Yang HLiu YLiu XWang XTian HWaterhouse GINKruger PETelfer SGMa S2024-12-022024-12-022022-05-17Yang H, Liu Y, Liu X, Wang X, Tian H, Waterhouse GIN, Kruger PE, Telfer SG, Ma S. (2022). Large-scale synthesis of N-doped carbon capsules supporting atomically dispersed iron for efficient oxygen reduction reaction electrocatalysis. eScience. 2. 2. (pp. 227-234).https://mro.massey.ac.nz/handle/10179/72147The large-scale synthesis of platinum-free electrocatalysts for the oxygen reduction reaction (ORR) remains a grand challenge. We report the large-scale production of stable and active ORR electrocatalysts based on iron, an earth-abundant element. A core–shell zeolitic imidazolate framework–tannic acid coordination polymer composite (ZIF-8@K-TA) was utilized as the catalyst precursor, which was transformed into iron atoms dispersed in hollow porous nitrogen-doped carbon capsules (H-Fe-Nx-C) through ion exchange and pyrolysis. H-Fe-Nx-C features site-isolated single-atom iron centers coordinated to nitrogen in graphitic layers, high levels of nitrogen doping, and high permeability to incoming gases. Benefiting from these characteristics, H-Fe-Nx-C demonstrated efficient electrocatalytic activity (E1/2 ​= ​0.92 ​V, vs. RHE) and stability towards the ORR in both alkaline and acidic media. In ORR performance, it surpassed the majority of recently reported Fe-N-C catalysts and the standard Pt/C catalyst. In addition, H-Fe-Nx-C showed outstanding tolerance to methanol.(c) The author/shttps://creativecommons.org/licenses/by-nc-nd/4.0/Metal single atomsHollow carbon capsulesOxygen reduction reactionMetal–organic frameworkElectrocatalysisJournal article10.1016/j.esci.2022.02.0052667-1417CC BY-NC-NDjournal-article227-234