We demonstrate that control of the defect level on carbon materials is effective for enhancing the oxygen reduction reaction (ORR) performance of nonprecious-metal catalysts. Vapor-grown carbon nanofiber (VGCNF) with high crystallinity and high electronic conductivity was chosen as the substrate of our ORR catalysts. To induce defects on the VGCNF, it was subjected to ball-milling for various controlled times, yielding BM x -VGCNF ( x represents the ball-milling time, 0-6 h). The defect level introduced on the VGCNF was effectively regulated by controlling the ball-milling time. Although the density of defect sites increased with increasing ball-milling time, the surface area was high-est in BM2-VGCNF. Nonprecious-metal ORR catalysts (BM x -Fe-VGCNF) were prepared by NH3 pyrolysis of Fe-ion-adsorbed BM x -VGCNF. The ball-milling of VGCNF was effective to introduce nitrogen onto the catalyst. In particular, the controlled ball-milling was important to generate highly active sites on the catalyst surface. Among the catalysts studied, BM2-Fe-VGCNF exhibited the best ORR performance, which was 2.5-times greater than that of BM x -Fe-VGCNF ( x =4, 6).

中文翻译：

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通过球磨进行氧还原反应的缺陷控制 Fe-N 掺杂碳纳米纤维

我们证明控制碳材料的缺陷水平对于提高非贵金属催化剂的氧还原反应（ORR）性能是有效的。选择具有高结晶度和高电导率的气相生长碳纳米纤维 (VGCNF) 作为我们 ORR 催化剂的基材。为了在 VGCNF 上引起缺陷，对其进行各种受控时间的球磨，产生 BM x -VGCNF（x 代表球磨时间，0-6 小时）。通过控制球磨时间有效地调节了 VGCNF 上引入的缺陷水平。尽管缺陷位点的密度随着球磨时间的增加而增加，但表面积在 BM2-VGCNF 中最高。非贵金属 ORR 催化剂 (BM x -Fe-VGCNF) 通过 NH3 热解 Fe 离子吸附的 BM x -VGCNF 制备。VGCNF 的球磨可有效地将氮引入催化剂。特别是，受控球磨对于在催化剂表面产生高活性位点很重要。在所研究的催化剂中，BM2-Fe-VGCNF 表现出最好的 ORR 性能，是 BM x -Fe-VGCNF ( x = 4, 6) 的 2.5 倍。