Browsing by Author "Dimitrov O."

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    CORRELATION BETWEEN AGING TIME PERIOD OF METAL PRECURSOR SOL - PHASE COMPOSITION AND TEXTURAL PROPERTIES OF ZIRCONIA NANOPOWDERS
    (2024-01-01) Mitkova E.; Stambolova I.; Stoyanova D.; Toteva V.; Dimitrov O.
    This article investigates the effect of the time of aging of ZrO2 powders, obtained from zirconium butoxide sols, stabilized using complexating agents on the volume phase fractions tetragonal phase (T) and baddeleyite crystalographic phase (B), pore size distribution and pore volume. It was proved that the aging time period influences ratio between these two polymorphs of zirconia. The sample Zr3d possesses the largest content of baddeleyite phase having the greatest crystallites in comparison to another two powders. The increasing of aging period leads to a gradual increase in (101) peak intensity of T phase, while all the samples are microporous regardless of the aging time. The longest time aged sample possesses higher pore volume and higher average pore diameter than the other two powders. The physico-chemical features of the prepared ZrO2 nanosized powders could be beneficial as catalysts/photocatalysts in different catalytic reactions, corrosion inhibition particles, etc.
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    Natural Zeolite-Cellulose Phosphate Nanocomposites: Preparation and Advance Electrochemical Study
    (2023-07-01) Tsacheva I.; Dimitrova M.; Gigova A.; Dimitrov O.; Uzun D.
    The scope of this research study is to investigated the green method for preparing and applying cost-effective and environmentally friendly electrocatalytic materials from natural zeolite (clinoptilolite) and cellulose phosphate using microwave irradiation. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX) and Brunauer-Emmett-Teller (BET), were used for the physicochemical characterization of nanocomposites. The newly obtained nanocomposites were studied electrochemically using cyclic voltammetry, linear sweep, galvanostatic measurements, and Tafel slopes. The results show that the obtained nanocomposites can find applications as promising electrocatalytic materials for seawater electrolysis for hydrogen production at oxygen evolution reactions (OER) and for electrochemical purification of organic pollutants.