PURIFICATION FEATURES OF CARBON NANOTUBES FROM IMPURITIES AFTER THEIR SYNTHESIS
Abstract
The influence of multi-stage liquid-phase chemical treatment of carbon nanotubes obtained CVD method on the quantitative and qualitative composition of their array was studied, as well as the state of their structures for the selection of optimal conditions for cleaning this material from impurities. The synthesis of carbon nanotubes was carried out using a catalyst based on iron oxides and molybdenum deposited on finely dispersed alumina and methane as a carbon reagent. The act of chemical reagents on the degree of purification and the state of the structure of the walls of carbon nanotubes was studied at all stages of the multistage chemical treatment of the obtained material. The complete purification cycle of synthesized carbon nanotubes from associated impurities included treatments with concentrated aqueous solutions of such chemicals as hydrochloric acid (concentration 11.5 M), hydrogen peroxide (concentration 8.8 M), nitric acid (concentration 15 M). Changes in the qualitative and quantitative compositions, structural characteristics of materials, obtained in stages in the multi-stage method used to clean carbon nanotubes from impurities, have been studied by means of physicochemical methods such as X-ray energy-dispersive spectroscopy, Raman spectroscopy, and transmission electron microscopy. It has been established that for efficient cleaning of carbon nanotubes, which are small-walled nanotubes, it is necessary to carry out sequential treatment of raw material with solutions of hydrochloric acid and hydrogen peroxide. A positive effect on the cleaning quality of the small-walled carbon nanotubes synthesized by the CVD method is provided by finishing with a solution of nitric acid. In this case, it is necessary to optimize the duration of the preliminary stage using a hydrogen peroxide solution to prevent the destructive action of nitric acid on the structure of carbon nanotubes.
Forcitation:
Tabulina L.V., Rusalskaya T.G., Shulitsky B.G., Shaman Y.P., Komissarov I.V., Carosa A.G. Purification features of carbon nanotubes from impurities after their synthesis. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 6. P. 89-94.
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