1,343 research outputs found

    Studies in fundamental chemistry of fuel cell reactions Quarterly report, 1 Jan. - 31 Mar. 1970

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    Fuel cell studies on reversibility of organic reactions, oxygen dissolution reaction, and organic adsorption on zinc electrodes of silver zinc batterie

    Studies in fundamental chemistry of fuel cell reactions Quarterly report, 1 Apr. - 30 Jun. 1970

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    Oxygen dissolution reaction, activation energy values, and dendrite growth inhibition in fuel cell chemistr

    Studies of the fundamental chemistry, properties, and behavior of fuel cells semiannual progress report, 1 mar. - 30 sep. 1964

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    Chemical reactions, catalytic activity, and electrode behavior in fuel cell

    Studies in fundamental chemistry of fuel cell reactions Quarterly report, 1 Jul. - 30 Sep. 1969

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    Electrocatalysts, dendritic deposition of zinc from alkaline solution, reversibility of organic reactions with platinum and gold electrodes, ion adsorption, and related studies on fuel cell

    Electric Conductance of Rh Atomic Contacts under Electrochemical Potential Control

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    The electric conductance of Rh atomic contacts was investigated under the electrochemical potential control. The conductance histogram of Rh atomic contacts varied with the electrochemical potential. When the electrochemical potential of the contact was kept at Φ0\Phi_{0}= 0.1 V vs. Ag/AgCl (Rh potential), the conductance histogram did not show any features. At Φ0\Phi_{0}= -0.1 V (under potential deposited hydrogen potential), the conductance histogram showed a feature around 2.3 G0G_{0} (G0G_{0} =2e2/he^{2}/h), which agreed with the conductance value of a clean Rh atomic contact, which was observed in ultrahigh vacuum at low temperature. At Φ0\Phi_{0}= -0.25 V (over potential deposited hydrogen potential), the conductance histogram showed features around 0.3 and 1.0 G0G_{0}. The conductance behavior of the Rh atomic contact was discussed by comparing previously reported results of other metals, Au, Ag, Cu, Pt, Pd, Ni, Co, and Fe. The conductance behavior of the metal atomic contacts related with the strength of the interaction between hydrogen and metal surface.Comment: 5 pages, 4 figures, Phys. Rev. B, in press

    Transient electrophoretic current in a nonpolar solvent

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    The transient electric current of surfactants dissolved in a nonpolar solvent is investigated both experimentally and theoretically in the parallel-plate geometry. Due to a low concentration of free charges the cell can be completely polarized by an external voltage of several volts. In this state, all the charged micelles are compacted against the electrodes. After the voltage is set to zero the reverse current features a sharp discharge spike and a broad peak. This shape and its variation with the compacting voltage are reproduced in a one-dimensional drift-diffusion model. The model reveals the broad peak is formed by a competition between an increasing number of charges drifting back to the middle of the cell and a decreasing electric field that drives the motion. After complete polarization is achieved, the shape of the peak stops evolving with further increase of the compacting voltage. The spike-peak separation time grows logarithmically with the charge content in the bulk. The time peak is a useful measure of the micelle mobility. Time integration of the peak yields the total charge in the system. By measuring its variation with temperature, the activation energy of bulk charge generation has been found to be 0.126 eV.Comment: 7 pages, 5 figure

    Model of the meniscus of an ionic liquid ion source.

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    A simple model of the transfer of charge and ion evaporation in the meniscus of an ionic-liquid ion source working in the purely ionic regime is proposed on the basis of order-of-magnitude estimates which show that, in this regime, _i_ the flow in the meniscus is dominated by the viscosity of the liquid and is affected very little by the mass flux accompanying ion evaporation, and _ii_ the effect of the space charge around the evaporating surface is negligible and the evaporation current is controlled by the finite electrical conductivity of the liquid. The model predicts that a stationary meniscus of a very polar liquid undergoing ion evaporation is nearly hydrostatic and can exist only below a certain value of the applied electric field, at which the meniscus attains its maximum elongation but stays smooth. The electric current vs applied electric field characteristic displays a frozen regime of negligible ion evaporation at low fields and a conduction-controlled regime at higher fields, with a sharp transition between the two regimes owing to the high sensitivity of the ion evaporation rate to the electric field. A simplified treatment of the flow in the capillary or liquid layer through which liquid is delivered to the meniscus shows that the size of the meniscus decreases and the maximum attainable current increases when the feeding pressure is decreased, and that appropriate combinations of feeding pressure and pressure drop may lead to high maximum currents

    Electrochemical processing of solid waste

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    The investigation into electrolysis as a means of waste treatment and recycling on manned space missions is described. The electrochemical reactions of an artificial fecal waste mixture was examined. Waste electrolysis experiments were performed in a single compartment reactor, on platinum electrodes, to determine conditions likely to maximize the efficiency of oxidation of fecal waste material to CO2. The maximum current efficiencies for artificial fecal waste electrolysis to CO2 was found to be around 50 percent in the test apparatus. Experiments involving fecal waste oxidation on platinum indicates that electrodes with a higher overvoltage for oxygen evolution such as lead dioxide will give a larger effective potential range for organic oxidation reactions. An electrochemical packed column reactor was constructed with lead dioxide as electrode material. Preliminary experiments were performed using a packed-bed reactor and continuous flow techniques showing this system may be effective in complete oxidation of fecal material. The addition of redox mediator Ce(3+)/Ce(4+) enhances the oxidation process of biomass components. Scientific literature relevant to biomass and fecal waste electrolysis were reviewed

    Electrochemical incineration of wastes

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    The disposal of domestic organic waste in its raw state is a matter of increasing public concern. Earlier, it was regarded as permissible to reject wastes into the apparently infinite sink of the sea but, during the last 20 years, it has become clear that this is environmentally unacceptable. On the other hand, sewage farms and drainage systems for cities and for new housing developments are cumbersome and expensive to build and operate. New technology whereby waste is converted to acceptable chemicals and pollution-free gases at site is desirable. The problems posed by wastes are particularly demanding in space vehicles where it is desirable to utilize treatments that will convert wastes into chemicals that can be recycled. In this situation, the combustion of waste is undesirable due to the inevitable presence of oxides of nitrogen and carbon monoxide in the effluent gases. Here, in particular, electrochemical techniques offer several advantages including the low temperatures which may be used and the absence of any NO and CO in the evolved gases. Work done in this area was restricted to technological papers, and the present report is an attempt to give a more fundamental basis to the early stages of a potentially valuable technology
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