Herein, Fe–N–C catalysts are prepared from surface functionalized carbon nanotubes (CNTs) in combination with iron acetate and phenanthroline. An improved performance and structural composition is obtained by surface functionalization of the CNTs with indazole or pyridine. Catalyst composition and morphology are characterized by transmission electron microscopy, N₂ sorption, photoelectron spectroscopy, and ⁵⁷Fe transmission Mössbauer spectroscopy. However, activity and selectivity toward oxygen reduction reaction are determined from rotating ring disc electrode (RRDE) experiments. The durability and stability are evaluated by accelerated stress tests (0.0–1.2 V) and differential electrochemical mass spectroscopy (DEMS), respectively. It is shown that surface functionalization with indazole enables the direct attachment of FeN₄ centers to CNTs so that no impurity species are detected and a high activity is achieved, that can be attributed to an improved turnover frequency and higher mass‐based site density. Even more striking is the excellent durability and stability of the realized catalyst. While these trends are well pronounced in RRDE and DEMS, challenges in the preparation of membrane electrode assemblies make the trend not as obvious in fuel cells (FCs).

中文翻译：

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表面功能化对燃料电池应用中Fe–N–C催化剂内在性能的影响

本文中，Fe–N–C催化剂是由表面功能化的碳纳米管（CNT）与乙酸铁和菲咯啉结合制成的。通过用吲唑或吡啶对CNT进行表面官能化可获得改善的性能和结构组成。催化剂的组成和形态通过透射电子显微镜，N ₂吸附，光电子能谱和⁵⁷表征。铁的透射Mössbauer光谱。但是，根据旋转环盘电极（RRDE）实验确定了对氧还原反应的活性和选择性。耐久性和稳定性分别通过加速应力测试（0.0–1.2 V）和差分电化学质谱（DEMS）进行评估。结果表明，使用吲唑进行表面官能化可直接连接FeN ₄中心集中在CNT上，因此没有检测到任何杂质物种，并实现了高活性，这可以归因于更高的周转频率和更高的基于质量的位点密度。更为引人注目的是所实现的催化剂的出色耐久性和稳定性。尽管这些趋势在RRDE和DEMS中非常明显，但在制备膜电极组件方面面临的挑战使该趋势在燃料电池（FC）中不那么明显。