Electrocatalytic oxidation of methanol on Pt modified polyaniline in alkaline medium

A comparative study of the electrocatalytic oxidation of methanol is made in NaOH, Na2CO3 and NaHCO3 on bare Pt (Pt), polyaniline covered Pt (PANI) and Pt modified polyaniline film on Pt (Pt/PANI) using cyclic voltammetry, polarization, ac impedance spectroscopy and chronoamperometric techniques at 25 °C. The cyclic voltammetry and polarization studies show that the potentials at which methanol oxidation commences on different electrodes in each of the alkaline medium examined follow the trend Pt/PANI < Pt < PANI whereas the potentials for initiation of oxidation on each electrode in different alkaline media follow the order NaHCO3 > Na2CO3 > NaOH. The oxidation current is highest and charge transfer resistance lowest for Pt/PANI films compared to Pt in all the media studied. However, for the same Pt loading Pt/PANI films exhibit larger oxidation currents in NaOH followed by Na2CO3 and NaHCO3. The Tafel slope for methanol oxidation on Pt/PANI in NaOH, Na2CO3 and NaHCO3 has a value of about 115 mV decade-1. The chronoamperometric response of the Pt/PANI film at the peak potential for methanol oxidation shows lesser sensitivity to poisoning by CO compared to bare Pt and platinised Pt (Pt/Pt). © 2008 Elsevier B.V. All rights reserved

Electrocrystallization of cadmium on copper single crystal planes under the influence of an asymmetric alternating current

Cadmium grows with a {0001} preferred orientation when electrodeposited on copper single crystals with pure dc. Superimposed alternating current in suitable ratios with dc perfects the {0001} orientation in cadmium deposits. The snowflake dendritic growth produced in cadmium deposits under the influence of superimposed ac of a higher magnitude appears to initiate at the corners of hexagonal platelets. This is probably due to the re-entrancies created by rotation induced twinning of the hexagonal platelets. © 1977

Electrocatalytic oxidation of methanol on Ni modified polyaniline electrode in alkaline medium

Electrolytically deposited Ni on polyaniline film covered carbon paste electrode (Ni/PANI/CPE) was used as anode for the electrooxidation of methanol in alkaline medium. The electrochemical behavior and electrocatalytic activity of the electrode were studied using cyclic voltammetry, impedance spectroscopy, chronomethods, and polarization studies. The morphology and composition of the modified film were obtained using scanning electron microscope and energy dispersive X-ray analysis techniques. The electrooxidation of methanol in NaOH was found to be more efficient on Ni/PANI/CPE than on bare Ni, electrodeposited Ni on Pt, Ni on glassy carbon, and Ni on CPE substrates. Partial chemical displacement of dispersed Ni on PANI with Pt or Pd further improved its performance towards methanol oxidation. © 2010 Springer-Verlag

Feasibility of double-layer microchannel fabrication at low speed micro end-mill and wire-cut EDM machines

This study compares micron-scale features of double layer-microchannel heat sink (DLMC) fabrication.Massive theoretical researches investigated DL-MC and its advantages over single-layer. However, micro-machining of DL-MC is still immature area. Here, Two advanced machining technologies, namely: Micro end-mill and wire-cut EDM are utilized to fabricate a DL-MC. Investigation on burr formation, surface roughness and shape configuration that influence heat transfer mechanism is done through a series of machining runs. Manipulating machine parameters such as: spindle speed, feed rate and tool dimension shown that low speed micro end-mill is capable of creating sufficient DL-MC quality. Also, scanning electron microscope (SEM) micrographs and roughness measurement reveal that wire-cutEDM is better in machining time and stability of surface roughness

Carbon paste electrodes modified by Pt and Pt-Ni microparticles dispersed in polyindole film for electrocatalytic oxidation of methanol

Electrocatalytic activity of the Pt microparticles dispersed into polyindole (PIn) films obtained by electropolymerization on carbon paste electrodes (CPE) towards methanol oxidation in perchloric acid medium has been demonstrated and investigated using cyclic voltammetry, potentiodynamic polarization, chronoamperometry and impedance spectroscopic techniques. The results show that PIn films obtained on these electrodes serve as good host matrices for the dispersion of Pt microparticles and exhibit good catalytic activity towards the electrooxidation of methanol compared to bulk Pt and CPE modified with Pt. The morphology and composition of the modified and unmodified films were obtained using SEM and EDX techniques. The effect of scan rate, amount of Pt and concentration of methanol, on the activity of the electrode has been tested. The effect of alloying Pt with different amounts of Ni was studied and it was found that when the metals are deposited from a solution containing the metal salts in 1:1 ratio the activity towards methanol oxidation was significantly enhanced. © 2009 Elsevier Ltd. All rights reserved

Electrocrystallization of zinc on copper single crystal planes under the influence of an asymmetric alternating current

Zinc electrodeposited from a sulphate bath on to copper single crystal planes revealed a layer-type growth on copper (111) and (100) planes and ridge-type growth on the (110) plane at low d.c. densities. Dendritic growth appeared at higher d.c. densities on all the planes. Superimposition of a.c. on d.c. during electrocrystallization produced hexagonal pyramids on the copper (111) plane, which were transformed into hexagonal dendrites under suitable a.c. to d.c. ratios. The influence of a.c. on the degree of epitaxy of zinc on copper and the mechanism of the dendrite initiation are discussed. © 1977 Chapman and Hall Ltd

Cyclic voltammetric studies of pure and doped films of cobalt hydroxide in 1M potassium hydroxide

Cyclic voltammetric studies of electrosynthetically prepd. pure and doped thin films of cobalt hydroxide (on a platinum foil substrate) in 1M KOH show that Co(OH)​2 undergoes a quasi-​reversible redox reaction between a nearly quadrivalent black oxidic phase and a trivalent brown bronze-​like phase. The coulombic efficiency is 60​%. A common scheme is proposed for the electrode reactions of oxide electrodes in alk. media, namely: MII(OH)​2 .dblharw. HMIIIO2 .dblharw. MIVO2, where M = Mn, Co, Ni. The three metals execute different steps in this two-​electron redox reaction, either reversibly or qu..

Electrochemical synthesis of Fe-Mo and Fe-Mo-Pt alloys and their electrocatalytic activity for methanol oxidation

Electroplating of Fe-Mo and Fe-Mo-Pt alloys has been carried out using suitable plating bath solutions and working conditions. The deposits were characterized by SEM, XRD, TEM, EDAX, XPS and Polarization techniques. New phases appeared on heat treatment of the coatings. The composition (Fe-Mo) of the coatings and oxidation states of the alloying elements varied from the surface to the bulk of the material. The coatings acted as novel electrode materials with good electrocatalytic activities (low overpotentials) and good corrosion resistance for the anodic oxidation of methanol in H2SO4 at normal working temperature. The good corrosion resistance of the Fe-Mo alloy is accounted for by the existence of an oxyhydroxide passive film on the surface. The electrocatalytic activity of the Fe-Mo-Pt alloy is considerably higher when compared to the Fe-Mo alloy and Fe alone

Fe-P and Fe-P-Pt co-deposits as hydrogen electrodes in alkaline solution

Fe-P and Fe-P-Pt alloys for use as electrodes for alkaline water electrolysis are prepared by an electroplating technique which employs an acidic complex bath solution. After heat treatment, the plated alloys act as effective electrocatalytic materials by lowering the hydrogen overpotential sufficiently. The improved electrocatalytic activity is due to an increase in effective surface area, a change in surface features upon heat treatment, and the presence of traces of platinum. Electrodes of the plated alloys are stable even in a highly corrosive electrolytic medium (6 M KOH). © 2001 Elsevier Science B.V. All rights reserved

Culture feasibility of african catfish (Clarias gariepinus Lin.) fry in glass tank and synthetic hapa system using supplemental diets

An experiment was carried out with 1 0 days old Clarias gariepinus fry over a period of 42 days to determine the effects of different feeds on growth and survival of African catfish fry in glass tanks. The experiment was designed into four treatments each having three replications. Thus treatment 1 (T1) was named as Tank Tubifex (TT) and treatment 2 (T2) as Tank Sabinco (TS), treatment 3 as Pond Tubifex (PT), and treatment 4 (T4) as Pond Sabinco (PS). Live Tubifex (protein levels 64.48%) was supplied to treatments 1 and 3 and rest of the treatments were supplied Sabinco starter-1 (protein levels 40.13%). The highest and the lowest growth in total length and weight were 12.90cm, 18.77g and 6.17cm, 4.04g recorded from the treatments 3 and 2, respectively. Growth of catfish fry under treatment 3 in terms of both length and weight were significantly higher (P<0.01) than those of the other treatments. However treatment 2 showed the significantly lowest (P<0.01) growth performance among the various treatments. The highest survival rate (92%) was also obtained with treatment 3. Tubifex proved to be the best larval feed in respect of growth and survival rate