Multi-site catalyst derived from Cr atoms-substituted CoFe nanoparticles for high-performance oxygen evolution activity

Developing high-performance, stable and low-cost oxygen evolution reaction (OER) catalysts are pivotal for electrochemical water splitting and rechargeable metal-air batteries. In this work, we report an OER catalyst comprising Cr-CoFe, CoFe, Co_5.47N and Fe₃O₄ sites embedded in nitrogen-doped graphene (denoted as CCF-1) that operates remarkably in alkaline water. This catalyst requires only 210/290 mV overpotential to generate current densities of 10/500 mA cm⁻² with small Tafel slope (39.1 mV dec⁻¹) which is much better than the state-of-the-art IrO₂ catalyst (310 mV @10 mAcm⁻² with Tafel slope of 74.8 mV dec⁻¹). This striking OER performance is ascribed to substituted Cr atoms in the host matrix which modulated the geometric site/electronic structure of the catalyst and brings the optimal binding energies for oxygen intermediate with increased charge/mass transfer process for the fast kinetics of the OER reactions. Furthermore, CCF-1 demonstrated excellent OER durability which maintains the stable performance during the 200 h chronoamperometry test in 1 M KOH solution. The high stability of CCF-1 is attributed to the physicochemical protection effect of N doped graphitic layers which prevents the alloy nanoparticles from dissolution/re‐deposition and aggregation during the prolonged OER operation.