Polymer stabilizer effect on the nickel-copper ferrite ability to reduction
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Russian Chemical Bulletin, International Edition, Vol. 69, No. 8, pp. 1428—1435, August, 2020
Full Articles Polymer stabilizer effect on the nickel-copper ferrite ability to reduction* N. M. Ivanova, E. A. Soboleva, and Ya. A. Visurkhanova Institute of Organic Synthesis and Coal Chemistry of the Republic of Kazakhstan, 1 ul. Alikhanova, 100008 Karaganda, Kazakhstan. E-mail: [email protected] The effect of polymers (polyvinyl alcohol, polyvinylpyrrolidone) involved in the synthesis of nickel-copper ferrite Ni0.5Cu0.5Fe2O4 on its phase composition changing under heat treatment (500—900 C) and electrochemical reduction was investigated. Electrocatalytic activity of various levels of Fe—Cu—Ni-composites formed by the reduction of the mixed ferrite samples was established. An influence of heat treatment temperature on their electrocatalytic activity in the electrohydrogenation of acetophenone was studied. Key words: nickel-copper ferrite, co-precipitation method, polyvinyl alcohol, polyvinylpyrrolidone, heat treatment, electrochemical reduction, electrocatalytic hydrogenation, acetophenone.
Currently, considerable attention is paid to nanoscale transition metal ferrites MFe2O4 (M = Ni2+, Mn2+, Co2+, Cu2+, Zn2+) due to their diverse properties, including catalytic1—5 and electrochemical,6,7 and promising fields of their application (magneto-optics, spintronics, biomedicine, etc.). Mixed ferrites of metals belong also to the same group of materials with a spinel structure. The M cations in them can be represented by two or more metals in specified ratios that determine properties, structural and morphological features of ferrites. Thus, nickel and copper ferrite of the general formula NiCuFe2O4 having an inverse spinel structure similar to NiFe2O48 belongs to softer magnetic materials than undoped nickel(II) ferrite.9 * Based on the materials of the XXI Mendeleev Congress on General and Applied Chemistry (September 9—13, 2019, St. Petersburg, Russia).
A variety of methods has been developed at present for fabrication of nanoscale particles of metal ferrites. These include the sol—gel method, hydrothermal, ceramic, and microemulsion methods, self-combustion, co-precipitation, mechanical and microwave synthesis, and others. It is mentioned in many publications that the properties of obtained metal ferrites depend on the method of preparation. The formation of a sol and then a dry gel in sol—gel methods and methods involving self-combustion occurs in the presence of organic matter, which burns out during subsequent heat treatment. As a result nanodispersed ferrite powder remains. Both monomeric (ethylene glycol, citric and maleic acids, urea, etc.10—13) and polymeric reagents (polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyacrylic acid, etc.14—16) are used as an organic binder. Mixed nickel-copper ferrites with different metal ratios were obtained using the sol—gel method. The effect
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1428—1435, August, 2020. 1066-5285/20/6908-1428 © 20
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