Preparation and electrochemical properties of composite LaNix/Ni–S–Co alloy film

The composite LaNix/Ni–S–Co film with considerable stability and high HER activity (η150 = 70 mV, 353 K) was obtained by molten salt electrolysis combined with aquatic electrodeposition. LaNix film was prepared by galvanostatic electrolysis at 100 mA cm−2 under 1273 K. The results showed that the La3+ ions could be reduced on the nickel cathode and the LaNix film could form, i.e. La3+ + 3e + xNi = LaNix (x = 5 or 3) at ca. −0.6 V, which is much lower than that of the decomposition potential of lanthanum, due to the strong depolarization effect of nickel. Furthermore, compared with the traditional amorphous Ni–S film, the composite LaNix/Ni–S–Co film could absorb large amount of H atoms, which would be oxidized and avoid the dissolution of the Ni–S–Co film under the state of open-circuit effectively and increase the HER activity.