The development of
bifunctional electrocatalysts with high performance
for both hydrogen evolution reaction (HER) and oxygen evolution reaction
(OER) with earth-abundant elements is still a challenge in electrochemical
water splitting technology. Herein, we fabricated a free-standing
electrocatalyst in the form of vertically oriented Fe-doped Ni3S2 nanosheet array grown on three-dimensional (3D)
Ni foam (Fe-Ni3S2/NF), which presented a high
activity and durability for both HER and OER in alkaline media. On
the basis of systematic experiments and calculation, the Fe-doping
was evidenced to increase the electrochemical surface area, improve
the water adsorption ability, and optimize the hydrogen adsorption
energy of Ni3S2, which resulted in the enhancement
of HER activity on Fe-Ni3S2/NF. Moreover, metal
sites of Fe-Ni3S2/NF were proved to play a significant
role in the HER process. During the catalysis of OER, the formation
of Ni–Fe (oxy)hydroxide was observed on the near-surface section
of Fe-Ni3S2/NF, and the introduction of the
Fe element dramatically enhanced the OER activity of Ni3S2. The overall water splitting electrolyzer assembled
by Fe-Ni3S2/NF exhibited a low cell voltage
(1.54 V @ 10 mA cm–2) and a high durability in 1
M KOH. This work demonstrated a promising bifunctional electrocatalyst
for water electrolysis in alkaline media with potential application
in the future.
It is a great challenge to fabricate electrode with simultaneous high activity for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Herein, a high‐performance bifunctional electrode formed by vertically depositing a porous nanoplate array on the surface of nickel foam is provided, where the nanoplate is made up by the interconnection of trinary Ni–Fe–Mo suboxides and Ni nanoparticles. The amorphous Ni–Fe–Mo suboxide and its in situ transformed amorphous Ni–Fe–Mo (oxy)hydroxide acts as the main active species for HER and OER, respectively. The conductive network built by Ni nanoparticles provides rapid electron transfer to active sites. Moreover, the hydrophilic and aerophobic electrode surface together with the hierarchical pore structure facilitate mass transfer. The corresponding water electrolyzer demonstrates low cell voltage (1.50 V @ 10 mA cm−2 and 1.63 V @ 100 mA cm−2) with high durability at 500 mA cm−2 for at least 100 h in 1 m KOH.
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