A 3D multi-interface structure of coral-like Fe-Mo-S/Ni3S2@NF using for high-efficiency and stable overall water splitting

Rational interface designing of noble-metal-free electrocatalysts is vital for the enhancement of efficiency and durability towards overall water splitting. In this study, the optimal Fe-Mo-S/Ni3S2@NF with a coral-like microstructure and multiple interfaces is fabricated successfully by a facile one-step hydrothermal method. Systematic experiments, including X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and electrochemical impedance spectroscopy (EIS), verify that these multiple interfaces in Fe-Mo-S/Ni3S2@NF will promote charge transfer and yield abundant active sites, leading to a synergistic effect on electrocatalytic reactions. As a result, this electrode material exhibits high hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity. When employing Fe-Mo-S/Ni3S2@NF as a bifunctional electrode for overall water splitting, the integrated electrolysis device can achieve an extremely low cell voltage of 1.51 V at 20 mA cm−2 in alkaline solution, outperforming the noble Pt/C-IrO2 couple (1.8 V @20 mA cm−2), as well as exhibits remarkable durability. Additionally, the favourable contributions of the multi-interface toward HER and OER are deeply investigated by density functional theory (DFT) calculations. This study provides insights into the significance of coupling interfaces, and it also suggests a possible design for future electrolysis catalysts.