A carboxylate linker strategy mediated densely accessible Fe-N4 sites for enhancing oxygen electroreduction in Zn-air batteries

• Published in: Journal of colloid and interface science 2024-07, Vol.665, p.879-887
• Main Authors: Wang, Dan, Zha, Sujuan, Li, Yaqiang, Li, Xiaosong, Wang, Jibiao, Chu, Yuan, Mitsuzaki, Naotoshi, Chen, Zhidong
• Format: Article
• Language: English
• Subjects: Accessible Fe-N4 sites; Oxygen reduction reaction; Single-atom catalysts; Zn-air battery
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2024.03.188

[Display omitted] •A carboxylate linker strategy is proposed to construct atomically dispersed catalyst.•The OAc linker enhances the site density of accessible Fe-N4 sites in FeNCOAc.•The FeNCOAc catalyst shows superior performance in both acidic and alkaline media.•Excellent performance are obtained in both liquid and solid-state Zn-air batteries. Iron-nitrogen-carbon single-atom catalysts derived from zeolitic-imidazolate-framework-8 (ZIF-8) have presented its great potential for the oxygen reduction reaction (ORR) in Zn-air batteries (ZABs). However, due to insufficient active Fe-N sites, its ORR activity is inferior to Pt-based catalysts. Herein, a carboxylate (OAc) linker strategy is proposed to design a ZIF-8-derived FeNCOAc catalyst with abundant accessible Fe-N4 single-atom sites. Except that imidazole groups can coordinate with Fe ions, the OAc linker on the unsaturated coordination Zn nodes can anchor and coordinate with more Fe ions, resulting in a significant increase in Fe-N4 site density. Meanwhile, the corrosion of carbon skeleton by OAc oxidation during heat-treatment leads to improved porosity of catalyst. Benefitting from the highly dense Fe-N4 sites and hierarchical pores, the FeNCOAc endows superior performance in alkaline medium (E1/2 = 0.906 V), which is confirmed by density functional theory calculation results. Meanwhile, the assembled liquid ZAB delivers a favorable peak power density of 173.9 mW cm−2, and a high specific capacity of 770.9 mAh g−1 as well as outstanding durability. Besides, the solid-state ZAB also shows outstanding discharge performance.