Engineering Ir and Ni3N heterogeneous interfaces for promoted overall water splitting

The development of efficient and stable electrocatalysts is a necessary way to overcome the huge overpotential of hydrogen production from water splitting. In this work, a one-step ammonia nitridation process was proposed, in which noble metal Ir nanoparticles were directly embedded into the Ni3N nanosheet structure, and the Ir-Ni3N heterogeneous interface was established on the surface of the nickel foam substrate. X-ray photoelectron spectroscopy showed that the IrOx/NiOOH heterogeneous interfaces formed after the surface self-reconstruction played an important role in promoting the oxygen evolution reaction, and its over-potential was only 273.3 mV at the current density of 10 mA cm-2. Impressively, the nanosheet structure of Ir-Ni3N remained stable after 10 h of constant current oxidation. In addition, when Ir-Ni3N was used as the electrocatalyst for hydrogen evolution reaction at the current density of 10 mA cm-2, the overpotential was only 66.7 mV. As expected, when it was examined for overall water splitting, the Ir-Ni3N demonstrated a low voltage (1.49 V), outperforming most of the HER/OER bi-functional catalysts reported recently. This work will provide an important basis for the study of transition metal nitrides, especially in improving the stability of oxygen evolution reaction.