Metal–Organic Framework-Derived Bimetallic FeNi Sulfide Nanostructures for Electrolysis of Water and Urea

The urea oxidation reaction (UOR) is considered as an intriguing substitution of the oxygen evolution reaction (OER) to couple the cathodic hydrogen evolution reaction (HER) to produce H 2 with reduced energy in recent years. For UOR and HER processes, it is the key to develop low-cost and high-performance bifunctional electrocatalysts. In this work, a series of metal–organic framework (MOF)-derived bimetallic FeNi-sulfides is successfully synthesized with specific nanoscale hollow cubic morphology by a bimetallic strategy, where different sulfuration times and treatment temperatures are discussed in detail. The results show that the optimal sulfuration time is 2 h under a treatment temperature of 400 °C. As-synthesized FeNiS 400 -2h exhibits the best electrocatalytic activity with very low overpotentials of 269 mV for OER, 264 mV for HER, and 1.43 V for UOR at a current density of 10 mA cm –2 . Particularly, the coupled FeNiS 400 -2h||Pt/C cell for UOR||HER only needs a significantly low cell voltage of 1.57 V at the current density of 10 mA cm –2, which has exhibited remarkable improvement over other related metal sulfides in previous reports. Therefore, this study provides a rational multifunctional electrode structural design strategy for electrocatalytic water and urea splitting with energy-saving H 2 production.