N-doped carbon nanohorns filled with Fe nanoparticles (Fe-N-CNHs) were produced by one-step positive pressure-assisted arc discharge in the Ar and N₂ mixture. After oxidation treatments in air, Fe was converted into Fe₂O₃, and nanopores were opened on CNHs from 1 to 5 nm controlled by oxidation temperature. Fe-N-CNHs oxidized in O₂ at 550 °C (Fe₂O₃-N-CNH550ox) show 245 mV at 20 mA cm^–1, which is much smaller than that of the ones oxidized at 500 °C (Fe₂O₃-N-CNH500ox), contributing to the larger pore size on CNHs (3–5 nm vs 2–3 nm) and a larger number of nanopores caused by the enhanced sidewall nanopores. However, the stability of Fe₂O₃-N-CNH550ox becomes much poorer than that of Fe₂O₃-N-CNH500ox after 2000 cycles. The unique relationship between the overpotential and long-term stability can be explained by the consideration of the size of Fe₂O₃ nanoparticles and nanopores on CNHs. Furthermore, the stability for Fe₂O₃-N-CNH550ox can be rapidly increased after heat treatment in Ar for 1 h caused by shrinking the size of tip nanopores. Herein, we first reveal that the performance of OER is related to the nanopore size of carbon carriers and the catalyst of nanometal particles. The optimization of pore-opening conditions in carbon carriers can be achieved a superior electrocatalytic OER performance, including a low overpotential at high current density and long-term stability.

中文翻译：

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在填充有 Fe/Fe2O3 纳米颗粒的 N 掺杂碳纳米角上打开优化的纳米孔作为氧析出反应的高级电催化剂

在Ar和N ₂混合物中通过一步正压辅助电弧放电制备了填充有Fe纳米颗粒（Fe-N-CNHs）的N掺杂碳纳米角。在空气中氧化处理后，Fe转化为Fe ₂ O ₃，并在氧化温度控制下在CNHs上打开1至5nm的纳米孔。Fe-N- CNHs在 550 °C (Fe ₂ O ₃ -N-CNH550ox) 中在 O ₂中氧化，在 20 mA cm ^{–1 下}显示 245 mV，远小于在 500 °C (Fe ₂氧₃-N-CNH500ox），导致 CNH 上的孔径更大（3-5 nm 对 2-3 nm）和由增强的侧壁纳米孔引起的更多纳米孔。然而，Fe ₂ O ₃ -N-CNH550ox的稳定性在 2000 次循环后变得比 Fe ₂ O ₃ -N-CNH500ox差很多。过电位和长期稳定性之间的独特关系可以通过考虑 Fe ₂ O ₃纳米颗粒和 CNH 上纳米孔的尺寸来解释。此外，Fe ₂ O ₃的稳定性-N-CNH550ox 在 Ar 中热处理 1 小时后，由于尖端纳米孔的尺寸缩小，可以迅速增加。在此，我们首先揭示了 OER 的性能与碳载体的纳米孔径和纳米金属颗粒的催化剂有关。碳载体中开孔条件的优化可以实现优异的电催化 OER 性能，包括在高电流密度下的低过电位和长期稳定性。