| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1282407 | International Journal of Hydrogen Energy | 2011 | 9 Pages |
Ag, Pd and Pt-modified alkaline leached NiCoZn composite coatings were prepared on a copper specimen by electrochemical technique. The chemical composition of layers before and after leaching as well as after noble metal modification was determined by energy dispersive X-ray spectroscopy (EDX). The surface morphologies of the composite coatings were examined with the help of scanning electron microscopy (SEM). The hydrogen evolution activity of the electrodes was studied in 1 M KOH solution. For this purpose, cathodic current-potential curves and electrochemical impedance spectroscopy (EIS) techniques were used. Furthermore, the change of hydrogen evolution activity of the electrodes as a function of operation time in alkaline solution was also investigated. Surface morphologies showed that the composite coatings prepared to have compact and porous surface. EDX analysis confirmed the presence of Ag, Pd and Pt metals over the NiCoZn layer. The co-deposition of nickel, cobalt and zinc on copper surface and subsequently alkaline leaching of zinc rendered cathode material very active in hydrogen evolution. The modification of alkaline leached NiCoZn ternary coating by deposition of small amounts of Ag, Pd and Pt can further enhance the hydrogen evolution performance of this Raney-type electrode when compared to NiCoZn individually. The order of hydrogen evolution activity of catalysts studied is Ni < NiCoZn < NiCoZn–Pd < NiCoZn–Ag < NiCoZn–Pt. The long-term electrolysis tests showed that the Pt-modified electrode has the better time stability than the others. The superiority of Pt-modified catalyst explained by well known intrinsic catalytic activity of Pt.
Graphical abstractThe alkaline leached NiCoZn ternary coating was modified by deposition of small amounts of Ag, Pd and Pt to enhance the hydrogen gas evolution activity of this Raney-type electrode.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► NiCoZn–M (M: Ag, Pd and Pt) coatings were prepared and characterized for the HER. ► The composite coatings have a compact and porous structure. ► The noble metal particles were distributed homogeneously over the NiCoZn layer. ► The deposition of noble metals can further enhance the HER activity of NiCoZn. ► The Pt-modified electrode has the highest HER activity and best time stability among the studied electrodes.
