Porous single crystal microcubes of niobium nitride for highly efficient electrocatalysis

Abstract

Transition metal nitrides (TMNs) possess remarkable catalytic activity and excellent electrical conductivity, making them appealing candidates for electrocatalytic materials. In this study, we have utilized a lattice reconstruction strategy to synthesize porous single crystal (PSC) Nb₄N₅ by nitriding single crystal microcubes of NaNbO₃, with the goal of achieving superior electrocatalytic performance and stability. The resultant PSC Nb₄N₅ combines the advantages of single crystals and porous materials with an ordered structure and a significant specific surface area. The synergistic effect of porosity and structural coherence of the porous single crystals produces numerous unsaturated Nb–N coordination sites on the surface, providing abundant active sites for catalyzing the hydrogen evolution reaction (HER). PSC Nb₄N₅ exhibits outstanding performance in the HER, with an overpotential of only 71.86 mV at a current density of 10 mA cm⁻², and maintains its activity for 100 hours. The single crystal nature of PSC Nb₄N₅ substantially enhances the catalytic stability of the electrode due to the super stability of the single crystals. Our findings manifest that active materials with an elaborately devised porous structure can enhance the HER properties dramatically during the electrocatalytic process in terms of both activity and stability, providing a new strategy for improving the electrocatalytic properties of the active electrode.