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    Öğe
    Manganese Oxoborate-Based Nanostructures as Novel Oxygen Evolution Catalysts in Neutral Media
    (Wiley-V C H Verlag Gmbh, 2021) Elmacı, Gökhan; İçten, Okan; Özer, Demet; Özgenç, Gökhan; Ertekin, Zeliha; Köse, Dursun Ali; Zümreoğlu Karan, Birgül
    The development of electrocatalysts for the OER (oxygen evolution reaction) process is an ongoing challenge in producing sustainable energy systems. Herein, we report QS (quasi-spherical), IR (irregular), and NR (nanorod) Mn2OBO3 (manganese oxoborate), modified with a carbon support, as candidate electrocatalysts for OER in a neutral medium. QS-, IR- and NR-Mn2OBO3 catalysts displayed low onset potentials of 201 mV, 205 mV, and 208 mV and Tafel slope results of 94 mV dec(-1), 97 mV dec(-1), and 106 mV dec(-1), respectively. As a result of the long-term stability tests, it was determined that the NR-Mn2OBO3 sample was extremely stable compared to the QS- and IR-catalysts. This work introduces a new Mn2OBO3/C composite catalyst that displays efficient OER performance at a neutral medium and provides a different perspective for catalyst development strategies.
  • [ X ]
    Öğe
    Synthetic routes to manganese oxoborate and correlations between experimental parameters and properties
    (Elsevier Sci Ltd, 2021) İçten, Orkun; Özgenç, Gökhan; Özer, Demet; Köse, Dursun Ali; Elmacı, Gökhan; Ertekin, Zeliha; Zümreoğlu Karan, Birgül
    This study examines manganese oxoborate synthesis in three different routes and the role of process parameters on structure and morphology of the products. Borax or boric acid and simple manganese salts were used as raw materials. In this regard, the samples prepared by hydrothermal, solid-state, and solution combustion methods were characterized by powder X-ray diffraction (XRD), vibrational spectroscopy (FT-IR and Raman), thermal analysis (DSC and TGA), scanning and transmission electron microscopy (SEM and TEM), chemical analysis and BET surface area measurements. It was found that all three strategies yielded warwickite-type Mn2OBO3 nanoparticles, but with significant changes in morphology, size, and surface characteristics. The hydrothermal approach has proven to be a general approach for synthesizing manganese oxoborate nanorods at pH 7.5. Solution combustion technique appeared the most practical and promising not only as a time-saving route but also in the production of ca. 100 nm, quasi-spherical, mesoporous manganese oxoborate nanoparticles.