Reconstruction and Performances of High-Entropy Alloy in ZIF-Derived Carbon Skeleton with Bifunctional Oxygen...

The bifunctional electrocatalysis of oxygen reduction reaction/oxygen evolution reaction (ORR/OER) with high activity and high stability requires multiple adsorption/reaction sites. Here, high-entropy alloy (HEA) nanoparticles embedded with relatively rich elements in a nitrogen-doped carbon skeleton as a bifunctional ORR/OER catalyst are proposed. More specifically, the nonmetal-derived carbon skeleton obtained by carbonizing ZIF-8 at high temperature is impregnated in different metal salt solutions, and then the FeCoNiCuMn HEA-embedded nitrogen-doped carbon electrocatalyst (FeCoNiCuMn/NC) is prepared by secondary pyrolysis. Due to the synergic effect between FeCoNiCuMn HEAs nanoparticles and nitrogen-doped carbon skeleton, the electrocatalyst with abundant and accessible active sites can provide great charge/mass transfer and thus shows high ORR and OER bifunctional electrocatalytic activation. The bifunctional electrocatalytic ORR/OER performance of FeCoNiCuMn/NC catalyst is further optimized by adjusting Mn content. In ORR tests, FeCoNiCuMn_1.0/NC catalyst displays the largest half-wave potential (E_1/2, 0.898 V), maximum limiting density of current (J_L, 5.22 mA cm^-2), and best stability. As for OER, FeCoNiCuMn_1.0/NC possesses a lower overpotential (η) of 300 mV at a current density of 10 mA cm^-2 and more durable stability than commercial RuO₂ (324 mV).