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Metal sulfide-based electrodes played a vital in energy storage applications due to novel characteristics, i.e., facile synthesis, relatively higher electronic conductivity and fast switching between redox states. This study presents the synthesis of chromium sulfide and reduced graphene oxide (rGO)-based electrodes in parallel to structural, morphological and electrochemical characterizations performed for supercapacitor applications. Individual chromium sulfide and reduced graphene oxide reveal the pseudocapacitive behavior in cyclic voltammetry (CV) curves with the maximum specific capacitance of 522.84 and 3.77 F/g, respectively, at the scan rate of 5 mV/s. Galvanostatic charge–discharge (GCD) measurements showed that Individual chromium sulfide exhibited a good specific capacitance of 710.90 F/g and energy density of 24.68 Wh/Kg at the applied current density of 3 mA/cm2, while the power density of 1028.81 W/Kg at 6 mA/cm2. CV curves of the asymmetric system consisting of chromium sulfide with reduced graphene oxide also revealed the pseudocapacitive behavior. The specific capacitance through CV curves has been found as 24.53 F/g at 10 mV/s, while a specific capacitance from GCD profile has been measured as 26.41 F/g at a current density of 4 μA/cm2. Moreover, the power density of the asymmetric system has been found as 780.35 W/Kg and indicated a suitable electrode structure for supercapacitor applications. This study is a first attempt to present the development of asymmetric cell of rGO and chromium sulfide-based electrodes which is highly feasible for high power density in parallel to reasonable energy density as per the demand of modern energy storage devices. [ABSTRACT FROM AUTHOR]

Composite materials and their applications constitute a hot field of research nowadays due to the fact that they comprise a combination of the unique properties of each component of which they consist. Very often, they exhibit better performance and properties compared to their combined building blocks. Graphene oxide (GO), as the most widely used derivative of graphene, has attracted widespread attention because of its excellent properties. Abundant oxygen-containing functional groups on GO can provide various reactive sites for chemical modification or functionalization of GO, which in turn can be used to develop novel GO-based composites. This review outlines the most recent advances in the field of novel dyes and pigments encompassing GO as a key ingredient or as an important cofactor. The interactions of graphene with other materials/compounds are highlighted. The special structure and unique properties of GO have a great effect on the performance of fabricated hybrid dyes and pigments by enhancing the color performance of dyes, the anticorrosion properties of pigments, the viscosity and rheology of inks, etc., which further expands the applications of dyes and pigments in dyeing, optical elements, solar-thermal energy storage, sensing, coatings, and microelectronics devices. Finally, challenges in the current development as well as the future prospects of GO-based dyes and pigments are also discussed. This review provides a reference for the further exploration of novel dyes and pigments. [ABSTRACT FROM AUTHOR]

Metal oxide based electrodes are attractive for energy storage applications with limited characteristics of flexibility due to inherent rigid structure. However, incorporation of flexible insulating matrix within metal oxide composites result in poor electrically conductive and energy storage characteristics. This study presents the fabrication of flexible MnO2 based composite electrodes prepared by incorporation of lignocelluloses (LC) fibers, directly collected from a self-growing plant, Monochoria Vaginalis. Furthermore electrodeposition of silver (Ag) nanoparticles was performed on LC/MnO2 in potentiostatic mode to address the electrically conductive characteristics. Morphology, structural, conductive and energy storage properties of fabricated electrodes are analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), impedance analyzer and potentiostat, respectively. SEM images clearly indicate the deposition of Ag nanoparticles on MnO2 nanorods embedded in LC fibers whereas FTIR results confirm the bonding of the functional groups. Cyclic voltammetry measurements showed efficient kinetics of LC/MnO2 after electrodeposition of Ag nanoparticles. The effects on electrical properties associated with blending MnO2 nanorods in lignocelluloses fibers and Ag deposition on MnO2 in LC/MnO2 are explored in wide frequency range between 10 Hz and 5 MHz. However, deposition of Ag nanoparticles on MnO2 nanorods surfaces acts as a conductive path and reduces the associated resistance. Incorporated flexibility in rigid structure of MnO2 and further improvements in conductive and energy storage characteristics will open the possibilities to be used as electrode in modern bendable energy storage devices. [ABSTRACT FROM AUTHOR]

Abstract: Surface morphology induced electrical conductivity and specific surface area of a material play a significant role to facilitate electrochemical behavior for supercapacitor application. Therefore, the synthesis step for controlling such parameters becomes very imperative and challenging. Herein, a ZnS nanoweb is deposited directly onto Ni foam with a pre‐deposited thin layer of hydrothermally prepared graphene oxide. The structure and surface morphology of the deposited ZnS is observed using XRD and SEM, respectively. The electrical conductivity of the graphene oxide supported ZnS nanoweb, determined using the four probes method, is 100.15 S cm−1. The specific surface area is 104.42 m2 g−1 as determined by BET measurements. Pseudocapacitive behavior is monitored by cyclic voltammetry, and the excellent specific capacity of 3052 Fg−1 has been found at a scan rate of 2 mV s−1, while it is 2400.30 Fg−1 according the galvanostatic charge‐discharge profile at a current density of 3 mA cm−2. Both values are significantly higher than those measured for bare GO or ZnS layers. The energy and power densities of GO supported ZnS nanoweb are determined in a three electrode setup, are 120 Wh Kg−1 at 3 mA cm−2 and 4407.73 Wkg−1, respectively. In a symmetric two electrode setup, an energy density of 20.29 Wh Kg−1 at 2 mA cm−2 is observed. Hence, both symmetric and asymmetric measurements suggest that GO supported ZnS nanoweb can be applied as a suitable electrode for supercapacitors. [ABSTRACT FROM AUTHOR]

In the new era of modern flexible and bendable technology, graphene-based materials have attracted great attention. The excellent electrical, mechanical, and optical properties of graphene as well as the ease of functionalization of its derivates have enabled graphene to become an attractive candidate for the construction of flexible devices. This paper provides a comprehensive review about the most recent progress in the synthesis and applications of graphene-based composites. Composite materials based on graphene, graphene oxide (GO), and reduced graphene oxide (rGO), as well as conducting polymers, metal matrices, carbon–carbon matrices, and natural fibers have potential application in energy-harvesting systems, clean-energy storage devices, and wearable and portable electronics owing to their superior mechanical strength, conductivity, and extraordinary thermal stability. Additionally, the difficulties and challenges in the current development of graphene are summarized and indicated. This review provides a comprehensive and useful database for further innovation of graphene-based composite materials. [ABSTRACT FROM AUTHOR]

Owing to large specific surface area and high electrical conductivity, nanostructured electrodes exhibit improved electrochemical activity for supercapacitor applications. In the present study, structure and morphology of hydrothermally synthesized strontium sulfide and graphene oxide based Strontium sulfide nanorods have been investigated by using XRD and SEM, respectively. Introduction of graphene oxide thin film improves specific surface area and result in the excellent electrical conductivity of Strontium sulfide nanorods. Due to this, graphene oxide based strontium sulfide nanorods illustrate excellent specific capacitance and energy density of 1831.14 F g −1 and 91.56 WhKg −1 , respectively, at the current density of 3 mAcm −2 , as measured by employing three electrode galvanostatic charge discharge system. Moreover, electrode of graphene oxide based strontium sulfide nanorods also shows good electrochemical performance, according to the measurements by symmetric two electrode system. Energy and power density is measured as 10.55 WhKg −1 and 294.35 W kg −1 , respectively. The excellent electrochemical performance of graphene oxide based strontium sulfide nanorods reveals its significance as nanostructured materials for supercapacitor applications. [ABSTRACT FROM AUTHOR]

• The synthesized materials exhibited a rod-like morphology. • Nd-MOFs/GO composite-based electrode had a specific capacitance of 633.5 Fg−1 at a current density of 0.3 Ag−1, which is significantly higher than that of the Nd-MOFs (11.3 Fg−1). • The lowest ESR of 0.8 Ω for the Nd-MOFs/GO electrode. • At a current density of 3 Ag−1, Nd-MOFs/GO composite electrode showed a coulombic efficiency of 95.1% and cyclic stability of 88.67% after 4000 cycles. • Nd-MOF/GO exhibited enhanced pseudo-capacitance, coulombic efficiency, and reversibility, making it a promising active material for super-capacitor electrodes. Efficient energy storage and delivery of electrical energy is necessary for the use of advanced electrode materials in super-capacitors, rendering their development pivotal. We employed simple and economical hydrothermal technique to synthesize Nd-metal organic frameworks (MOFs) and Nd-MOFs/GO composite and evaluated their suitability as electrode materials through comprehensive investigation. Characterizations of the synthesized materials were done by various techniques, including XRD, FTIR (using ATR method) and SEM. Based on the results obtained, it was found that the Nd-MOFs/GO composite-based electrode had a specific capacitance of 633.5 Fg−1 when tested at a current density of 0.3 Ag−1, which is significantly higher than that of Nd-MOFs electrode (11.3 Fg−1). Additionally, electrochemical impedance spectroscopy (EIS) analysis demonstrated the lowest equivalent series resistance (ESR) of 0.8 Ω for the Nd-MOFs/GO electrode. The Nd-MOFs/GO composite electrode exhibited a cyclic stability of 88.76 % after 4000 cycles and coulombic efficiency of 95.1%, when subjected to a current density of 3 Ag−1. Moreover XRD showed that the synthesized hybrid exhibited an improved crystallinity of the hexagonal phase. The FTIR analysis using ATR method confirmed the presence of organic ligands and functional groups in the synthesized materials. The results of our study indicate that the Nd-MOFs/GO hybrid nanocomposite-based electrode material holds potential as a highly efficient candidate for super-capacitor applications. The reported method of synthesizing MOFs provides an effective approach to fabricate new electrode materials with excellent electrochemical characteristics. [ABSTRACT FROM AUTHOR]

Graphene oxide based electrode materials show remarkable electrochemical properties due to the improved specific surface area and electrical conductivity for supercapacitor applications. Hydrothermally synthesized graphene oxide based aluminum sulfide nanowalls on nickel foam (NF) have revealed excellent pseudocapacitive behavior with the specific capacitance 2362.15 F g -1 at 2 mVs -1 as observed through cyclic voltammetry. The galvanostatic charge-discharge measurements confirmed a specific capacitance 2373.51 F g -1 at 3 mAcm −2 . Hexagonal phase of the graphene oxide (GO) based Al 2 S 3 nanowalls also showed good discharge time of 820 s and energy density 118.68 WhKg −1 at 3 mAcm −2 . Moreover, the fabricated electrode material exhibited good power density 2663.58 W kg -1 at 20 mAcm −2 . The impedance results also confirmed the pseudocapacitive characteristics and revealed weak contact and Warburg resistances for the electrode material in half cell. Hence, GO based Al 2 S 3 nanowalls performed as a prominent electrode material for asymmetric supercapacitors. Additionally, electrode material also exhibited excellent symmetric behavior, which again suggested a good electrode structure for supercapacitor applications. [ABSTRACT FROM AUTHOR]