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HESIS AND PROPERTIES OF INORGANIC COMPOUNDS

Synthesis of CaCu3Ti4O12, Study of Physicochemical and Photocatalytic Properties K. V. Ivanova, *, O. V. Alekseevaa, and A. V. Agafonova aKrestov

Institute of Solution Chemistry, Russian Academy of Sciences, Ivanovo, 153045 Russia *e-mail: [email protected] Received May 7, 2020; revised May 25, 2020; accepted May 27, 2020

Abstract―Precursor CaCu3Ti4O12 has been obtained using solution method in acetic acid medium, it was annealed at 100, 200, 400, 600 800, and 1100°C. Sintered powders have been studied by physicochemical methods of analysis. According to X-ray powder diffraction, completely formed crystal structure CaCu3Ti4O12 exists at 1100°C, the particle size of the prepared powder is 1–10 μm. Thermal analysis with allowance for mass spectrometric analysis system of vapor phase has revealed process mechanisms. Effect of dried at 100°C powder of precursor and CaCu3Ti4O12 on the photocatalytic activity of Rhodamine B decoloration has been shown. Pseudo-first and pseudo-second order kinetics for Rhodamine B adsorption on samples annealed at 100 and 1100°C has been revealed. Keywords: thermal treatment, synthesis, kinetics, photocatalytic activity DOI: 10.1134/S0036023620100095

INTRODUCTION In recent time, a large attention is attracted to the studies of photocatalytic activity of materials with perovskite structure to design photocatalysts [1, 2] useful in decontamination systems of aqueous and air media from organic molecules (dyes, pharmaceuticals) and bacteria [3–5]. The development of photocatalysts active on exposure to visible light is of special interest. However, widely known titanium dioxide used as photoactive material has drawbacks due to its low photosensitivity in visible spectral region because of large band gap width. One of the methods to extend TiO2 absorption region to visible spectrum is the doping of titanium dioxide with transition metals or other compounds. A number of works were devoted to study metal oxides [6], hybrid [7], hetero structurized [8], and other systems. Literature provides the data on the investigation of materials with perovskite structure such as BaTiO3 [9], SrTiO3 [10], CaTiO3 [11], LaFeO3 [12], etc., showing good photocatalytic activity. However, they have wide band gaps (>3 eV) and can be activated only in ultraviolet light [13]. The authors [14] found that CaCu3Ti4O12 (CCTO) has two band gaps: 1.93 and 2.21 eV. Therefore the study of photocatalytic properties of CCTO, which is double cubic perovskite [15] prepared by different methods, seems to be topical because it combines the photocatalytic properties of TiO2 [16] showing high activity in ultraviolet and CuO that absorbs visible light. The combination of properties of these oxides in CCTO should favor to photocatalytic activity

in visible light resulting from charge transfer in visible light from the main to the excited state. Titanium dioxide is known to show antimicrobial and antimycotic properties preferably on exposure to light [17]. The doping of TiO2 with metal ions or