Annealing of C in hydrogen at temperatures above the stability limit of C-H bonds in CH (500-550 °C) is found to result in direct collapse of the cage structure, evaporation of light hydrocarbons, and formation of solid mixture composed of larger hydrocarbons and few-layered graphene sheets. Only a minor part of this mixture is soluble; this was analyzed using matrix-assisted laser desorption/ionization MS, Fourier transform infrared (FTIR), and nuclear magnetic resonance spectroscopy and found to be a rather complex mixture of hydrocarbon molecules composed of at least tens of different compounds. The sequence of most abundant peaks observed in MS, which corresponds to CH mass difference, suggests a stepwise breakup of the fullerene cage into progressively smaller molecular fragments edge-terminated by hydrogen. A simple model of hydrogen-driven C unzipping is proposed to explain the observed sequence of fragmentation products. The insoluble part of the product mixture consists of large planar polycyclic aromatic hydrocarbons, as evidenced by FTIR and Raman spectroscopy, and some larger sheets composed of few-layered graphene, as observed by transmission electron microscopy. Hydrogen annealing of C thin films showed a thickness-dependent results with reaction products significantly different for the thinnest films compared to bulk powders. Hydrogen annealing of C films with the thickness below 10 nm was found to result in formation of nanosized islands with Raman spectra very similar to the spectra of coronene oligomers and conductivity typical for graphene.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3970553 | PMC |
| http://dx.doi.org/10.1021/jp500377s | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Inert Liquid Exfoliation and Langmuir-Type Thin Film Deposition of Semimetallic Metal Diborides.
ACS Nano
October 2024
School of Physics, CRANN & AMBER Research Centres, Trinity College Dublin, Dublin 2, Ireland.
Article Synopsis
- Graphite can be turned into nanosheets with semimetallic properties, but its work function limits compatible materials for printed electronic devices, prompting the search for other 2D materials.
- Metal diborides, layered crystals with semimetallic qualities, are explored as potential substitutes, and a new inert exfoliation process for making quasi-2D nanoplatelets (MgB, CrB, ZrB) is introduced with minimal oxidation.
- The study validates these nanoplatelets for electrical applications and presents a cost-effective method to protect them, showcasing their effectiveness in creating strain sensors, positioning them as viable alternatives to graphene in electronics.
An environmentally sustainable ultrasonic-assisted exfoliation approach to graphene and its nanocompositing with polyaniline for supercapacitor applications.
Ultrasonics
January 2025
Department of Chemistry, University of Calicut, Calicut University (PO), Malappuram DT, Kerala - 673635, India. Electronic address:
Article Synopsis
- A new eco-friendly method for producing graphene using ultrasonic-assisted liquid phase exfoliation (LPE) in a green solvent is presented, achieving a high concentration of 3.2 mg/ml in just 3 hours of ultrasonication.
- The method combines acetophenone and isopropyl alcohol to enhance the exfoliation of graphite, resulting in high-yield (16%) turbostratic graphene with fewer defects, confirmed through various characterization techniques.
- The study further explores the use of the conductive polymer polyaniline (PANI) combined with graphene for supercapacitor applications, showing that the PANI/graphene nanocomposite achieves the highest specific capacitance of 126.16 mF/cm at a current density
Modality-Tunable Exfoliated N-Doped Graphene as Effective Electrolyte Additive for High-Performance Lithium-Sulfur Batteries.
ACS Appl Mater Interfaces
October 2024
Robert Fredrick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States.
While chemically doped graphene has shown great promise, the lack of cost-effective manufacturing has hindered its use. This study utilizes a facile fabrication approach for modality-tunable N-doped graphene via thermal annealing of aqueous-phase-exfoliated few-layered graphene from a Taylor-Couette reactor. This method demonstrates a high level of N-doping (27 atom % N) and offers modality tunability of the C-N bond without foregoing scalability and green chemistry principles.
View Article and Find Full Text PDFIncommensurate charge super-modulation and hidden dipole order in layered kitaev material α-RuCl.
Nat Commun
September 2024
International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China.
The magnetism of Kitaev materials has been widely studied, but their charge properties and the coupling to other degrees of freedom are less known. Here we investigate the charge states of α-RuCl, a promising Kitaev quantum spin liquid candidate, in proximity to graphite. We discover that few-layered α-RuCl experiences a clear modulation of charge states, where a Mott-insulator to weak charge-transfer-insulator transition in the 2D limit occurs by means of heterointerfacial polarization.
View Article and Find Full Text PDFEx Situ Covalent Functionalization of Germanene via 1,3-Dipolar Cycloaddition: A Promising Approach for the Bandgap Engineering of Group-14 Xenes.
Small
November 2024
Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen, 9747 AG, the Netherlands.
Article Synopsis
- Group-14 Xenes like silicene, germanene, and stanene are being explored for their unique electronic properties that can be modified through covalent functionalization.
- A new method for creating thin layers of covalently functionalized germanene through a chemical reaction has been introduced, producing sheets only about 6 nm thick, much thinner than previous methods.
- The functionalization process increases the optical bandgap of germanene by 500 meV, indicating potential for advanced applications in electronics and catalysis.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!