湖南大学费慧龙团队报道了同时提高Fe-N-C氧还原催化剂位点密度和转化频率的二合一策略。相关研究成果发表在2025年1月14日出版的《德国应用化学》。

位点密度和周转频率是决定铁氮碳（FeNC）催化剂氧还原活性的两个基本动力学指标。然而，在单一的FeNC催化剂中同时优化这两个参数仍然是一个巨大的挑战。

该文中，研究表明，通过一步化学气相沉积工艺用碘化铵（NH₄I）蒸气处理典型的FeNC催化剂，不仅可以通过原位释放的NH₃的蚀刻效应增加催化剂的表面积和孔隙率（从而增加活性位点的暴露），还可以通过掺入碳基质中的碘掺杂剂调节FeN₄部分的电子结构。

因此，NH₄I处理的FeNC-催化剂在2.15×10¹⁹位点g1的位点密度（与未处理的对应物相比增强了2倍）和3.71电子位点s1的翻转频率（增强了3倍）方面都具有很高的值，对应于原位亚硝酸盐剥离技术定测的12.78A g^-1的高质量活性。此外，该催化剂在碱中表现出优异的氧还原活性，半波电位（E_1/2）为0.924 V，在酸中表现出可接受的活性，E_1/2=0.795 V，在锌空气电池中具有249.1 mW cm^-2的优异功率密度。

附：英文原文

Title: A Two-in-One Strategy to Simultaneously Boost the Site Density and Turnover Frequency of Fe−N−C Oxygen Reduction Catalysts

Author: Jianbin Liu, Yao Liu, Bing Nan, Dashuai Wang, Christopher Allen, Zhichao Gong, Guanchao He, Kaixing Fu, Gonglan Ye, Huilong Fei

Issue&Volume: 2025-01-14

Abstract: Site density and turnover frequency are the two fundamental kinetic descriptors that determine the oxygen reduction activity of iron-nitrogen-carbon (FeNC) catalysts. However, it remains a grand challenge to simultaneously optimize these two parameters in a single FeNC catalyst. Here we show that treating a typical FeNC catalyst with ammonium iodine (NH4I) vapor via a one-step chemical vapor deposition process not only increases the surface area and porosity of the catalyst (and thus enhanced exposure of active sites) via the etching effect of the in-situ released NH3, but also regulates the electronic structure of the FeN4 moieties by the iodine dopants incorporated into the carbon matrix. As a result, the NH4I-treated FeNC catalyst possesses both high values in the site density of 2.15×1019 sites g1 (×2 enhancement compared to the untreated counterpart) and turnover frequency of 3.71 electrons site1 s1 (×3 enhancement) that correspond to a high mass activity of 12.78 A g1, as determined by in-situ nitrite stripping technique. Moreover, this catalyst exhibits an excellent oxygen reduction activity in base with a half-wave potential (E1/2) of 0.924 V and acceptable activity in acid with E1/2 = 0.795 V, and superior power density of 249.1 mW cm2 in zinc-air batteries.

DOI: 10.1002/anie.202425196

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202425196