Nickel-Iron nitrides and alloy heterojunction with amorphous N-doped carbon Shell: High-efficiency synergistic electrocatalysts for oxygen evolution reaction

Transition metal nitrides have received a great deal of attention as highly efficient OER catalysts due to their excellent electrical conductivity, which grants them lower overpotential values than precious metal oxide catalysts (RuO2, IrO2, etc.). Herein, we report the characteristics of Nickel-Iron nitrides, alloy heterogeneous nanostructures (Ni2Fe2N, Ni2Fe2N/Ni3Fe, Ni3Fe/Ni2Fe2N), and amorphous N-doped carbon shells differing only in nitridation temperature. Heterogeneous Nickel-Iron nitrides and alloy with amorphous N-doped carbon shells showed superior OER performance such as a low overpotential value of 251 mV at current density of 10 mA/cm2, Tafel slope of 35.0 mV/dec, and great stability even after 24 h. Additionally, this study accurately identified that the heterogeneous nanostructure and amorphous N-doped carbon shell improve the catalytic properties and durability of the Nickel-Iron nitrides and alloy nanoparticles. The morphological control strategy used to produce the heterogeneous nanostructure and amorphous N-doped carbon shell can be applied to improve electrochemical properties or encapsulation in strong alkaline solution.