Active sites engineering on FeNi alloy/Cr3C2 heterostructure for superior oxygen evolution activity

The introduced Cr3C2 phase into FeNi alloys suppress the thermal coarsening of alloy nanoparticles and induce the charge rearrangement around interface, thereby increasing the number of active sites and intrinsic activity of per sites, respectively. [Display omitted] 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–Cr3C2 heterostructure anchored on carbon sheets (FeNi–Cr3C2@C) was reported, which can effectively catalyze OER with swift kinetics and outstanding intrinsic activity. The introduced Cr3C2 phase not only serves as a support material but also effectively suppresses the thermal coarsening of FeNi alloy nanoparticle. The FeNi–Cr3C2@C displays a robust OER activity with a low overpotential of 283 mV at the current density of 10 mA cm−2, a high turnover frequency value of 1.69 s−1 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 Cr3C2 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 Cr3C2 for electrochemical catalytic reactions.