Nanocomposites and nanomaterials

Synthesis, structure, and electrochemical properties of chromium-doped supramolecular carbon material
Ptashnyk V.V.1, Bordun I.M.2,3, Całus D.2, Chabecki P.2, Maksymych V.M.3, Malovanyy M.S.3, Borysiuk A.K.3
1 Lviv National Agrarian University, 1, Vol. Velykogo str., Dubliany-Lviv, 80381, Ukraine.
E-mail: ptashnykproject@gmail.com
2 Czestochowa University of Technology, 69, Dabrowskiego str., Czestochowa, 42-201, Poland.
3 Lviv Polytechnik National University, 12, Bandera str., Lviv, 79013, Ukraine.

One of the ways to increase the efficiency of electric charge accumulation by electrochemical systems based on the principle of a double electric layer is the use of activated carbon materials synthesized from precursors with supramolecular structure. Such substances can accommodate in their internal microstructure the certain doping substances, which at the stage of carbonization regulate the electronic structure of the obtained nanoporous carbon material. Based on these considerations, in this paper, the synthesis of carbon materials has been carried out and their properties have been investigated whose the initial precursor was chosen to be β-cyclodextrin and as the doping element, the chromium served.
The synthesis of carbon material was carried out in three stages. In the first and second stages, β-cyclodextrin was carbonized. The synthesis took place in a reactor with a flowing inert atmosphere. In the first stage, β-cyclodextrin was kept at 500 °C for 5 hours. In the second stage, it was kept at 800 °C for 4 hours. Upon completion, the carbonate was sunk in a solution of oxygen with CrCl3; the mass ratio of carbonate: oxygen was 1:4, and the salt of chromium (III) chloride was introduced at the amount of 4 wt.%-10 wt.% of chromium per 1 g of carbonate. The processed carbonate was dried and in the third stage of carbonization, it was kept at 800 °C for 2 hours in an inert atmosphere.
The structure and morphological features of the synthesized carbon material were studied by scanning electron microscopy, X-ray diffractometry, and low-angle X-ray scattering; the electrochemical properties were investigated using impedance spectroscopy and chronopotentiometry methods. It has been established that the concentration of chromium of 4 wt.% is optimal for the symmetric charge accumulation systems, which provides a specific capacity of such systems of 195 F/g.