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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.

Graphene has drawn a great attention in the recent research innovations mainly due to its structural geometry, which is composed of one-atom thick planar sheet of hexagonally arrayed sp2 carbon atoms. Development of nanocomposites utilising graphene as the nanofiller offer desired properties to the added polymer matrix. Furthermore, incorporation of functional groups such as hydroxyl, epoxy, carboxyl, etc. on the basal plane of graphene enhances the interaction with the polymer matrices. Better interaction between the nanofiller and the polymer leads to exfoliation of the nanofiller in the matrices, which indeed significantly improves the physical, mechanical, thermal, electrical, electronic properties, etc., of the polymer. The review article explores the recent research findings on the development of polymeric nanocomposites utilising pure and functionalised graphene. The article focuses on the method of synthesis of graphene and functionalised graphene, followed by their characterisation methods and inferences. It also summarises the routes for the preparation of graphene and modified graphene-based polymer nanocomposites. The work highlights the enhancement of properties observed due to the addition of graphene and modified graphene to the polymer matrices. Several surface modifications done on GNS in order to achieve better dispersion of the same in the polymer matrix has been discussed. The review article portrays the recent research reports on graphene and modified graphene-based polymer nanocomposites. Techniques such as cryomilling, latex technology and lyophilisation as applied to polymer nanocomposites have been reviewed. Also, each of the literatures has been reviewed under the synthesis of filler and the preparation of the polymer nanocomposite separately which would serve as a guidance for future research. Literatures in which different carbon nanofillers have been compared to find the optimum filler has also been discussed.

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