Heterogeneous electrocatalyst of nanoscale Fe-based medium-entropy alloy and sulfide for oxygen evolution reaction

The construction of heterojunctions between non-noble-metal based compounds affords a scheme for accelerating the reaction kinetics of oxygen evolution reaction (OER) without using precious mental materials, which is extremely important but remains challenging. Herein, the heterogeneous structure between Fe 60 Co 10 Ni 10 Cr 10 Mn 10 medium-entropy alloy (MEA) and FeS 2 is developed by a mechanical alloying approach. The resulting MEA-30 wt%FeS 2 delivers a high OER activity with a low overpotential of 261.6 mV at 10 mA/cm 2 , along with Tafel slope of 52.7 mV/dec in 1.0 mol/L KOH solution, superior to the commercial RuO 2 . The combination of detailed characterization techniques and density functional theory (DFT) calculation reveals that the heterojunctions between Fe-based MEA and FeS 2 generates the synergistic effect on the activation and formation steps of OOH*, thus promoting the OER reaction kinetics. Furthermore, the abundant active sites provided by the reconstructions of MEA-30 wt%FeS 2 during OER process also contributes to the catalytic performance. This work greatly expands the application scope of medium-entropy materials and provides a new method for the fabrication of novel heterogeneous electrocatalyst of Fe-based MEA and FeS 2 .