Fe-doped Ni₃S₂@CoS_x nanoarrays derived from MOF as bifunctional electrocatalysts for efficient overall water-splitting

BACKGROUND: Fabricating high-performance bifunctional electrocatalysts remains challenging to promote the development of electrocatalytic water-splitting. RESULT: A heterostructure Fe-Ni₃S₂@CoS_x/NF was successfully synthesized using an interfacial engineering strategy. Benefiting from the strong synergistic effect between highly active cobalt sulfide (CoS_x) and iron-doped trinickel-disulfide (Ni₃S₂) (Fe-Ni₃S₂), Fe-Ni₃S₂@CoS_x/NF exhibited outstanding bifunctional performance, with low overpotentials of 77 and 217 mV for the cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER), respectively, at 10 mA cm⁻². CONCLUSION: The CoS_x nanoarrays and Fe-Ni₃S₂ nanosheets respectively served as HER and OER active centers. When Fe-Ni₃S₂@CoS_x/NF was used as both cathode and anode for overall water-splitting, a low voltage of 1.52 V was required to reach the current density of 10 mA cm⁻² with nearly 100% Faradic efficiency and outstanding durability.