Boosting the dynamic reconstitution of FeCu–N4 sites via doping of bimetal nanoparticles during oxygen electrocatalysis

Abstract

Dual metal atom catalysts with nitrogen coordination are emerging as promising materials that can be substituted for platinum group-based catalysts employed for the oxygen electroreduction reaction. Proper introduction of nanoparticles (NPs) in the presence of single atoms (SAs) to construct binuclear or multinuclear sites is conducive to tailoring the electronic configuration and further realizing moderate binding strength between catalytic sites and O-containing intermediates. In this work, a versatile route for synthesizing FeCu–N₄ sites with doping of small Fe and Cu bimetal nanoparticles co-encapsulated in nitrogen-doped porous carbon nanosheets (FeCu_SNP@FeCu_SA/NC) is provided for use as a bifunctional cathode catalyst in a zinc–air battery (ZAB). The experimental data and theoretical analysis indicate that the small Fe/Cu nanoparticles and FeCu SAs synergistically act to accelerate oxygen reduction reaction and oxygen evolution reaction activity under alkaline conditions. As a result, the obtained FeCu_SNP@FeCu_SA/NC displayed competitive half-wave potential (E_1/2 = 0.883 V vs. RHE) that is 36 and 15 mV higher than that of its Fe_SNP@Fe_SA/NC and Cu_SNP@Cu_SA/NC counterparts, respectively. In addition, the FeCu_SNP@FeCu_SA/NC-based ZAB exhibited a high specific discharge capacity of 808.8 mAh g⁻¹, maximum power density of 187.3 mW cm⁻² at 325.8 mA cm⁻², and excellent cycling stability at 10 mA cm⁻² (180 h).