Electrochemical Study of the Nickel-Hydrogen System

Szklarska‐Śmiałowska, Z.; Smialowski, M.

doi:10.1149/1.2425783

Cited by 57 publications

(39 citation statements)

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“…However, this disagrees with the results of [10], according to which the dissociation rate constant of hydride NiH 0.4 (estimated from transients of a hydrogen volume generated by nickel hydride at E c in deaerated acidic solutions) is constant and begins to increase at pH > 6.…”

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confidence: 98%

Corrosion of Hydrides of Nickel and Cu30Ni Alloy in Oxygen Containing Solutions

2005

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yan, Sirota, Pchel'nikov. As was shown earlier [1], nickel hydride quickly decomposes at its open-circuit potential E c in an oxygen-saturated sulfuric-acid solution (1 N H 2 SO 4 ), which is accompanied by hydrogen evolution. As a result, attempts to determine the corrosion rate of nickel hydride by using the oxygen compensation (OC) method has failed.In this work, we study the corrosion behavior of the nickel and Cu30Ni alloy hydrides in oxygen-saturated alkaline, neutral, and weakly acidic solutions.Corrosion tests were carried out in oxygen atmosphere by the OC method [2, 3] in a modernized cell with thermal control [4] and additionally by spectrophotometry (SF) [5].We used samples of 1-3 cm 2 surface areas and the following solutions: 1 N NaOH; 0.01 N NaOH + 0.16 N Na 2 SO 4 ; 0.16 N Na 2 SO 4 (pH 7); 10 -3 N H 2 SO 4 + 0.16 N Na 2 SO 4 at 20 ° C.The essence of OC method lies in compensation of oxygen consumed in corrosion by oxygen obtained in electrolyzer. The corrosion rate is estimated from the charge ∆ Q consumed in the electrolyzer for a time ∆ twhere S is the surface area of the sample, m 2 .Hydrides of nickel and alloy were synthesized by hydrogenation (HG) of samples during cathodic polarization in 1 N H 2 SO 4 solution containing 0.2 g/l thiourea ( i HG = 170 A/m 2 , t HG = 0.5-2 h) in a separate cell, i.e., under the conditions of hydride formation, according to [6]. Then, the samples were quickly (10-30 s) washed in twice distilled water, transferred to the working chamber of the OC cell, in which time variations of i c ∆Q/∆tS Ä/m 2 ( ), = E c and the charge Q consumed in the corrosion process were measured.Being placed in the OC cell, nickel hydride immediately begins to uptake oxygen (Fig. 1). Therewith, upon longer nickel hydrogenation, and, correspondingly, for thicker hydride layers, one needs greater charges in order to replenish oxygen consumed in hydride corrosion (curves 1 and 2 ). The corrosion rate i c calculated from the slope of Q vs. t curves (Fig. 2a, curves 1 and 2 ) decreases in time and reaches the value observed for corrosion of original nickel ( i c < 0.1 A/m 2 ). In the process, at first, E c decreases insignificantly, passes a flat Abstract -Corrosion behavior of nickel hydride is studied in alkaline, neutral, and weakly acidic oxygen-containing solutions by compensating oxygen consumed in corrosion and spectrophotometric analysis of solution for nickel. It is shown that in the course of nickel hydride corrosion in alkaline solutions, oxygen is consumed solely in its interaction with hydrogen formed at hydride decomposition, while nickel remains at the surface. It is concluded that, in a pH range from 7 to 14, hydrogen oxidation is limited by its solid-phase diffusion, whereas the rate of nickel hydride decomposition is pH-independent. The difference in the corrosion behavior of the original alloy and its hydride is attributed to the fact that the original alloy evolves copper ions, whereas the hydride evolves hydrogen. 9 8 7 6 5 4 3 2 1 0 50 100 150 200 t , min Q , C 1 2...

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Corrosion of Hydrides of Nickel and Cu30Ni Alloy in Oxygen Containing Solutions

2005

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“…Hydrogen can penetrate interstitially into the nickel crystals during cathodic polarization in 0.5 M H2SO 4 at a sufficiently high current density [8]. This can ultimately lead to nickel hydride formation.…”

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confidence: 99%

Absorption of hydrogen in reduced nickel oxide

Visscher

Barendrecht

1980

J Appl Electrochem

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“…In addition, the effects of KOH metallic impurities and the proposed relationship between signal decay and hydrogen electrosorption during hydrogen evolution (8,11,(14)(15)(16) were investigated at 343 K. Impedance measurements around the reversible hydrogen electrode potential in the low-frequency region (17) and analysis of Tafel lines in the low cathodic overpotential range were performed in 30 w/o KOH.…”

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Hydrogen Evolution and Interface Phenomena on a Nickel Cathode in 30 w/o KOH : I . Kinetics Parameters and Electrode Impedance Between 303 and 363 K

Huot

1989

J. Electrochem. Soc.

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The hydrogen evolution reaction (HER) is investigated on a nickel cathode in 30 weight percent (w/o) KOH containing KOH metallic impurities. It is shown that the hydrogen evolution mechanism does not vary substantially between 303 and 363 K and that the apparent heat of activation is 21 kJ tool-1. Reduction of the ferric impurity influences the log(i)-E curves for the HER at low cathodic overpotentials and at temperatures higher than 323 K. Impedance measurements during water electrolysis confirm the limited influence of thermal energy on charge transfer kinetics and underline the effect of the hydrogen bubble layer on the accessible surface. A pseudocapacitive effect observed at low cathodic overpotentials and at anodic overpotentials is tentatively explained by hydrogen electrosorption and nickel oxidation.

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Electrochemical Study of the Nickel-Hydrogen System

Cited by 57 publications

References 1 publication

Corrosion of Hydrides of Nickel and Cu30Ni Alloy in Oxygen Containing Solutions

Corrosion of Hydrides of Nickel and Cu30Ni Alloy in Oxygen Containing Solutions

Absorption of hydrogen in reduced nickel oxide

Hydrogen Evolution and Interface Phenomena on a Nickel Cathode in 30 w/o KOH : I . Kinetics Parameters and Electrode Impedance Between 303 and 363 K

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