Heteromorphic NiCo₂S₄/Ni₃S₂/Ni Foam as a Self-Standing Electrode for Hydrogen Evolution Reaction in Alkaline Solution

Considerable works have been devoted on developing high-efficiency nonplatinum electrocatalysts for hydrogen evolution reaction (HER). Herein, 3D heteromorphic NiCo₂S₄/Ni₃S₂ nanosheets network has been constructed on Ni foam (denoted as NiCo₂S₄/Ni₃S₂/NF) serving as a self-standing electrocatalyst through directly thermal sulfurization of a single-source NiCo-layered double hydroxide precursor. The resultant NiCo₂S₄/Ni₃S₂/NF electrode exhibits outstanding electrocatalytic HER performance with an extremely low onset overpotential of 15 mV and long-term durability in alkaline solution. Such enhanced HER performance can be credited to (1) the massive exposed active sites provided by mixed transition metal chalcogenides (NiCo₂S₄ and Ni₃S₂), (2) the strong interfacial interaction at NiCo₂S₄/Ni₃S₂ heterojunction interfaces with the strengthened H binding, and (3) the porous highly conductive Ni foam substrate with accelerated electron transfer. This work opens up a new direction to fabricate effective and non-noble-metal electrodes for water splitting and hydrogen generation.