Tailoring First Coordination Sphere of Dual-Metal Atom Sites Boosts Oxygen Reduction and Evolution Activities

It is important to tune the coordination configuration of dual-atom catalyst (DAC), especially in the first coordination sphere, to render high intrinsic catalytic activities for oxygen reduction/evolution reactions (ORR/OER). Herein, a type of atomically dispersed and boron-coordinated DAC structure, namely, FeN₄B-NiN₄B dual sites, is reported. In this structure, the incorporation of boron into the first coordination sphere of FeN₄/NiN₄ atomic sites regulates its geometry and electronic structure by forming “Fe-B-N” and “Ni-B-N” bridges. The FeN₄B-NiN₄B DAC exhibits much enhanced ORR and OER property compared to the FeN₄-NiN₄ counterparts. Density functional theory calculations reveal that the boron-induced charge transfer and asymmetric charge distributions of the central Fe/Ni atoms optimize the adsorption and desorption behavior of the ORR/OER intermediates and reduce the activation energy for the potential-determining step. Zinc-air batteries employing the FeN₄B-NiN₄B cathode exhibit a high maximum power density (236.9 mW cm⁻²) and stable cyclability up to 1100 h. The result illustrates the pivotal role of the first-coordination sphere of DACs in tuning the electrochemical energy conversion and storage activities.