Defects on carbon nanotubes (CNTs) can be used as active sites to promote the occurrence of catalytic reactions and improve the ability of catalysts. Although some progress has been made in the synthesis of defects on carbon nanotubes (CNTs), most of the defects are caused by acid etching or high-temperature pyrolysis of organics, which is detrimental to the environment, and the defects are uncontrollable. Herein, we report the eco-friendly and controllable synthesis of defective CNTs by reduction of CO₂ under cathodic polarization in Li₂CO₃-based molten salts. The defective degree of CNTs can be tuned by changing the applied electrolysis current. The results show that low current is beneficial for the synthesis of CNTs with more defect sites. The most defect-rich carbon nanotubes synthesized under 300 mA cm⁻² electrolysis (CNTs-B₂O₃-300) in a molten Li₂CO₃/B₂O₃ composite melt performed the best in the 2e⁻ oxygen reduction reaction (ORR) compared with CNTs-B₂O₃-400 and CNTs-B₂O₃-500 obtained under higher current density electrolysis. This work provides an alternative strategy for the design and synthesis of defect-rich carbon materials for catalysis and energy applications.

中文翻译：

---

电化学控制的 CO2 原位转化为有缺陷的碳纳米管，以提高 H2O2 的产量

碳纳米管（CNTs）上的缺陷可以作为活性位点，促进催化反应的发生，提高催化剂的能力。虽然在碳纳米管（CNTs）上的缺陷合成方面取得了一些进展，但大部分缺陷是由有机物的酸蚀刻或高温热解引起的，对环境有害，并且这些缺陷是不可控的。在此，我们报告了通过在 Li ₂ CO ₃阴极极化下还原 CO _{2 来}环保且可控地合成有缺陷的碳纳米管基熔盐。可以通过改变施加的电解电流来调整碳纳米管的缺陷程度。结果表明，低电流有利于具有更多缺陷位点的碳纳米管的合成。在熔融的 Li ₂ CO ₃ /B ₂ O ₃复合熔体中，在 300 mA cm ^-2电解（CNTs-B ₂ O ₃ -300）下合成的缺陷最丰富的碳纳米管在 2e ^-氧还原反应中表现最好（ ORR) 与 CNTs-B ₂ O ₃ -400 和 CNTs-B ₂ O _{3 相比}-500 在较高电流密度电解下获得。这项工作为设计和合成用于催化和能源应用的富含缺陷的碳材料提供了一种替代策略。