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<p>This study presents a sustainable and catalyst-free approach for the controlled oxidation of single-walled carbon nanotubes (SWCNTs) using aqueous hydrogen peroxide (H₂O₂) under ambient conditions. By systematically varying oxidant concentration, solution pH, and reaction time, the extent of oxidation, defect generation, and structural modification could be effectively regulated. Comprehensive characterization using Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and zeta-potential measurements was employed to investigate the resulting physicochemical changes. The results revealed progressive defect formation, increased structural disorder, nanotube shortening, and enhanced surface oxidation with increasing oxidation severity. Raman analysis demonstrated a strong dependence of the defect density (I<sub>D</sub>/I<sub>G</sub> ratio) on oxidation conditions, highlighting the synergistic influence of acidic pH and prolonged reaction time on nanotube modification. Colloidal characterization showed significantly improved dispersion stability, reduced aggregate size, and increasingly negative zeta-potential values following oxidation, indicating enhanced aqueous processability. Optimal oxidation conditions were identified at moderate H₂O₂ concentrations (10–15 wt%) and mildly acidic pH (3–5), where effective surface modification and improved colloidal stability were achieved while preserving much of the nanotube structure. Compared with conventional acid-based oxidation methods, the proposed approach eliminates highly corrosive reagents and external activation processes while maintaining operational simplicity, environmental compatibility, and scalability. The findings provide mechanistic insight into catalyst-free H₂O₂-mediated oxidation and establish a versatile platform for tailoring SWCNT structural, surface, and colloidal properties for applications in polymer nanocomposites, conductive coatings, energy-storage materials, sensing technologies, and environmental remediation.</p>

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Green and tunable oxidation of single-walled carbon nanotubes using aqueous hydrogen peroxide under catalyst-free conditions: Structural evolution, defect generation, and colloidal stability

  • 期刊论文

  • 发表日期：

    2026年7月21日

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  • Thi Sinh Vo,
  • Van Hoan Hoang,
  • Jungon Yu,
  • Trung Hoang,
  • Kyunghoon Kim

摘要

This study presents a sustainable and catalyst-free approach for the controlled oxidation of single-walled carbon nanotubes (SWCNTs) using aqueous hydrogen peroxide (H₂O₂) under ambient conditions. By systematically varying oxidant concentration, solution pH, and reaction time, the extent of oxidation, defect generation, and structural modification could be effectively regulated. Comprehensive characterization using Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and zeta-potential measurements was employed to investigate the resulting physicochemical changes. The results revealed progressive defect formation, increased structural disorder, nanotube shortening, and enhanced surface oxidation with increasing oxidation severity. Raman analysis demonstrated a strong dependence of the defect density (ID/IG ratio) on oxidation conditions, highlighting the synergistic influence of acidic pH and prolonged reaction time on nanotube modification. Colloidal characterization showed significantly improved dispersion stability, reduced aggregate size, and increasingly negative zeta-potential values following oxidation, indicating enhanced aqueous processability. Optimal oxidation conditions were identified at moderate H₂O₂ concentrations (10–15 wt%) and mildly acidic pH (3–5), where effective surface modification and improved colloidal stability were achieved while preserving much of the nanotube structure. Compared with conventional acid-based oxidation methods, the proposed approach eliminates highly corrosive reagents and external activation processes while maintaining operational simplicity, environmental compatibility, and scalability. The findings provide mechanistic insight into catalyst-free H₂O₂-mediated oxidation and establish a versatile platform for tailoring SWCNT structural, surface, and colloidal properties for applications in polymer nanocomposites, conductive coatings, energy-storage materials, sensing technologies, and environmental remediation.