Supercapacitors are increasingly used for energy conversion and storage systems in sustainable nanotechnologies. Graphite is a conventional electrode utilized in Li-ion-based batteries, yet its specific capacitance of 372 mA h g−1 is not adequate for supercapacitor applications. Interest in supercapacitors is due to their high-energy capacity, storage for a shorter period and longer lifetime. This review compares the following materials used to fabricate supercapacitors: spinel ferrites, e.g., MFe2O4, MMoO4 and MCo2O4 where M denotes a transition metal ion; perovskite oxides; transition metals sulfides; carbon materials; and conducting polymers. The application window of perovskite can be controlled by cations in sublattice sites. Cations increase the specific capacitance because cations possess large orbital valence electrons which grow the oxygen vacancies. Electrodes made of transition metal sulfides, e.g., ZnCo2S4, display a high specific capacitance of 1269 F g−1, which is four times higher than those of transition metals oxides, e.g., Zn–Co ferrite, of 296 F g−1. This is explained by the low charge-transfer resistance and the high ion diffusion rate of transition metals sulfides. Composites made of magnetic oxides or transition metal sulfides with conducting polymers or carbon materials have the highest capacitance activity and cyclic stability. This is attributed to oxygen and sulfur active sites which foster electrolyte penetration during cycling, and, in turn, create new active sites.

/pdf/advanced-materials-and-technologies-for-supercapacitors-used-4rybecybwk.pdf

Advanced materials and technologies for supercapacitors used in energy conversion and storage: a review

Recent progress and emerging challenges of transition metal sulfides based composite electrodes for electrochemical supercapacitive energy storage

Construction of nickel cobalt sulfide nanosheet arrays on carbon cloth for performance-enhanced supercapacitor

NiCo2S4-based nanocomposites for energy storage in supercapacitors and batteries

Template-assisted synthesis of hierarchically hollow C/NiCo2S4 nanospheres electrode for high performance supercapacitors

Fabrication of hierarchical NiCo2S4@CoS2 nanostructures on highly conductive flexible carbon cloth substrate as a hybrid electrode material for supercapacitors with enhanced electrochemical performance

The real-time monitoring of hydrogen peroxide (H2O2) production in living cells is of paramount importance; however, the high complexity of biological fluids and low concentrations of in-vivo H2O2 are limiting the sensor’s sensitivity and selectivity. Here, we described a carbon cloth (CC) modified nickel cobalt sulfide/cobalt sulfide nanostructured arrays (NiCo2S4@CoS2 NAs) as a highly sensitive and selective electrochemical transducer for tracking endogenous H2O2 production in real-time. A hydrothermal synthetical procedure was adopted to deposit the nanostructured arrays. NiCo2S4, an important class of binary transition metal dichalcogenide holds outstanding electrocatalytic activity thanks to its redox properties, enlarged electrocatalytic sites due to mixed valence states, and high conductivity. The growth of NiCo2S4 in association with cobalt disulfide CoS2 on a 3D conducting backbone leads to the nanostructured arrays. The structure, size of the particles, crystallinity, and composition of the arrays were analyzed by the state-of-the-art high-vacuum surface techniques. The NiCo2S4@CoS2 NAs@CC was found to have excellent electrocatalytic performance to reduce H2O2. The electrode displayed a rapid, sensitive, and durable amperometric sensing characteristics, over a linear range of 12.64 nM–2104 μM. The detection limit was 2 nM (S/N = 3). The sensor was able to quantify the amount of endogenously produced H2O2 released from Raw 264.7 cells. Thus, the binary TMDs based nanostructures have promising potential in live cell biosensing applications.

Real-time quantification of hydrogen peroxide production in living cells using NiCo2S4@CoS2 heterostructure

Carbon fabrics are the new generation promising electrode materials for super capacitors owing to their high electrical conductivity, high chemical stability and low thermal expansion. In this work, 2D-MoS2 nanostructures have been successfully deposited over the commercially available carbon fabric by hydrothermal approach, using silicontungstic acid as an additive. MoS2 nanostructures – carbon fabric was broadly characterized using XRD, FESEM and Raman Spectroscopy. XRD patterns indicated that the fabricated MoS2 nanoparticles can be indexed to hexagonal (2H) and rhombohedral (3R) phases. FESEM images revealed the formation of hierarchical 2D MoS2 nanosheets arranged in a nanosphere like morphology over the carbon fabric. The electrochemical behavior of the MoS2 - carbon fabric and commercially available bare carbon fabric were studied using cyclic voltammetry analysis with different scan rates. The MoS2-carbon fabric exhibited an excellent electrochemical performance with a specific capacitance of 441 F/g at a scan rate of 10mV/s. The good cyclic behavior with symmetric charging/discharging curves, constant specific capacitance for longer scan rates, suggesting that the MoS2- carbon fabric electrode is a potential electrode material for high power applications.

/pdf/formation-of-hierarchical-2d-mos2-nanostructures-over-carbon-jywrag1drz.pdf

Selvaraj Shanthi

Papers

Fabrication of hierarchical NiCo2S4@CoS2 nanostructures on highly conductive flexible carbon cloth substrate as a hybrid electrode material for supercapacitors with enhanced electrochemical performance

Real-time quantification of hydrogen peroxide production in living cells using NiCo2S4@CoS2 heterostructure

Formation of Hierarchical 2D-Mos2 Nanostructures over Carbon Fabric as Binder Free Electrode Material for Supercapacitor Applications