MIIT Key Laboratory of Critical Materials, Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, P. R. China.
State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150090, P. R. China.
Small. 2023 Jun;19(22):e2300758. doi: 10.1002/smll.202300758. Epub 2023 Mar 3.
Fe single atoms and N co-doped carbon nanomaterials (Fe-N-C) are the most promising oxygen reduction reaction (ORR) catalysts to replace platinum group metals. However, high-activity Fe single-atom catalysts suffer from poor stability owing to the low graphitization degree. Here, an effective phase-transition strategy is reported to enhance the stability of Fe-N-C catalysts by inducing increased degree of graphitization and incorporation of Fe nanoparticles encapsulated by graphitic carbon layer without sacrificing activity. Remarkably, the resulted Fe@Fe-N-C catalysts achieved excellent ORR activity (E = 0.829 V) and stability (19 mV loss after 30K cycles) in acid media. Density functional theory (DFT) calculations agree with experimental phenomena that additional Fe nanoparticles not only favor to the activation of O by tailoring d-band center position but also inhibit the demetallization of Fe active center from FeN sites. This work provides a new insight into the rational design of highly efficient and durable Fe-N-C catalysts for ORR.
单原子铁和氮共掺杂碳纳米材料（Fe-N-C）是最有前途的氧还原反应（ORR）催化剂，可替代贵金属。然而，高活性的 Fe 单原子催化剂由于石墨化程度低而稳定性差。在此，报道了一种有效的相转变策略，通过诱导增加石墨化程度和包含被石墨碳层包裹的 Fe 纳米颗粒，在不牺牲活性的情况下提高 Fe-N-C 催化剂的稳定性。值得注意的是，所得的 Fe@Fe-N-C 催化剂在酸性介质中表现出优异的 ORR 活性（E = 0.829 V）和稳定性（30K 循环后仅损失 19 mV）。密度泛函理论（DFT）计算与实验现象一致，即额外的 Fe 纳米颗粒不仅有利于通过调整 d 带中心位置来激活 O，而且还抑制了 Fe 活性中心从 FeN 位的脱金属化。这项工作为设计高效、稳定的 ORR 用 Fe-N-C 催化剂提供了新的见解。
