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Nickel hydroxide deposited indium tin oxide electrodes as electrocatalysts for direct oxidation of carbohydrates in alkaline medium
No full textIn this work, the direct electrochemical oxidation of carbohydrates using nickel hydroxide modified indium tin oxide (ITO) electrodes in alkaline medium is demonstrated; suggesting the feasibility of using carbohydrates as a novel fuel in alkaline fuel cells applications. The chosen monosaccharides are namely glucose and fructose; disaccharides such as sucrose and lactose; and sugar acid like ascorbic acid for this study. ITO electrodes are chemically modified using a hexagonal lyotropic liquid crystalline phase template electrodeposition of nickel. Structural morphology, growth, orientation and electrochemical behaviour of Ni deposits are characterized using SEM, XRD, XPS and cyclic voltammetry (CV), respectively. Further electrochemical potential cycling process in alkaline medium is employed to convert these
Ni deposits into corresponding nickel hydroxide modified electrodes. These electrodes are used as novel platform to perform the electrocatalytic oxidation of various carbohydrates in alkaline medium. It was found that bare and Ni coated ITO electrodes are inactive towards carbohydrates oxidation. The heterogeneous rate constant values are determined and calculated to be two orders of magnitude higher in the case of template method when compared to non-template technique. The observed effect is attributed to the synergistic effect of higher surface area of these deposits and catalytic ability of Ni(II)/Ni(III) redox coupl
Ex-situ dispersion of core–shell nanoparticles of Cu–Pt on an in situ modified carbon surface and their enhanced electrocatalytic activities
No full textDirect dispersion of core–shell nanoparticles on a carbon support (Cu@Pt/C) has been achieved while retaining the essential core–shell features of the nanoparticles by adopting an in situ surface modification-cum-anchoring strategy
Competitive wetting of acetonitrile and dichloromethane in comparison to that of water on functionalized carbon nanotube surfaces
No full textDifferential wetting of pristine and ozonized carbon nanotubes has been studied using solvents
like acetonitrile and dichloromethane in comparison to the well-known wetting behavior of water.
Based on their unique structural and physical properties, functionalized CNT substrates have
been used due to the fact that independent variation in molecular as well as electronic properties
could be controlled by understanding the wetting of these liquids on carbon nanotubes (CNTs),
both pristine as well as ozone treated. The sensitivity of the wetting behavior with respect to
molecular interactions has been investigated using contact angle measurements while Raman and XPS studies unravel the differential wetting behavior. Charge-transfer between adsorbed molecules and CNTs has been identified to play a crucial role in determining the interfacial energies of these two liquids, especially in the case of acetonitrile. Ozone treatment has been observed to affect the surface properties of pristine CNTs along with a concomitant change
in the wetting dynamics
Model for corrosion of metals covered with thin electrolyte layers:pseudo-steady state diffusion of oxygen
No full textA one-dimensional mathematical model is presented for the free corrosion of a bare metal surface (devoid of any oxide film) under a thin electrolyte layer using mixed potential theory where anodic metal dissolution is controlled by oxygen diffusion through the electrolyte layer and by the oxygen reduction at the metal surface. A pseudo-steady state is considered wherein the oxygen diffusion is at steady state while the metal and hydroxyl ions keep accumulating in the thin electrolyte layer due to a decoupling arising from the assumed Tafel laws for corrosion kinetics. Under free corrosion the oxygen diffusion is shown to depend on a non-linear boundary condition with a non-integer power on oxygen concentration at the metal surface which makes the model non-trivial. Analytical and numerical results for the oxygen
concentration at the metal surface, corrosion potential, and corrosion current density are reported which depend on several kinetic, thermodynamic and transport parameters in the system. The model is applied to iron and zinc systems with input data taken from the literature. The experimental utility of the model for gathering thin-film corrosion parameters from a study of the corrosion current and potential as a function of the thickness of the electrolyte layer is discussed. Precipitation and passivity, though not the main object of study in this work, are briefly discusse
Low-temperature growth of well-crystalline Co3O4 hexagonal nanodisks as anode material for lithium-ion batteries
No full textUniform hexagonal-shaped cobalt oxide (Co3O4) nanodisks were prepared in large scale via facile aqueous solution based hydrothermal process at 110 ◦C. The detailed structural characterizations confirmed that the synthesized products are hexagonal cobalt oxide nanodisks, possessing very well-crystalline cubic spinel structure. A coin cell of type
−2032 was assembled using the synthesized Co3O4 nanodisks and its charge–discharge profile was analyzed between the voltages 0.01 and to 2.5 V vs. Li/Li+ reference electrode. The electrochemical cell composed of Li/Co3O4 delivered an initial lithium insertion capacity of 2039 mAh/g. Although the cell exhibited high irreversible capacity during the first four cycles, the columbic efficiency has been improved upon cyclin
Products formed at intermediate stages of electrochemical perfluorination of propionyl and n-butyryl chlorides. Further evidence in support of NiF3 mediated free radical pathway
No full textThe partially fluorinated HF soluble intermediates formed during the electrochemical perfluorination of propionyl chloride (PC) and n-butyryl chloride (n-BC) were analyzed after passing 0%, 25%, 50%, 75% and 100% of theoretical charge required for the fluorination of PC and n-BC. The acid fluorides formed were converted to their corresponding sodium salt by alkali treatment and were separated by methanol extraction. The methanol was subsequently removed from the extract by vacuum distillation and the residue containing partially fluorinated sodium carboxylates was analyzed using 19F and 1H NMR spectra. Initial perfluorination on activated electrode surface indicates the operation of ‘zippermechanism’. Formation of partially fluorinated product mixture, initial selectivity towards primary and secondary carbon, carbon chain isomerization and formation of cleaved and coupled products support the general operation of free radical pathway in the overall electrochemical proces
Elecrokinetic separation of sulphate and lead from sludge of spent lead acid battery
No full textA novel electrokinetic (EK) technique is applied to separate lead and sulphate from the sludge of used/spent lead acid battery. XRD reveals that the sludge is a mixture of (PbO)4 [Pb(SO4)], Pb2O3, PbSO4, Pb(S2O3) and Pb2(SO4) which upon DC voltage application in a EK cell employing either titanium electrodes or titanium substrate insoluble anode as electrodes caused migration of sulphates and lead ions
respectively into anode and cathode compartments, and accumulation of insoluble lead oxides at the central compartment. The insoluble lead oxides accumulated at the central compartment in the ratio 1:3, respectively for the high oxygen over-voltage Ti-anode (Ti-EK cell) and low oxygen over-voltage TSIA-anode (TSIA-EK cell) shows the superiority of Ti anode over TSIA anode. Also thermal investigation reveals Pb deposited at Ti-cathode is superior to that from TSIA cathode. This process does not release
air/soil pollutants which are usually associated with high temperature pyrotechnic proces
Effects of alternating and direct current in electrocoagulation process on the removal of cadmium from water
No full textIn practice, direct current (DC) is used in an electrocoagulation processes. In this case, an impermeable
oxide layer may form on the cathode as well as corrosion formation on the anode due to oxidation. This prevents the effective current transfer between the anode and cathode, so the efficiency of electrocoagulation processes declines. These disadvantages of DC have been diminished by adopting alternating current (AC) in electrocoagulation processes. The main objective of this study is to investigate the effects of AC and DC on the removal of cadmium from water using aluminum alloy as anode and cathode. The results showed that the removal efficiency of 97.5 and 96.2% with the energy consumption of 0.454 and 1.002 kWh kl−1 was achieved at a current density of 0.2 A/dm2 and pH of 7.0 using aluminum alloy as electrodes using AC and DC, respectively. For both AC and DC, the adsorption of cadmium was preferably fitting Langmuir adsorption isotherm, the adsorption process follows second order kinetics and the
temperature studies showed that adsorption was exothermic and spontaneous in natur
Failure analysis of cast-on-strap in lead-acid battery subjected to vibration
No full textLead-acid batteries (LAB) are widely used in transportation sector for starting, lighting and
ignition application. The possibility of vibration mode of failure occurs in this application
due to wear and tear of the road. These vibration causes fatigue failure, particularly
between the cast on strap and pillar post leading to loss of electrical connection. In this
paper vibration test is conducted on a 12 V/75 Ah AGM Valve Regulated Lead-Acid Battery
(VRLAB) used for above mentioned application in India. The test is carried out using Electrodynamic
Vibration System model SD-10-240/GT500M/DA-10. The shaker is performed
with a sinusoidal excitation, with an acceleration of 2.143G and a fixed frequency of
16.7 Hz. The peak to peak displacement is 4 mm. The deformation and crack propagation
features on the surface and cross sectional area of pillar post and strap in both positive
and negative group are observed with Scanning Electron Microscope (SEM). The material
is yielded due to improper fusion between pillar post and strap which could not stand
the vibration force. During vibration this region is vulnerable for fatigue failure
Electrodeposition of nano crystalline nickel using pulse technique for hi-tech applications
No full textNickel is deposited from different electrolytes as sulphate, sulphamate, chloride for its various applications. Electrodeposition of nickel is used mostly for corrosion protection of steel and for both decorative and functional applications. Bright, Semi-bright coatings can be obtained from various compositions of electrolytes for its various requirements. Nickel is also used for electroforming purposes to fabricate critical components which cannot be produced by conventional fabrication processes. Some of the strategic components like rocket engine thrust chamber, missile cone, seamless crucible, engine for Reusable Launch vehicle and MEMS are fabricated by electroforming process; this process is also engaged in the preparation of mould for hologram, DVD, currency etc. The present study dealt with deposition of nano crystalline nickel from sulphamate electrolyte by direct current and pulsed current; surface morphology was studied by SEM, X-ray diffraction pattern of electrodeposited samples. The results are of impressive one that nano crystalline nickel was obtained in the order of 60 to 80 nanometers by pulse technique.
Electrodeposition of nano crystalline nickel using pulse technique for hi-tech applications. Available from: https://www.researchgate.net/publication/254020596_Electrodeposition_of_nano_crystalline_nickel_using_pulse_technique_for_hi-tech_applications [accessed Sep 20, 2017]