Band 4, Heft 1

In this study IrO 2 (Iridium oxide) was coated onto a titanium plate anode from a dilute (50 mg/10 ml) IrCl 3 ×H 2 O salt solution. Coating was done at high temperature (550∘C) using thermal decomposition. Surface morphology and characteristics of coated surface of Ti/IrO 2 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/cm 2 current density.

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.

This study reports a synthesis of carbon supported graphitic carbon nitride (g-C 3 N 4 -KBC) obtained by pyrolysis of melamine with Ketjenblack 600JD carbon (KBC) at 550°C for 4 h in a N 2 atmosphere. g-C 3 N 4 -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-C 3 N 4 , g-C 3 N 4 -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-C 3 N 4 -KBC electrode’s superiority over other carbon material-based catalysts. To the best of our knowledge, the g-C 3 N 4 -KBC catalyst is not reported for sensing hydrazine in the literature.

Tin oxide (SnO 2 ) nanostructures and SnO 2 /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 SnO 2 nanoparticles exhibit higher thermal stability than the SnO 2 nanoparticles. Electrochemical properties of SnO 2 and SnO 2 /PANI electrodes were examined in a lithium ion battery and a supercapacitor. The electrode of SnO 2 /PANI shows higher specific capacity. The cell with SnO 2 /PANI exhibits a specific capacity of 1450 mAh/g at C/10. Supercapacitor results indicate that the PANI-modified SnO 2 composite had a higher current with apparent cathodic and anodic peaks.

1,1,2,2-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.

The present study aims at deposition of zinc phosphate coatings on low carbon steel with incorporated nano- TiO 2 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- TiO 2 in the phosphating bath. Corrosion rate of nano-TiO 2 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-TiO 2 phosphate coated samples. It was found that nano-TiO 2 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).

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 MgSO 4 (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.

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