdenum Disulphide Heterointerfaces as Potential Materials for Solar Cells, Energy Storage, and Hydrogen Evolution

“…These investigations confirm that there is (002)‐oriented polycrystalline growth of the hexagonal‐MoS 2 phase. The cyclic voltammeteric measurements of supercapacitors constructed by these electrodes show the Faradic behavior, the optimized devices showed a reasonably high areal capacitance of 3400 mF cm −2 at the current density of 3 mA cm −2 , and the further retention rate was found to be better even at the current density of 50 mA cm −2 with 80% cyclic stability . The sodium‐ion intercalation in MoS 2 interlayers increases in phosphorus‐mediated MoS 2 nanowires.…”

2D Transition Metal Dichalcogenide Thin Films Obtained by Chemical Gas Phase Deposition Techniques

“…Furthermore, diffusion of the ions into the films at slow scan rates gives rise to Faradaic capacitance, which enhances the capacitance significantly, showing an areal capacitance of 71 mF cm −2 at a 1 mV s −1 scan rate. Nandi et al utilized MoS 2 as an electrode on 2D stainless steel and on 3D Ni‐foam substrates and revealed the advantage of using ALD for growing a conformal thin film . The optimized number of ALD cycles was estimated to be 400 for the MoS 2 on 3D‐Ni‐foam electrode to achieve the maximum areal capacitance of 3.4 F cm −2 , showing both Faradaic reactions and double‐layer capacitance with reasonably good cycling stability up to 4500 cycles, as shown in Figure a–d.…”

“…d) Cycling stability as revealed by the capacitance retention and the corresponding CE for MoS 2 @3D‐Ni foam grown by 400 ALD cycles (inset, the last few charge–discharge cycles). (a–d) Reproduced with permission . Copyright 2017, American Chemical Society.…”

“…However, the restacking between the nanosheets and the relative brittleness of WS 2 limit its applications. To solve this problem, fabrication in core–shell and/or 3D structured forms has been applied to improve the mechanical properties . On the other hand, highly conductive carbon materials have been applied to prevent the restacking of WS 2 and enhance the electrical properties .…”