Coaxial Ni3S2@CoMoS4/NiFeOOH nanorods for energy-saving water splitting and urea electrolysis

High efficiency and energy-saving electrochemical hydrogen production has always been a research challenge, mainly due to the limitation of the sluggish kinetics of anodic reactions. Excellent performance depends largely on the clever design of nano-architectures and smart hybridization of active components. It is also very important to establish the relationship between structure and performance of materials. Form perspectives of chemical composition and nanostructure, we developed a novel heterostructure of Ni3S2@CoMoS4/NiFeOOH coaxial nanorods on NF scaffold, in which the two-dimensional CoMoS4 nanoplates and ultrathin NiFeOOH nanosheets vertically coil around the Ni3S2 nanorods by hydrothermal reaction combined with electrodepostion process. Such hierarchical nanorods can provide the heterointerface with highly open surface, ensuring the maximization of synergistic interaction. This heterostructure results in prominent bifunctional activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline water electrolysis systems, and HER coupled with urea oxidation reaction in urea electrolysis devices. It exhibits very low cell voltages for alkaline water splitting (1.732 V) and urea electrolysis (1.660 V) to afford a current density of 100 mA cm−2 in the two-electrode system as well as excellent long-term stability. Our work provides a new construction for combining various active materials to competitive bifunctional electrocatalysts applied in energy-relative electrochemical devices.