X-ray absorption near-edge structure and photoelectron spectroscopy of single-walled carbon nanotubes modified by a HBr solution

Zhong, Jun; Li, Song; Wu, Ziyu; Xie, Sishen; Abbas, Mamatimin; Ibrahim, Kurash; Huang, Qian

doi:10.1016/j.carbon.2005.10.029

Cited by 38 publications

(28 citation statements)

References 36 publications

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“…In general, A and C peaks are assigned to the transition from C 1s core to CC π* and σ* states, respectively. The B peak is assigned to free‐electron‐like interlayer states in graphite or carbon nanotubes . As can be seen from the NEXAFS spectra in Figure b, the presence of a pronounced B peak indicates structural changes with the increased sp 3 ‐like structure, while the decreased intensity of A peaks demonstrates a weakening of the CC π* network.…”

Section: Resultsmentioning

confidence: 94%

Defect Engineering in Two Common Types of Dielectric Materials for Electromagnetic Absorption Applications

Quan

Shi

Ong

et al. 2019

Adv Funct Materials

514

162

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(1 of 10)Dielectric materials are greatly desired for electromagnetic absorption applications. Lots of research shows that conduction loss and polarization are two of the most important factors determining complex permittivity. However, the detailed dissipation mechanisms for the improved microwave absorption performance are often based on semiempirical rules, lacking practical data relationships between conduction loss/polarization and dielectric behaviors. Here, a strategy of introducing point defects is used to understand such underlying relationships, where polarizability and conductivity are adjustable by manipulating oxygen deficiency or heteroatoms. Based on first principles calculations and the applied oxygendeficient strategy, dielectric polarization is shown to be dominant in determining the permittivity behaviors in semiconductors. Meanwhile, the presented nitrogen doping strategy shows that conduction loss is dominant in determining the permittivity behavior in graphitized carbon materials. The validity of the methods for using point defects to explore the underlying relations between conduction loss/polarization and dielectric behaviors in semiconductor and graphitized carbon are demonstrated for the first time, which are of great importance in optimizing the microwave absorption performance by defect engineering and electronic structure tailoring.

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Section: Resultsmentioning

confidence: 94%

Defect Engineering in Two Common Types of Dielectric Materials for Electromagnetic Absorption Applications

Quan

Shi

Ong

et al. 2019

Adv Funct Materials

514

162

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“…X‐ray near‐edge structure (XANES) spectroscopy is an effective way to investigate the structure and composition changes. In the C 1s XANES spectrum, the distinguishable π* feature at ≈286 eV corresponding to the sp 2 bonding configuration, and feature at 293 eV is attributed to the transition of exciton from core level to σ* states . The presence of peak at 288.5 eV between π* and σ* resonances corresponds to the structure changes due to the increased sp 3 ‐like structure, with a minor contribution may come from CH at the edge or defective sites .…”

Section: Resultsmentioning

confidence: 99%

“…In the C 1s XANES spectrum, the distinguishable π* feature at ≈286 eV corresponding to the sp 2 bonding configuration, and feature at 293 eV is attributed to the transition of exciton from core level to σ* states . The presence of peak at 288.5 eV between π* and σ* resonances corresponds to the structure changes due to the increased sp 3 ‐like structure, with a minor contribution may come from CH at the edge or defective sites . With the increase of ball‐milling time, the obviously enhanced intensity of peak at 288.5 eV indicates the increased defect content, which is in well accordance with the XPS results.…”

Section: Resultsmentioning

confidence: 99%

Boosting the Electrical Double‐Layer Capacitance of Graphene by Self‐Doped Defects through Ball‐Milling

Dong

Zhang

et al. 2019

Adv Funct Materials

286

156

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Improving the capacitance of carbon materials for supercapacitors without sacrificing their rate performance, especially volumetric capacitance at high mass loadings, is a big challenge because of the limited assessable surface area and sluggish electrochemical kinetics of the pseudocapacitive reactions. Here, it is demonstrated that "self-doping" defects in carbon materials can contribute to additional capacitance with an electrical double-layer behavior, thus promoting a significant increase in the specific capacitance. As an exemplification, a novel defect-enriched graphene block with a low specific surface area of 29.7 m 2 g −1 and high packing density of 0.917 g cm −3 performs high gravimetric, volumetric, and areal capacitances of 235 F g −1 , 215 F cm −3 , and 3.95 F cm −2 (mass loading of 22 mg cm −2 ) at 1 A g −1 , respectively, as well as outstanding rate performance. The resulting specific areal capacitance reaches an ultrahigh value of 7.91 F m −2 including a "self-doping" defect contribution of 4.81 F m −2 , which is dramatically higher than the theoretical capacitance of graphene (0.21 F m −2 ) and most of the reported carbon-based materials. Therefore, the defect engineering route broadens the avenue to further improve the capacitive performance of carbon materials, especially for compact energy storage under limited surface areas.

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“…In a recent report XANES was demonstrated as a very useful tool to probe the surface chemistry, degree of order, molecular orientation, and electronic structure of carbon nanotubes . Even though the origin of various XANES features was complicated, the spectral features related to different bonding states or functional groups in carbon nanomaterials have been widely discussed . Recently, XANES has been also shown to be very useful to probe the electronic structure of graphene for various applications …”

Section: Introductionmentioning

confidence: 99%

Synchrotron Soft X‐ray Absorption Spectroscopy Study of Carbon and Silicon Nanostructures for Energy Applications

et al. 2014

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Carbon and silicon materials are two of the most important materials involved in the history of the science and technology development. In the last two decades, C and Si nanoscale materials, e.g., carbon nanotubes, graphene, and silicon nanowires, and quantum dots, have also emerged as the most interesting nanomaterials in nanoscience and nanotechnology for their myriad promising applications such as for electronics, sensors, biotechnology, etc. In particular, carbon and silicon nanostructures are being utilized in energy-related applications such as catalysis, batteries, solar cells, etc., with significant advances. Understanding of the nature of surface and electronic structures of nanostructures plays a key role in the development and improvement of energy conversion and storage nanosystems. Synchrotron soft X-ray absorption spectroscopy (XAS) and related techniques, such as X-ray emission spectroscopy (XES) and scanning transmission X-ray microscopy (STXM), show unique capability in revealing the surface and electronic structures of C and Si nanomaterials. In this review, XAS is demonstrated as a powerful technique for probing chemical bonding, the electronic structure, and the surface chemistry of carbon and silicon nanomaterials, which can greatly enhance the fundamental understanding and also applicability of these nanomaterials in energy applications. The focus is on the unique advantages of XAS as a complementary tool to conventional microscopy and spectroscopy for effectively providing chemical and structural information about carbon and silicon nanostructures. The employment of XAS for in situ, real-time study of property evolution of C and Si nanostructures to elucidate the mechanisms in energy conversion or storage processes is also discussed.

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X-ray absorption near-edge structure and photoelectron spectroscopy of single-walled carbon nanotubes modified by a HBr solution

Cited by 38 publications

References 36 publications

Defect Engineering in Two Common Types of Dielectric Materials for Electromagnetic Absorption Applications

Defect Engineering in Two Common Types of Dielectric Materials for Electromagnetic Absorption Applications

Boosting the Electrical Double‐Layer Capacitance of Graphene by Self‐Doped Defects through Ball‐Milling

Synchrotron Soft X‐ray Absorption Spectroscopy Study of Carbon and Silicon Nanostructures for Energy Applications

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