Engineered Interfaces of Nickel–Iron Nitride and Cobalt Oxide on Nitrogen-Doped Carbon Nanoribbons: A Catalytic High-Efficiency Zone for Water Splitting

Abstract

Electrocatalytic energy conversions are vital for advancing clean energy technologies, enabling processes such as water electrolysis that rely on electrochemical redox reactions at catalyst surfaces. Transition metal nitrides (TMNs) are considered as promising electrode materials due to their abundance, low cost, and noble metal-like electronic structure. In this work, we have synthesized nickel iron nitride supported over nitrogen-doped carbon nanoribbons designated as NiFeN@CoOx/N-CNRs via a facile two-step process. This involves the hydrothermal fabrication of NiFe-LDH on ZIF-12-derived CoOx/N-CNRs, followed by nitridation. The as-obtained composite NiFeN@CoOx/N-CNRs serves as a competent bifunctional electrode, delivering a current density of 20 mA/cm² at a sufficiently low overpotential (η) of 233 mV for the oxygen evolution reaction (OER) and 75 mV for hydrogen evolution reaction (HER). Moreover, it demonstrated fast reaction kinetics, minimal resistance to charge transfer (R_ct), a large electrochemically active surface area, and outstanding stability in alkaline reaction conditions for both OER and HER. These enhancements are attributed to the formation of a heterointerface between NiFeN and CoOx/N-CNRs, which facilitates superior charge migration and exploits the unique electronic properties of bimetallic nitrides. The hierarchical structure of the LDH precursor and the incorporation of N-CNRs further enhance conductivity, contributing to improved overall performance. This study provides a significant approach for fabricating and optimizing TMNs to be used as bifunctional electrodes in industrial alkaline water electrolyzers.