Preparation of the composite LaNi3.7Al1.3/Ni-S-Co alloy film and its HER activity in alkaline medium

The composite LaNi3.7Al1.3/Ni-S-Co alloy film was prepared by molten salt electrolysis and aquatic electrodeposition orderly. With Na3AlF6-La2O3-Al2O3 (91:8:1) system as molten salt electrolyte, the LaNi3.7Al1.3 alloy film was obtained by galvanostatic electrolysis at 100 mA cm(-2). The results showed that the La3+ and Al3+ ions could be co-reduced on the nickel cathode to form LaNi(3.7)A(1.3) film, i.e. La3+ + 1.3Al(3+) + 6.9e + 3.7Ni = LaNi3.7Al1.3 at c.a. -0.5 V, which is much lower than that of the theoretical decomposition potential of lanthanum and aluminum. With high HER activity, the composite LaNi3.7Al1.3/Ni-S-Co film (eta(150) = 65 mV, 353 K) could absorb large amount of H atoms, which would be oxidized and therefore effectively avoid the dissolution of the Ni-S-Co film under the state of open-circuit and consequently prolong the lifetime of the cathode. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.