MOF Derived Manganese Oxides Nanospheres Embedded in N-Doped Carbon for Oxygen Reduction Reaction.

Manganese oxides (MnO_x) have been regarded as promising catalyst candidates for oxygen reduction reaction (ORR) due to their natural abundance and extremely low toxicity. However, the intrinsic low conductivity of MnO_x limits their application. In this work, Mn oxide embedded in N doped porous carbon (MnO_x@C-N) electrocatalysts were prepared through a facile zeolitic imidazolate framework (ZIF-8) template method for ORR. The structure, morphology, and composition of the prepared materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Electrocatalytic performances of the prepared materials were investigated by linear sweep voltammetry. Benefiting from the well-defined morphology, high surface area, and porous structure, the MnO_x@C-N electrocatalyst showed the highest ORR activity among all investigated materials with the limiting current density of 5.38 mA/cm² at a rotation speed of 1600 rpm, the positive half-wave potential of 0.645 V vs. RHE, and the electron transfer number of 3.90. This work showcases an effective strategy to enhance ORR activity of MnO_x. [ABSTRACT FROM AUTHOR]