Electrochemical evolution of hydrogen on composite La–Ni–Al/Ni–S alloy film in water electrolysis

Abstract The composite La–Ni–Al/Ni–S alloy film was obtained by molten salt electrolysis and aquatic electrodeposition in turn. The La–Ni–Al alloy film was prepared in Na 3 AlF 6 –La 2 O 3 –Al 2 O 3 molten salt electrolyte by galvanostatic electrolysis at 100 mA cm −2 . The results showed that La 3+ and Al 3+ ions could be co-reduced on the nickel cathode and form La–Ni–Al film 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 La–Ni–Al/Ni–S film ( η 150  = 70 mV, 353 K) could absorb large amount of H atoms. Instead of the dissolution of the Ni–S film, the absorbed H atoms would be oxidized under intermittent electrolysis effectively and prolong the lifetime of the cathode.