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539.2+544.6+546+66 (1) |
Proprietăţile şi structura sistemelor moleculare (224) |
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SM ISO690:2012 VERNICKAITE, E., TSYNTSARU, Natalia, CESIULIS, Henrikas. Electrodeposited iron-group metals alloys with W and Mo for alkaline hydrogen evolution reaction. In: Materials Science and Condensed Matter Physics, Ed. 9, 25-28 septembrie 2018, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2018, Ediția 9, p. 304. |
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Materials Science and Condensed Matter Physics Ediția 9, 2018 |
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Conferința "International Conference on Materials Science and Condensed Matter Physics" 9, Chișinău, Moldova, 25-28 septembrie 2018 | ||||||
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CZU: 539.2+544.6+546+66 | ||||||
Pag. 304-304 | ||||||
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In recent years water electrolysis industry is mainly focusing on improving the efficiency of hydrogen evolution reaction (HER) by the proper selection of electrode materials. In this context W and Mo alloys with iron-group metals, namely Co, Ni and Fe, are attracting extensive attention due to their enhanced catalytic activity towards HER [1], good corrosion resistance [2], increased hardness [3], thermal stability [4] and relatively low price. Though the insufficient studies of the relationship between the composition and catalytic activity of alloys based on refractory metals still limits the understanding of their application for hydrogen production. Accordingly, in this study W based alloys with iron group metals having 5, 20 and ~ 30 at.% of W have been prepared by electrodeposition technique under galvanostatic mode from citrate-borate electrolyte onto stainless steel substrate and evaluated for their possible application for HER in alkaline environment. The electrocatalytic activity of the prepared alloys was studied by linear scan voltammetry in 30 wt.% NaOH medium at temperatures ranging from 25 to 65°C. Extrapolation of the polarization curves obtained at different temperatures, in the coordinates lni - ΔE to value ΔE=0 makes it possible to determine the exchange current density, i0, that describes the ability of electrode to reduce hydrogen ions from the electrolyte. It was determined that the i0 values for W-based cathodes become higher with increasing of W content in the alloys and the highest catalytic activity has been found for 30 at.% of W (Table 1). A significant improvement of catalytic activity for all tested coatings with increasing of the temperature has been noticed. The electrocatalytic activity at 65°C is decreasing in the following order Co-31W>Ni-30W>Fe-32W (in at.%) (Table 1). In order to enhance the catalytic activity, the efforts to achieve the higher content of refractory metal in the alloys have been made. Thus, highly concentrated acetate electrolyte has been investigated as alternative electrolyte to citrate-borate. This bath allowed to deposit only 25 at.% of W, but up to ~50 at.% of Mo could be reached. Thus, among all investigated electrodes the Mo-rich alloys demonstrated the highest catalytic activity towards hydrogen evolution reaction (Table 2). |
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