Electrodeposited tungsten-rich Ni-W, Co-W and Fe-W cathodes for efficient hydrogen evolution in alkaline medium

Abstract

The search of active, stable and cost-effective non-noble electrocatalysts for hydrogen evolution reaction (HER) is essential for sustainable energy systems. In this study, the electrodeposited Ni-W, Co-W and Fe-W coatings having 5–30 at.% of W were examined as an alternative electrocatalysts for hydrogen evolution. The electrocatalytic efficiency of the electrodes was investigated on the basis of electrochemical data obtained from steady-state polarization technique in 30 wt% NaOH solution. It was found that with increasing of tungsten content in the deposits up to ∼30 at.% a crystal-to-ultra-nanocrystalline transition takes place and the crystal grain size decreases up to 2–4 nm. The high content of W leads to course-grained coatings. These morphological and structural changes showed remarkable impact on the catalytic activity. The maximum catalytic performance was obtained for ultra-nanocrystalline W coatings. Among them the Ni-29at.%W demonstrated the highest apparent exchange current density (ECD) at the room temperature, i.e. 0.55 mA cm−2, thus indicating more favorable hydrogen reduction. A significant improvement of catalytic activity of all tested cathodes with increasing the temperature of NaOH solution was noticed. Among investigated Co-33at.%W, Fe-30at.%W and Ni-29at.%W cathodes, the last one showed the best performance towards HER (ECD = 14.5 mA cm−2 at 65 °C).