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.

Automated summary

In this work, a one-step ammonia nitridation process was proposed to embed noble metal Ir nanoparticles into the Ni3N nanosheet structure. The Ir-Ni3N heterogeneous interface was established on the surface of the nickel foam substrate. The results showed that the IrOx/NiOOH heterogeneous interfaces formed after self-reconstruction played a significant role in promoting the oxygen evolution reaction, with an overpotential of only 273.3 mV at a current density of 10 mA cm-2. This work also demonstrated the stability and efficiency of Ir-Ni3N as an electrocatalyst for hydrogen evolution and overall water splitting.