Active sites engineering on FeNi alloy/CrC heterostructure for superior oxygen evolution activity.

Exploring high active electrocatalysts for oxygen evolution reaction (OER) is of great significance for a sustainable hydrogen economy. The development of non-precious transition metals, with sufficient active sites and ample intrinsic activity, remains a challenge. Herein, a new type of FeNi-CrC heterostructure anchored on carbon sheets (FeNi-CrC@C) was reported, which can effectively catalyze OER with swift kinetics and outstanding intrinsic activity. The introduced CrC phase not only serves as a support material but also effectively suppresses the thermal coarsening of FeNi alloy nanoparticle. The FeNi-CrC@C displays a robust OER activity with a low overpotential of 283 mV at the current density of 10 mA cm, a high turnover frequency value of 1.69 s at the overpotential of 300 mV (10 times higher than that of FeNi@C) and good stability in alkaline media. Density functional theory calculations (DFT) calculations show that CrC can facilitate the generation of electron-rich region at the Ni site in FeNi alloys as an active site, exhibiting an optimized adsorption behavior toward oxygen intermediate species with regard to decreased thermodynamic energy barriers. Our work opens up a promising path to modulate the electrocatalytic active sites using inexpensive and durable CrC for electrochemical catalytic reactions.