Comparative Study of the Structural Features and Electrochemical Properties of Nitrogen-Containing Multi-Walled Carbon Nanotubes after Ion-Beam Irradiation and Hydrochloric Acid Treatment
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2021-08-24 |
| Journal | Nanomaterials |
| Authors | П. М. Корусенко, С. Н. Несов, Anna Iurchenkova, Ekaterina O. Fedorovskaya, В. В. Болотов |
| Institutions | Novosibirsk State University, St Petersburg University |
| Citations | 32 |
| Analysis | Full AI Review Included |
Comparative Study of N-MWCNTs after Ion-Beam Irradiation and HCl Treatment
Section titled “Comparative Study of N-MWCNTs after Ion-Beam Irradiation and HCl Treatment”Executive Summary
Section titled “Executive Summary”This study investigates the structural and electrochemical modifications of Nitrogen-containing Multi-Walled Carbon Nanotubes (N-MWCNTs) following treatment with hydrochloric acid (HCl) or Argon ion-beam irradiation, focusing on maximizing specific capacitance for supercapacitor applications.
- Core Value Proposition: Treated N-MWCNTs achieved a specific capacitance of up to 27 F·g-1 at 5 mV·s-1, a significant increase compared to 13 F·g-1 for as-prepared nanotubes.
- Capacitance Mechanism: The enhanced performance is attributed to a high contribution of redox pseudocapacitance arising from electrochemically active pyridinic/pyrrolic nitrogen inclusions and Oxygen-Containing Functional Groups (OCFGs).
- HCl Treatment Effect: HCl successfully removed amorphous carbon layers, improving the structural ordering (crystallinity) of the N-MWCNTs (Raman ID/IG ratio decreased from 1.3 to 1.1).
- Ion Irradiation Effect: Ion bombardment induced significant structural defects (vacancy clusters, graphene rupture) and increased disorder (ID/IG ratio increased up to 3.0). This process selectively attached hydroxyl (C-OH) groups, reaching a maximum concentration of 17.2 at.%.
- Kinetic Differentiation: Analysis of cyclic voltammograms showed that redox reactions involving OCFGs are significantly faster (surface-based, dominant at high scan rates) than those involving pyridinic and pyrrolic nitrogen inclusions (slower, structural-based, dominant at low scan rates).
- Stability: Treated N-MWCNTs demonstrated stable characteristics after prolonged cycling, confirming the reversible nature of the redox reactions.
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Synthesis Temperature | 800 | °C | CCVD for N-MWCNTs |
| Electrolyte | 1 M H2SO4 | Aqueous Solution | Electrochemical testing |
| As-Prepared Specific Capacitance | 13 | F·g-1 | At 5 mV·s-1 scan rate |
| HCl Treated Specific Capacitance | 27 | F·g-1 | Maximum observed at 5 mV·s-1 |
| Ion Beam Energy | 5 | keV | Argon (Ar+) irradiation |
| Maximum Ion Fluence | 5.5 x 1016 | ion·cm-2 | Highest defect induction |
| As-Prepared ID/IG Ratio | 1.3 | Dimensionless | Raman spectroscopy |
| HCl Treated ID/IG Ratio | 1.1 | Dimensionless | Improved crystallinity |
| Max Irradiated ID/IG Ratio | 3.0 | Dimensionless | 5.5 x 1016 ion·cm-2 fluence |
| As-Prepared Graphene Domain Size (La) | 12.73 | nm | Calculated from Raman data |
| Max Irradiated Graphene Domain Size (La) | 5.52 | nm | 5.5 x 1016 ion·cm-2 fluence |
| Max C-OH Concentration | 17.2 | at.% | XPS C 1s, 5.5 x 1016 ion·cm-2 fluence |
| EDLC Contribution (HCl Treated) | ~70 | % | Ratio to total theoretical capacitance (CMax) |
| Redox Peak A1 (Pyridinic N) | 507 | mV | Charge curve (vs. Ag/AgCl) |
| Redox Peak C1 (OCFGs) | 599 | mV | Charge curve (vs. Ag/AgCl) |
Key Methodologies
Section titled “Key Methodologies”The study employed a combination of synthesis, modification, and advanced characterization techniques to analyze the N-MWCNTs.
1. N-MWCNT Synthesis (CCVD)
Section titled “1. N-MWCNT Synthesis (CCVD)”- Catalyst: Nickel nanopowder (derived from NiC2O4 decomposition).
- Precursor: Acetonitrile.
- Conditions: Flow-through gas-phase reactor, 800 °C, 1 hour duration.
2. Post-Synthesis Treatments
Section titled “2. Post-Synthesis Treatments”| Treatment Type | Parameters | Primary Structural Effect |
|---|---|---|
| Hydrochloric Acid (HCl) | 15% HCl solution, 60 min ultrasonic bath, 80 °C drying. | Removal of amorphous carbon; leaching of catalyst particles; slight increase in C-OH groups (4.5% to 6.3%). |
| Argon Ion-Beam Irradiation | 5 keV Ar+ ions, fluence up to 5.5 x 1016 ion·cm-2. | Formation of vacancy-type structural defects; rupture of graphene layers; selective attachment of hydroxyl groups (up to 17.2 at.%). |
3. Characterization and Electrochemical Analysis
Section titled “3. Characterization and Electrochemical Analysis”- Structural Analysis: High-Resolution Transmission Electron Microscopy (HRTEM) for morphology; Raman Spectroscopy for defectiveness (ID/IG ratio, La); X-ray Photoelectron Spectroscopy (XPS) for elemental composition and chemical states (N 1s, C 1s); Near-Edge X-ray Absorption Fine Structure (NEXAFS) for unoccupied electronic states.
- Electrode Preparation: N-MWCNT powder mixed with ethanol and F4D fluoroplastic binder, rolled into a dense black film (approx. 1 cm2).
- Electrochemical Testing: Three-electrode cell (N-MWCNT working electrode, Pt counter electrode, Ag/AgCl reference electrode) in 1M H2SO4.
- Cyclic Voltammetry (CV): Used to determine total specific capacitance and separate redox peaks associated with pyridinic N, pyrrolic N, and OCFGs.
- Electrochemical Impedance Spectroscopy (EIS): Used to study diffusion processes and separate contributions of Electric Double Layer Capacitance (EDLC) and Faradaic impedance (redox reactions).
Commercial Applications
Section titled “Commercial Applications”The controlled functionalization and enhanced electrochemical performance of N-MWCNTs demonstrated in this research are highly relevant for advanced energy and materials technologies.
- High-Performance Supercapacitors: The primary application, leveraging the high total specific capacitance (up to 27 F·g-1) achieved through significant pseudocapacitance contribution.
- Energy Storage Systems: Suitable for devices requiring high power density and long cycle stability, as confirmed by the reversible nature of the redox reactions observed during cycling tests.
- Catalyst Support Materials: The ability to selectively maximize C-OH groups via ion irradiation is critical for developing advanced composite catalysts. These hydroxyl groups serve as high-adhesion anchoring sites for metal oxide nanoparticles (e.g., MexOy@N-MWCNTs), enhancing performance in fuel cells or metal-air batteries.
- Advanced Nanoelectronics: The structurally modified nanotubes, particularly those with controlled defect density, can be utilized in flexible electronics and conductive composites requiring specific electronic band structures.
- Electrochemical Sensing: Functionalized N-MWCNTs offer high surface area and tailored chemical activity, making them excellent candidates for sensitive and selective electrochemical sensors in environmental or biological monitoring.
View Original Abstract
Using a set of microscopic, spectroscopic, and electrochemical methods, a detailed study of the interrelation between the structural and electrochemical properties of the as-prepared nitrogen-containing multi-walled carbon nanotubes (N-MWCNTs) and their modified derivatives is carried out. It was found that after treatment of nanotubes with hydrochloric acid, their structure is improved by removing amorphous carbon from the outer layers of N-MWCNTs. On the contrary, ion bombardment leads to the formation of vacancy-type structural defects both on the surface and in the bulk of N-MWCNTs. It is shown that the treated nanotubes have an increased specific capacitance (up to 27 F·g−1) compared to the as-prepared nanotubes (13 F·g−1). This is due to an increase in the redox capacitance. It is associated with the reversible Faraday reactions with the participation of electrochemically active pyridinic and pyrrolic nitrogen inclusions and oxygen-containing functional groups (OCFG). Based on the comparison between cyclic voltammograms of N-MWCNTs treated in HCl and with an ion beam, the peaks on these curves were separated and assigned to specific nitrogen inclusions and OCFGs. It is shown that the rate of redox reactions with the participation of OCFGs is significantly higher than that of reactions with nitrogen inclusions in the pyridinic and pyrrolic forms. Moreover, it was established that treatment of N-MWCNTs in HCl is accompanied by a significant increase in the activity of nitrogen centers, which, in turn, leads to an increase in the rate of redox reactions involving OCFGs. Due to the significant contribution of redox capacitance, the obtained results can be used to develop supercapacitors with increased total specific capacitance.
Tech Support
Section titled “Tech Support”Original Source
Section titled “Original Source”References
Section titled “References”- 2016 - Review on supercapacitors: Technologies and materials [Crossref]
- 2008 - Comparison Between Electrochemical Properties of Aligned Carbon Nanotube Array and Entangled Carbon Nanotube Electrodes [Crossref]
- 2019 - Carbon aerogels with oxygen-containing surface groups for use in supercapacitors [Crossref]
- 2016 - Supercapacitor performance of binder-free buckypapers from multiwall carbon nanotubes synthesized at different temperatures [Crossref]
- 2011 - The effect of carbonyl, carboxyl and hydroxyl groups on the capacitance of carbon nanotubes [Crossref]
- 2001 - Carbon materials for the electrochemical storage of energy in capacitors [Crossref]
- 2000 - Supercapacitor electrodes from multiwalled carbon nanotubes [Crossref]
- 2018 - Oxygen functional groups improve the energy storage performances of graphene electrochemical supercapacitors [Crossref]
- 2009 - Evaluation of mild acid oxidation treatments for MWCNT functionalization