Gao Lesen, Gao Xia, Jiang Peng, Zhang Cunyin, Guo Hui, Cheng Yuanhui
State Key Laboratory of Organic-Inorganic Composites, College of Chemical Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China.
Small. 2022 Feb;18(8):e2105892. doi: 10.1002/smll.202105892. Epub 2021 Dec 13.
Atomically dispersed iron embedded carbon is a promising bifunctional catalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), but its exposed iron sites must be increased. Herein, the authors propose a double steric hindrance strategy by using zeolitic imidazolate frameworks-8 as the first barrier skeleton and encapsulated phenylboronic acid as the second space obstruction to realize densely exposed atomic iron sites. Prepared PA@Z8-FeNC has the highest iron content (5.49 wt%) among reported transition-metal-based single-atom oxygen catalysts. Meanwhile, its concave surfaces, hollow structures, and hierarchical pores enable the high utilization rate of iron sites to 88.5 ± 4.5% and exposed active site density to 5.2 ± 0.3 × 10 sites g . Resultantly, PA@Z8-FeNC exhibits superior activity and stability to commercial Pt/C and IrO for the ORR and OER in half-cells and zinc-air flow batteries. This provides insight for developing densely and accessibly active sites in single-atom catalysts.
原子分散的铁嵌入碳是一种有前景的用于氧还原反应（ORR）和析氧反应（OER）的双功能催化剂，但其暴露的铁位点必须增加。在此，作者提出了一种双重空间位阻策略，通过使用沸石咪唑酯骨架-8作为第一屏障骨架和封装的苯硼酸作为第二空间阻碍，以实现密集暴露的原子铁位点。制备的PA@Z8-FeNC在已报道的过渡金属基单原子氧催化剂中具有最高的铁含量（5.49 wt%）。同时，其凹面、中空结构和分级孔隙使铁位点的利用率高达88.5 ± 4.5%，暴露的活性位点密度达到5.2 ± 0.3 × 10个位点/克。结果，PA@Z8-FeNC在半电池和锌空气流动电池中对ORR和OER表现出优于商业Pt/C和IrO的活性和稳定性。这为在单原子催化剂中开发密集且可及的活性位点提供了思路。
