High HER Activity Research Articles

Active guests in the MoS2/MoSe2 host lattice: efficient hydrogen evolution using few-layer alloys of MoS(2(1-x))Se(2x).

Few-layer transition metal dichalcogenide alloys based on molybdenum sulphoselenides [MoS2(1-x)Se2x] possess higher hydrogen evolution (HER) activity compared to pristine few-layer MoS2 and MoSe2. Variation of the sulphur or selenium content in the parent dichalcogenides reveals a systematic structure-activity relationship for different compositions of alloys, and it is found that the composition MoS1.0Se1.0 shows the highest HER activity amongst the catalysts studied. The tunable electronic structure of MoS2/MoSe2 upon Se/S incorporation probably assists in the realization of high HER activity.

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

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 3AlF 6–La 2O 3–Al 2O 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.

Preparation of the composite LaNi 3.7Al 1.3/Ni–S–Co alloy film and its HER activity in alkaline medium

The composite LaNi 3.7Al 1.3/Ni–S–Co alloy film was prepared by molten salt electrolysis and aquatic electrodeposition orderly. With Na 3AlF 6–La 2O 3–Al 2O 3 (91:8:1) system as molten salt electrolyte, the LaNi 3.7Al 1.3 alloy film was obtained by galvanostatic electrolysis at 100 mA cm −2. The results showed that the La 3+ and Al 3+ ions could be co-reduced on the nickel cathode to form LaNi 3.7Al 1.3 film, i.e. La 3+ + 1.3Al 3+ + 6.9e + 3.7Ni = LaNi 3.7Al 1.3 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 LaNi 3.7Al 1.3/Ni–S–Co film ( η 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.

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

The composite LaNi x /Ni–S–Co film with considerable stability and high HER activity ( η 150 = 70 mV, 353 K) was obtained by molten salt electrolysis combined with aquatic electrodeposition. LaNi x film was prepared by galvanostatic electrolysis at 100 mA cm −2 under 1273 K. The results showed that the La 3+ ions could be reduced on the nickel cathode and the LaNi x film could form, i.e. La 3+ + 3e + xNi = LaNi x ( 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 LaNi x /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.