| Autor: |
Artem Sh. Shamsutdinov, Anatoliy B. Shein, Vladimir I. Kichigin |
| Rok vydání: |
2017 |
| Předmět: |
|
| Zdroj: |
Конденсированные среды и межфазные границы. 19:222 |
| ISSN: |
1606-867X |
| DOI: |
10.17308/kcmf.2017.19/195 |
| Popis: |
The kinetics of the hydrogen evolution reaction on nickel silicide NiSi (fabricated by Czochralski method) in solutions of 0.5M H2SO4 and 1М КОН has been studied by polarization measurements and electrochemical impedance spectroscopy. In an acid solution two Tafel slopes have been observed on the polarization curve for NiSi: the slope b is equal to 0.105 V/decade at E > -0.33 V (SHE) and b = 0.18 V/decade at E < -0.33 V. In an alkaline solution one linear region of the Tafel line has been observed, b = 0.13 V/decade. The exchange current density i0 is 4.45 x 10-6 A cm-2 and 4.2 x 10-6 A cm-2 in acidic and alkaline solution respectively. In an acidic solution the Nyquist plots consist of a single semicircle at not high cathodic polarizations and of two well-resolved capacitive arcs at higher cathodic polarizations. An equivalent circuit considering the hydrogen absorption reaction was used at high cathodic polarizations. In an alkaline solution the Nyquist plots consist of a single capacitive semicircle. The potential dependences of equivalent circuit elements R1, R2, C2 and time constant R2C2 have been discussed. The conclusion was made that hydrogen evolution on NiSi in a sulfuric acid solution proceeds via a two-route Volmer–Heyrovsky–Tafel mechanism (with hydrogen absorption reaction in parallel) and in an alkaline solution via the Volmer–Heyrovsky mechanism with unequal transfer coefficients for the steps. The obtained results show that the adsorbed atomic hydrogen on an NiSi electrode obeys the Langmuir isotherm in both solutions. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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