Composition-Tunable Co<sub>3–<i>x</i></sub>Fe<sub><i>x</i></sub>Mo<sub>3</sub>N Electrocatalysts for the Oxygen Evolution Reaction
Chengzhi Zhong, Jiaxi Zhang, Longhai Zhang, Yuanhua Tu, Huiyu Song, Li Du, Zhiming Cui
Abstract
The sluggish OER kinetics necessitates the development of highly active and durable electrocatalysts; however, an ideal alternative to expensive Ir/Ru-based and poorly conductive metal-oxide-based catalysts is absent. Herein, we demonstrate the class of nitrides prototype of Co 3– x Fe x Mo 3 N (0 ≤ x ≤ 3). These nitrides are cost-effective and highly conductive and have favorable composition flexibility. The optimized Co 2.5 Fe 0.5 Mo 3 N shows a mere overpotential of 218 mV at 10 mA cm geo –2 and a robust durability at 100 mA cm geo –2 over a 90-h measurement. Impressively, the water electrolyzer of Pt/C∥Co 2.5 Fe 0.5 Mo 3 N only requires a cell voltage of 1.52 V to afford 10 mA cm geo –2 . XPS spectra and DFT calculation reveal that the partial Fe substitution not only increases the content of the active Co 3+ species of Co 2.5 Fe 0.5 Mo 3 N but also upshifts the d band center of the Co site toward the Fermi level, which leads to the lower absorption energy of oxygen intermediates and hence substantially promotes the OER activity.