High-density, high-activity and high-spin atomic Fe (Ⅲ) sites on ZIF-8-derived microporous carbon for efficient oxygen reduction reaction

Enhancing oxygen reduction reaction (ORR) efficiency relies heavily on designing non-noble metal single-atom catalysts (SACs) with high-density and high-activity sites. For efficient ORR, Fe single atoms are precisely regulated and embedded into porous concave carbon derived from ZIF-8 in this work. ORR performance is significantly improved by the catalyst's concave design and microporous features, which optimize mass transfer and expose more active sites. Furthermore, the high-density, high-activity, and high-spin Fe (III) sites inside the material help to explain the increased intrinsic activity of the catalyst. Due to its unique carrier structure and iron site coordination, this catalyst exhibits outstanding ORR activity in a 0.1 M KOH solution. Additionally, zinc-air batteries constructed with this catalyst display a maximum peak power density of 151 mW cm −2 and a high specific capacity of 818 mAh g Zn −1 , outperforming Pt/C-based systems. This study presents a method for precursor treatment to efficiently and conveniently synthesize microporous carbon-based ORR SACs, aiming to advance ORR catalyst design.