Liu Jianbin, Liu Yao, Nan Bing, Wang Dashuai, Allen Christopher, Gong Zhichao, He Guanchao, Fu Kaixing, Ye Gonglan, Fei Huilong
State Key Laboratory for Chemo/Biosensing and Chemometrics, Advanced Catalytic Engineering Research Center of the Ministry of Education, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China.
Institute of Zhejiang University - Qu Zhou, Qu Zhou, 324000, China.
Angew Chem Int Ed Engl. 2025 Apr 1;64(14):e202425196. doi: 10.1002/anie.202425196. Epub 2025 Jan 22.
Site density (SD) and turnover frequency (TOF) are the two fundamental kinetic descriptors that determine the oxygen reduction activity of iron-nitrogen-carbon (Fe-N-C) catalysts that represent the most promising alternatives to precious and scarce platinum. However, it remains a grand challenge to simultaneously optimize these two parameters in a single Fe-N-C catalyst. Here we show that treating a typical Fe-N-C catalyst with ammonium iodine (NHI) 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 NH, but also regulates the electronic structure of the Fe-N-C moieties by the iodine dopants incorporated into the carbon matrix. As a result, the NHI-treated Fe-N-C catalyst possesses both high values in the SD of 2.15×10 sites g (×2 enhancement compared to the untreated counterpart) and TOF of 3.71 electrons site s (×3 enhancement) that correspond to a high mass activity of 12.78 A g, as determined by in situ nitrite stripping technique. Moreover, this catalyst exhibits an excellent oxygen reduction activity in base with a half-wave potential (E) of 0.924 V and acceptable activity in acid with E =0.795 V, and superior power density of 249.1 mW cm in a zinc-air battery.
位点密度（SD）和周转频率（TOF）是两个基本的动力学描述符，它们决定了铁 - 氮 - 碳（Fe-N-C）催化剂的氧还原活性，而Fe-N-C催化剂是珍贵且稀缺的铂最有前途的替代品。然而，在单一的Fe-N-C催化剂中同时优化这两个参数仍然是一个巨大的挑战。在这里，我们表明，通过一步化学气相沉积过程用碘化铵（NHI）蒸汽处理典型的Fe-N-C催化剂，不仅通过原位释放的NH的蚀刻作用增加了催化剂的表面积和孔隙率（从而增强了活性位点的暴露），而且通过掺入碳基质中的碘掺杂剂调节了Fe-N-C部分的电子结构。结果，经NHI处理的Fe-N-C催化剂在SD方面具有2.15×10个位点/克的高值（与未处理的对应物相比提高了2倍），在TOF方面具有3.71个电子/位点·秒的高值（提高了3倍），这对应于通过原位亚硝酸盐剥离技术测定的12.78 A/克的高质量活性。此外，该催化剂在碱性条件下表现出优异的氧还原活性，半波电位（E）为0.924 V，在酸性条件下具有可接受的活性，E = 0.795 V，并且在锌空气电池中具有249.1 mW/cm²的优异功率密度。
