Effect of substrate temperature on the structure of amorphous oxygenated hydrocarbon films grown with a pulsed supersonic methane plasma flow

A detailed analysis of TUBALL single‐walled carbon nanotubes (SWCNTs) after two‐step purification involving acid purification treatment with concentrated HCl, HNO3, H2SO4 and solution of HNO3:H2SO4 followed by magnetic processing is presented. The purity degree from iron higher than 99% is achieved, and the yield obtained by the above process is about 75 wt.%. Such high purity of the resultant sample is achieved by removing of the external iron nanoparticles by acid treatment and following extraction of nanotubes containing encapsulated nanoparticles under applied magnetic field. A comprehensive characterization of SWCNTs by Raman, optical absorption, and X‐ray photoelectron spectroscopies reveals purification‐induced changes in the integrity, composition, and electronic properties of SWCNT.

Section: Resultsmentioning

confidence: 99%

Purification of Single‐Walled Carbon Nanotubes Using Acid Treatment and Magnetic Separation

Gurova

Arhipov

Koroteev

et al. 2019

“…The amount of hydroxyl and carbonyl groups is reduced as compared to the initial material. A large contribution in RGO‐COOH spectrum is made by the peak E, corresponding to carboxyl groups, which indicates the selective addition of carboxyl groups to the surface of the material during the synthesis . In addition, it was calculated from the XPS data that in the initial RGO contained about 3% of COOH group of all carbon atoms.…”

Section: Resultsmentioning

confidence: 99%

Redox Processes in Reduced Graphite Oxide Decorated by Carboxyl Functional Groups

Kobets

Iurchenkova

Asanov

et al. 2019

The reduction of graphite oxide makes it possible to obtain a graphene material with a developed surface, high conductivity and remarkable electrochemical behavior. The study of the electrochemical activity of oxygen‐containing functional groups on the graphene surface is important for the creation of electrochemical energy sources and sensors. In this work, the reduced graphite oxide is selectively decorated by carboxyl functional groups. The initial and carboxylated reduced graphite oxide are studied by SEM microscopy, FTIR, Raman, and X‐ray photoelectron spectroscopy. It is shown that a large number of carboxyl groups added to reduced graphite oxide surface change the sample morphology. Studying of reduced graphite oxide and carboxylated reduced graphite oxide by cyclic voltammetry shows reversible redox processes, which is associated with oxidation and reduction of the hydroxyl, carbonyl, and carboxyl groups. In addition, the dependence of peak potentials on the pH value is studied.

“…The XPS C 1s spectrum of GO buckypaper (Figure ) detected three main forms of carbon atoms. A low‐energy spectral component at 284.5 eV is commonly assigned to the sp 2 ‐hybridized carbon atoms, constituting non‐functionalized graphene areas, two high‐energy components at 286.7 and 288.5 eV correspond to the CO and CO species, respectively . In the GO buckypaper, the main part of oxygen in the sample is present in the СО from (75%), and only fourth part of oxygen is in carbonyl or carboxyl groups.…”

Section: Resultsmentioning

confidence: 99%

Electromagnetic Properties of Reduced Graphene Oxide Buckypapers Obtained by Different Reduction Procedures

Kanygin

Stolyarova

Dorojkin

et al. 2017

Transmission properties of graphene oxide (GO) buckypapers reduced by different methods were investigated in the sub-THz range from 250 to 650 GHz. The reduction of GO films was performed by annealing and by interaction with hydrazine vapor. It was found that the chemical treatment is more effective for oxygen group removal than the thermal treatment. Based on the data of X-ray photoelectron and Raman spectroscopy measurements, the changes of the absorption properties of the investigated samples were attributed to the formation of additional defects and vacancies during reduction processes. Additionally, the influence of the duration of chemical reduction on the absorption properties of buckypaper in the sub-THz range was investigated.