Plasma-modified flower-like CuFe–Ni₃S₂/Nickel foam heterostructure as a robust bifunctional electrocatalyst for high-efficiency overall water splitting

Electrochemical water splitting is an attractive approach to producing zero-carbon hydrogen and is considered to be the core of developing a carbon-neutral economy. High-efficiency nonprecious electrocatalysts are required to lower the overpotential of both cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER). Here, a PA@CuFe-Ni₃S₂/NF electrocatalyst with flower-like nanosheets was fabricated by a successive hydrothermal and plasma-assisted method. Benefiting from the optimized electronic structure and increased exposure of active sites originated from CuFe doping and plasma treatment, the optimal PA@CuFe-Ni₃S₂/NF electrocatalyst shows a low overpotential of 125 mV and 147 mV at 10 mA cm −2 for alkaline HER and OER, respectively, which are among the best values for transition-metal-based catalysts reported to date. Most significantly, when used as a bifunctional electrocatalyst for overall water splitting, the optimal PA@CuFe-Ni₃S₂/NF requires only 1.575 V to reach the current density of 10 mA cm -2 , making PA@CuFe-Ni₃S₂/NF one of the most effective earth-abundant electrocatalysts for overall water splitting, with performance comparable to precious metal catalysts of Pt/C||RuO 2 . Therefore, this work offers a viable strategy for fabricating bifunctional water splitting electrocatalysts for the realistic large-scale production of zero-carbon hydrogen.