A highly efficient heterostructure nanorod bifunctional electrocatalyst for realizing enhanced overall water splitting at a large current density†

Exploring efficient, low cost and stable electrocatalysts working at large current densities is crucial for upgrading the current industrial electrochemical water splitting. Herein, a novel FeS₂/Fe–Ni₃S₂ heterostructure was successfully prepared via a simple one-step in situ hydrothermal vulcanization using F⁻ regulation engineering. The FeS₂/Fe–Ni₃S₂ heterostructure array exhibits low overpotentials for both the OER (180 mV @ 10 mA cm⁻² and 300 mV @ 1 A cm⁻²) and the HER (105 mV @ 10 mA cm⁻² and 344 mV @ 1 A cm⁻²) with high stability operating at 1 A cm⁻² for 1000 h. In addition, the water-splitting system only needs 1.5 V to reach 10 mA cm⁻² and shows prolonged stability of more than 1200 h at 1 A cm⁻². The DFT calculations show that the electrons redistribute at the interface and favor the chemisorption of hydrogen and oxygen-containing intermediates. This work highlights a novel, low cost and practical electrode for industrial electrochemical water splitting.