Nanocomposites and nanomaterial

Synthesis and catalytic properties
of nitrogen-containing carbon nanotubes
Cherniuk O.A., Zhuravskyi S.V., Sementsov Yu.I.,
Kartel M.T., Voitko K.V., Bakalinska O.M.
Chuiko Institute of Surface Chemistry, NAS of Ukraine,
17 General Naumov Str., Kyiv 03164, Ukraine. garbear@ukr.net

Nitrogen-containing carbon nanotubes (N-CNT’s) were obtained by the following methods: 1) calcination CNT’s with urea; 2) direct synthesis of N-CNT’s using ethylendiamine and acetonitryl. The specific surface area of the obtained samples, which is in the range of 200-300 m2/g, was determined by the nitrogen adsorption-desorption method. The structure of the N-CNT’s was characterized by Raman and X-ray photoelectron spectroscopies. The impact of the synthesis methods on the amount and chemical state of nitrogen heteroatoms in the carbon matrix structure was revealed. The catalytic effect of multilayer N-CNT’s obtained both of synthesis methods on the kinetics of decomposition of hydrogen peroxide at different pH in aqueous solutions values was considered.
It was found that the method of direct synthesis of N-CNT’s makes it possible to obtain more catalytically active carbon nanotubes in comparison with method of calcination. Such N-CNT’s contain significantly larger amount of nitrogen (by 7-8 times), predominantly of the pyrol and quaternary type. But regardless of the synthesis method, the maximum catalytic activity in the decomposition of hydrogen peroxide is observed at pH 7 (Fig.1), which is important for the use of such materials for catalysis in biological media.
 
Fig. 1. The velocity constant (a) and the Aphin constant (b)
vs. pH for different CNT’s