Metallic Intermediate Phase Inducing Morphological Transformation in Thermal Nitridation: NiFeN-Based Three-Dimensional Hierarchical Electrocatalyst for Water Splitting.

Transition-metal nitrides have attracted a great deal of interest as electrocatalysts for water splitting due to their super metallic performance, high efficiency, and good stability. Herein, we report a novel design of hierarchical electrocatalyst based on NiFeN, where the presence of carbon fiber cloth as a scaffold can effectively alleviate the aggregation of NiFeN nanostructure and form three-dimensional conducting networks to enlarge the surface area and simultaneously enhance the charge transfer. The composition and morphological variations of NiFe precursors during annealing in different atmospheres were investigated. Such NiFeN/CC hierarchical electrocatalyst shows much improved electrochemical properties for water splitting in terms of overpotentials (105 and 190 mV at 10 mA/cm for hydrogen evolution reaction and oxygen evolution reaction, respectively) and stability.