Bimetallic Co-Mo nitride nanosheet arrays as high-performance bifunctional electrocatalysts for overall water splitting

Developing non-precious metal electrocatalysts with high activity and stability are of great significance to achieve overall water splitting. In this work, cobalt-molybdenum nitride nanosheet arrays grown on Ni foam (CoMoNx NSAs/NF) were prepared via a facile hydrothermal and nitridation process. The resulting CoMoNx NSAs/NF not only has a specific large surface area and provides more active sites but also possesses good electrical conductivity, contributing to the fast reaction kinetics. Furthermore, the synergistic effect between Co2N and Mo2N cooperatively enhance the charge transfer, thus further improving the electrocatalytic activity. Benefiting from these merits, the optimal CoMoNx-500 NSAs/NF exhibits excellent activities for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with overpotentials of 91 and 231 mV at the current density of 10 mA cm−2, respectively. Moreover, the CoMoNx-500 NSAs/NF||CoMoNx-500 NSAs/NF couple requires a low cell voltage of 1.55 V at the current density of 10 mA cm−2, which is much superior to many other reported transition metal nitrides catalysts. This present work provides a reference for the design of bimetallic nitrides with superior electrocatalytic performance for overall water splitting.