Metal-organic frameworks as template for synthesis of Mn3+/Mn4+ mixed valence manganese cobaltites electrocatalysts for oxygen evolution reaction.
Cobalt-based oxides are among the most promising electrocatalysts for oxygen evolution reactions (OER). In this context, this work reports the synthesis of manganese-doped cobaltites using the Zeolitic-Imidazolate Frameworks 67 (ZIF-67) as template. The incorporation of manganese ions into ZIF-67 structure was evaluated in ethanol and methanol, in order to obtain the best synthetic route. Non-doped (ZIF-67C) and Mn-doped cobaltites (Mn/ZIF-67C(E) and Mn/ZIF-67C(M)) were obtained after thermal treatment at 350 °C. Structural and morphological properties were investigated and presence of Mn3+ and Mn4+ was confirmed by X-ray photoelectron spectroscopy (XPS) data and magnetization curves. The electrocatalytic activity in OER was investigated in alkaline medium for manganese cobaltites, and compared to the ZIF-67C. Overpotentials to generate a current of 10 mA cm-2 were 338 mV and 356 mV for Mn/ZIF-67C(E) and Mn/ZIF-67C(M), respectively. These results are superior to those found for similar materials in the literature. The material obtained in methanol (Mn/ZIF-67C(M)) presents lower overpotential, however, shows superior electrocatalytic performance for current density above 100 mA cm-2, therefore being an efficient electrode for commercial electrolysers.
['Lourenço|Annaíres A|AA|', 'Silva|Vinícius D|VD|', 'da Silva|R B|RB|', 'Silva|U C|UC|', 'Chesman|C|C|', 'Salvador|C|C|', 'Simões|Thiago A|TA|', 'Macedo|Daniel A|DA|', 'da Silva|Fausthon F|FF|']
Oxygen evolution reaction Mn-doped cobaltites ZIF-67 derivatives