| Abstract | In this paper, Magneli phase Ti₄O₇ was successfully synthesized using a TiO₂ reduction method, and characterized using X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The electrode coated with this Ti₄O₇ material showed activities for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). For the ORR, several parameters, including overall electron transfer number, kinetic constants, electron transfer coefficient, and percentage H₂O₂ production, were obtained using the rotating ring-disk electrode (RRDE) technique and the Koutecky–Levich theory. The overall electron transfer number was found to be between 2.3 and 2.9 in 1, 4, and 6M KOH electrolytes, suggesting that the ORR process on the Ti₄O₇ electrode was a mixed process of 2- and 4-electron transfer pathways. Electrochemical durability tests, carried out in highly concentratedKOH electrolyte, confirmed that this Ti₄O₇ is a stable electrode material, suggesting that it should be a feasible candidate for the aircathodes of zinc-air batteries. To understand the stability of this material, Raman and XPS spectra were also collected for the Ti₄O₇ samples before and after the stability tests. The results and analysis revealed that a thin layer of TiO₂ formed on the Ti₄O₇ surface, which may have prevented further oxidation into the bulk of the Ti₄O₇ electrode. |
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