Alkaline Water Oxidation Catalyzed by 3D Self-Supported Cr-Doped Ni₃N Nanosheet Arrays

The development of highly efficient, stable, and low-cost electrocatalysts for oxygen evolution reaction (OER) is crucial for enhancing the efficiency of water splitting, but it still remains a huge challenge. Herein, three-dimensional (3D) self-supported Cr-doped Ni 3 N (Cr–Ni 3 N) nanosheet arrays were synthesized successfully on the carbon cloth by the hydrothermal method and subsequent nitridation process. Cr–Ni 3 N displays a superior alkaline OER performance with a low overpotential of 290 mV at the current density of 50 mA cm –2, a small Tafel slope of 56 mV dec –1, and robust electrochemical stability, which is much better than those of bare Ni 3 N and commercial RuO 2 . The calculation of density functional theory reveals that electron-rich Cr atoms transfer electrons to electron-deficient Ni and N atoms, effectively adjust the surface electron configuration of the Cr–Ni 3 N catalyst, and optimize the H 2 O adsorption in the 1 M KOH solution during the OER process. Additionally, the partially oxidized Cr 6+ during the OER can optimize the electronic structure and enhance the stability of NiOOH active sites by the strong electron withdrawing ability. This work can provide a pathway to rationally design efficient transition metal nitride-based OER electrocatalysts.