1D Hematite-[α-Fe2O3]-nanorods prepared by green fabrication for supercapacitor electrodes

1D α-hematite nanorods synthesized by a simple, scalable and novel green chemistry method exhibit fast kinetics of the interfacial Faradaic redox reaction yielding a specific capacitance of 140 F·g−1 when used as a battery-type electrode in a supercapacitor. Ample supply and environmental compatibility of the raw material suggest the use of this material. Insufficient stability suggest further investigations.

A three-dimensional conducting network of rGO-in-graphite-felt as electrode for vanadium redox flow batteries

Graphite felt (GF) with numerous merits has been widely used as electrode in all-vanadium redox flow batteries (VRFB), but its further application is still hindered by its intrinsically poor electrocatalytic activity. Herein, we propose a three-dimensional (3D) conducting network constructed with reduced graphene oxide (rGO) in the GF electrode via a two-step method. The 3D conducting network with abundant oxygen-containing functional groups in the GF is conducive to the transport of electrons between GF fibers and the electrochemical charge transfer to vanadium ions in the composite electrode; it can enhance the electrocatalytic activity and conductivity of GF. The VRFB using 3D rGO modified GF (mGF) electrode exhibited outstanding energy efficiency of 73.4% at a current density of 100 mA·cm−2, which is much higher than that with pristine GF (pGF) (65.4%); and better rate capability. These first results reveal that GF with 3D conducting network shows promising opportunities for the VRFB and other electrochemical flow systems

Effect of magnesium sulfate on the electrochemical behavior of lead electrodes for lead acid batteries

The lead acid battery technology has undergone several modifications in the recent past, in particular, the electrode grid composition, oxide paste recipe with incorporation of foreign additives into the electrodes and similarly additives added in the electrolytes to improve electrical performance of the lead acid battery. In this paper, the electrochemical behavior of the lead electrodes with different weight/volume percentages (wt./v%) of MgSO4(0.0., 0.5., 1.0., 2.0., and 5.0) added into the electrolyte have been investigated with cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The CV profile showed better redox behavior of the lead electrodes which was attributed to the increased active surface area of the electrode. Further studies of the gas evolution found a mixed trend and a considerable drop in the impedance as observed by LSV and EIS analysis as compared to the blank electrolyte solution. The influence of a modified electrolyte on the electrochemical activity of the lead electrodes is correlated and discussed.

Nano-TiO2 Phosphate Conversion Coatings – A Chemical Approach

The present study aims at deposition of zinc phosphate coatings on low carbon steel with incorporated nano- TiO2 particles by chemical phosphating method. The coated low carbon steel samples were assessed in corrosion studies using electrochemical impedance spectroscopy and potentiodynamic polarization techniques (Tafel) in 3.5% NaCl solution. Morphology and chemical composition of the coatings were analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy in order to observe growth of coating. Significant variations in the coating weight, porosity and corrosion resistance were observed with the addition of nano- TiO2 in the phosphating bath. Corrosion rate of nano-TiO2 chemical phosphate coated samples was found to be 3.5 milli inches per year which was 3 times less than the normal phosphate-coated sample (8 mpy). Electrochemical impedance spectroscopy studies reveal reduction of porosity of nano-TiO2 phosphate coated samples. It was found that nano-TiO2 particles in the phosphating solution yielded uniform phosphate coatings of higher coating weight, fewer defects and enhanced corrosion resistance than the normal zinc phosphate coatings (developed using normal phosphating bath).

Partially Fluorinated Ether as an Electrolyte Additive to Modify Electrode Surface and Suppress Dissolution of Polysulfides in Li-S Batteries

Abstract1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), a kind of fluorinated ether, was used as an electrolyte additive for Li-S batteries. A compact, smooth, and homogenous surface layer was formed on lithium anode at the optimized amount of added TTE. In addition, TTE additive played a crucial role in modifying the composition of the passivation layer on the sulfur/carbon cathode. Consequently, the dissolution and shuttling of polysulfides were effectively prevented. The reversible capacity, initial coulombic efficiency, electrode reaction kinetic, and cycling stability of Li-S batteries were greatly improved.

SnO2/PANI nanocomposite electrodes for supercapacitors and lithium ion batteries

Tin oxide (SnO2) nanostructures and SnO2/Polyaniline (PANI) nanocomposites to be used as electrode materials for a lithium ion battery were synthesized using a solution-route technique with chelating agents followed by calcination at 300∘C for 4 h. Structural and morphological properties were studied with powder X-ray diffraction, scanning electron and transmission electron microscopy. Particles of 25-10 nm size are observed in the microscope images. TGA results showed that the PANI-modified SnO2 nanoparticles exhibit higher thermal stability than the SnO2 nanoparticles. Electrochemical properties of SnO2 and SnO2/PANI electrodes were examined in a lithium ion battery and a supercapacitor. The electrode of SnO2/PANI shows higher specific capacity. The cell with SnO2/PANI exhibits a specific capacity of 1450 mAh/g at C/10. Supercapacitor results indicate that the PANI-modified SnO2 composite had a higher current with apparent cathodic and anodic peaks.

Carbon supported g-C3N4 for electrochemical sensing of hydrazine

This study reports a synthesis of carbon supported graphitic carbon nitride (g-C3N4-KBC) obtained by pyrolysis of melamine with Ketjenblack 600JD carbon (KBC) at 550°C for 4 h in a N2 atmosphere. g-C3N4-KBC oxidizes hydrazine at an onset potential 0.145 V vs. SCE close to the thermodynamic standard potential of hydrazine (0.23 V vs. SHE). In comparison to the controls, KBC and g-C3N4, g-C3N4-KBC oxidizes hydrazine at lower overpotential.Most research has tended to focus on transition metal-based catalysts and few are of carbon material such as graphene nanoflakes, graphene oxide, and carbon nanotubes. A comparison in terms of sensitivity, detection range and stability reveals g-C3N4-KBC electrode’s superiority over other carbon material-based catalysts. To the best of our knowledge, the g-C3N4-KBC catalyst is not reported for sensing hydrazine in the literature.

Electrodeposition of Polymer Nanostructures using Three Diffuse Double Layers: Polymerization beyond the Liquid/Liquid Interfaces

Nanostructured conducting polymers have received immense attention during the past few decades on account of their phenomenal usefulness in diverse contexts, while the interface between two immiscible liquids is of great interest in chemical and biological applications. Here we propose a novel Electrode(solid)/Electrolyte(aqueous)/Electrolyte(organic) Interfacial assembly for the synthesis of polymeric nanostructures using a novel concept of three diffuse double layers. There exist remarkable differences between the morphologies of the polymers synthesized using the conventional electrode/electrolyte method and that of the new approach. In contrast to the commonly employed electrodeposition at liquid/liquid interfaces, these polymer modified electrodes can be directly employed in diverse applications such as sensors, supercapacitors etc.

Preparation of Ti/IrO2 Anode with Low Iridium Content by Thermal Decomposition Process: Electrochemical removal of organic pollutants in water

In this study IrO2 (Iridium oxide) was coated onto a titanium plate anode from a dilute (50 mg/10 ml) IrCl3×H2O salt solution. Coating was done at high temperature (550∘C) using thermal decomposition. Surface morphology and characteristics of coated surface of Ti/IrO2 anode were examined by FESEM and XRD. The coated anode was applied for electrochemical removal of organic pollutants from synthetic water samples in 100 mL compartment of batch electrochemical cell. About 50% COD removal was obtained at anode prepared with low Ir content solution while 72% COD removal was obtained with anode prepared at high Ir content. Maximum COD removal was obtained at 10 mA/cm2 current density.

Study on Electrical conductivity and Activation Energy of doped Ceria nanostructures

Ce0.8Gd0.2O2−δ (GDC) and Ce0.8Sm0.2O2−δ (SDC) nanocrystalline materials are prepared by a solid state reaction method. The synthesized nano crystalline solid solutions have cubic fluorite structure as evident from XRD patterns. The materials are qualitatively analyzed by FTIR. The morphology, size and shape of grains etc. are identified from the SEM images. The grain size of GDC is smaller than that of SDC. The better morphology is obtained for GDC. Hence, this is electrically characterized. The activation energy is calculated from the slope of Arrhenius plot (showing variation of conductivity with temperature).