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. Boron doping is introduced to the first coordination sphere of Fe and Ni atoms to induce the structural deformation and asymmetric charge distributions of FeN4B and NiN4B sites. The dual-atom catalytic activities are remarkably enhanced compared to FeN4-NiN4. Zinc-air batteries deliver a peak power density of 237 mW cm-2 and long-term cyclability up to 1100 h. image