The influence of H-absorption on the cathodic response of high area nickel electrodes in alkaline solutions

✍ Scribed by S.A.S. Machado; J. Tiengo; P. de Lima Neto; L.A. Avaca

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 427 KB
• Volume: 39
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(94)85161-1

✦ Synopsis

Anomalous low values of the Tafel slope and of its temperature dependence have been frequently reported for the hydrogen evolution reaction (her) in alkaline solutions on high area nickel and nickel alloy electrodes and are the subject of much controversy. A systematic investigation carried out in this laboratory using Ni and Ni-Co deposits with roughness factors of the order of lo3 have shown that slopes of 118mV dec-' at 25°C can be obtained in concentrated alkaline solutions by means of rapid data acquisition (4ms point-'). The measured values follow very closely the relationship 2.3 x 2RT/F in the 25-75°C temperature range. In contrast, slow measurements (2OOmsp&t-') resulted in slopes of 80mVdec-' or lower that were almost independent of temperature. Cyclic voltammetry of the electrode surface in the Ni(O)/Ni(II) region showed marked differences for the two experiments suggesting the participation of absorbed hydrogen and the formation of surface hydrides in parallel with the her at low current densities.