Showing papers on "Overpotential published in 1972"

Kinetics of the Deposition of Inert Particles from Electrolytic Baths

Abstract: To explain the peculiarities shown by the codeposition of inert particles from electrolytic baths, a mechanism based on two successive adsorption steps is proposed. In the first step the particles are loosely adsorbed, and they are in equilibrium with the particles in suspension. In the second step the particles are irreversibly adsorbed. Making a few elementary hypotheses about the mechanism that governs the two steps it is possible to deduce a general expression relating the concentration of the embedded particles to the suspension concentration and the electrode overpotential. This relationship is verified experimentally.

On the Deposition and Dissolution of Zinc in Alkaline Solutions

Abstract: The zinc/KOH‐zincate electrode reaction was investigated under high purity conditions with galvanostatic and potentiostatic transient techniques in the 0.1–3.0M and 0.0001–0.5M zincate concentration range. The exchange current density was found to be between 8 and 370 mA/cm2, with 40 mV/decade anodic and 120 mV/decade cathodic nominal Tafel slopes; an overpotential range of ± 100 mV was covered. The cathodic reaction orders were 1 for zincate, and −1 for hydroxyl ions. A four‐step mechanism, consistent with the kinetic data, is suggested. It consists of four consecutive dissociation reactions of the zincate complex, with two of them incorporating a single electron charge transfer. The rate‐determining step is The mechanism of the anodic and cathodic reactions is the same. The transients indicate only double layer charging and charge transfer processes. No surface diffusion effects or intermediate build‐up was observed (no pseudocapacitance). A rationalization is given for the mechanism. The effect of zinc surface preparation is discussed.

Method for reducing (pseudo-) ohmic overpotential at gas-evolving electrodes

Abstract: A method for reducing overpotential at gas-evolving electrodes wherein the electrodes are in the form of fine wires having a diameter of from 2 to 10 thousandths of an inch and are spaced about .18 to .30 inch from each other.

Electrolytic hydrogen source

Abstract: CLOSED CONTROL CIRCUIT IS FORMED, THE ELECTROCHEMICALLY ACTIVE POROUS LAYER OF THE ELECTRODE BEING SEPARATED FROM SAID COVER LAYER THEREOF BY A CONNECTING INTERLAYER. 1. AN ELECTROLYTIC HYDROGEN SOURCE WITH A PORTIONAL GAS GENERATION CONTROL, COMPRISING, IN COMBINATION POROUS ELECTRODES MADE OF ELECTROCHEMICALLY ACTIVE POROUS LAYER OF MATERIAL OF WHICH HYDROPHILIC SURFACE HAS A LOW OVERPOTENTIAL FOR HYDROGEN GENERATION, AND OF A PHYSICALLY ACTIVE COVER LAYER OF HYDROPHILIC MATERIAL HAVING A HIGHER OVERPOTENTIAL FOR HYDROGEN GENERATION, THE POROUS ELECTRODES, INCLUDING A SUPPORT IN WHICH THEY ARE SECURED, CONSTITUTING, AFTER BEING WETTED WITH AN ELECTROLYTE, A PRESSURIZED VESSEL HAVING AN OUTLET AND ADAPTED TO CONTAIN AN ELECTROLYTE AND OPERATING UP TO A HYDROGEN OVERPRESSURE, WITH RESPECT TO THE PRESSURE ON THE LEVEL OF THE ELECTROLYTE EQUALLING $P=2$.COS A/R IN WHICH $ IS SURFACE TNESION OF THE ELECTROLYTE, A IS AN ANGLE OF WETTING THE MATERIAL OF ELECTRODE SURFACE AND R IS A RADIUS OF THE PORES IN THE COVER LAYER OF THE ELECTRODE; A PRESSURE GAUGE ADAPTED TO COMMUNICATE WITH THE OUTLET OF SAID PRESSURIZED VESSEL AND EQUIPPED WITH MEANS FOR SCANNING PROPORTIONAL DEVIATIONS FROM A PRESET HYDROGEN PRESSURE VALUE; AND AN ELECTROLYTE CURRENT CONTROLLING ELEMENT CONNECTED TO THE OUTLET OF SAID PRESSURE GAUGE, WHEREBY A COMPLETELY

Electrochemical behavior of the boron anode in aqueous solutions

Abstract: The electrochemical oxidation of p-type boron in 0.2 N NaNO3 solutions of pH 0.4 to 13.1 was studied by galvanostatic techniques. The capacitance of the electrode, Tafel slopes, and a limited analysis of reaction mechanisms are reported. The anodic dissolution in acid solution is a charge-transfer-limited one-electron reaction to form a monovalent species in the over-potential region of 0.25 to 0.70 V. The dissolution in basic solution is most probably a one-electron charge-transfer reaction from a monovalent to divalent species involving three hydroxyl ions. Open circuit potentials were mixed potentials, probably due to hydrogen formation at open circuit but not contributing to the electrochemical reaction at the applied overpotential. Exchange current, estimated by extrapolation of the Tafel line to the standard oxidation potential for the boron reaction, were of the order of 10 to the minus 6th power A/cm2 in acid solution and 10 to the minus 12th power A/cm2 in basic solution. The reaction order of the rate determining acidic and basic reactions was determined with regard to (H+) and (OH-). The level of illumination had no effect on the electrochemical behavior of the electrode.