title: Manganese oxide phases and morphologies: A study on calcination temperature and atmospheric dependence.
abstract: Manganese oxides are one of the most important groups of materials in energy storage science. In order to fully leverage their application potential, precise control of their properties such as particle size, surface area and Mn (x) (+) oxidation state is required. Here, Mn3O4 and Mn5O8 nanoparticles as well as mesoporous α-Mn2O3 particles were synthesized by calcination of Mn(II) glycolate nanoparticles obtained through an economical route based on a polyol synthesis. The preparation of the different manganese oxides via one route facilitates assigning actual structure-property relationships. The oxidation process related to the different MnO x species was observed by in situ X-ray diffraction (XRD) measurements showing time- and temperature-dependent phase transformations occurring during oxidation of the Mn(II) glycolate precursor to α-Mn2O3 via Mn3O4 and Mn5O8 in O2 atmosphere. Detailed structural and morphological investigations using transmission electron microscopy (TEM) and powder XRD revealed the dependence of the lattice constants and particle sizes of the MnO x species on the calcination temperature and the presence of an oxidizing or neutral atmosphere. Furthermore, to demonstrate the application potential of the synthesized MnO x species, we studied their catalytic activity for the oxygen reduction reaction in aprotic media. Linear sweep voltammetry revealed the best performance for the mesoporous α-Mn2O3 species.
authors: Fraunhofer Institute for Manufacturing Technology and Advanced Materials, Wiener Str. 12, 28359 Bremen, Germany ; Department of Physics, Energy and Semiconductor Research Laboratory, Carl von Ossietzky University of Oldenburg, 26129 Oldenburg, Germany.
authors: Matthias
authors: M
authors: Augustin
authors: Fraunhofer Institute for Manufacturing Technology and Advanced Materials, Wiener Str. 12, 28359 Bremen, Germany.
authors: Daniela
authors: D
authors: Fenske
authors: Fraunhofer Institute for Manufacturing Technology and Advanced Materials, Wiener Str. 12, 28359 Bremen, Germany.
authors: Ingo
authors: I
authors: Bardenhagen
authors: Fraunhofer Institute for Manufacturing Technology and Advanced Materials, Wiener Str. 12, 28359 Bremen, Germany.
authors: Anne
authors: A
authors: Westphal
authors: Department of Physics, Energy and Semiconductor Research Laboratory, Carl von Ossietzky University of Oldenburg, 26129 Oldenburg, Germany.
authors: Martin
authors: M
authors: Knipper
authors: Department of Physics, Energy and Semiconductor Research Laboratory, Carl von Ossietzky University of Oldenburg, 26129 Oldenburg, Germany.
authors: Thorsten
authors: T
authors: Plaggenborg
authors: Department of Physics, Energy and Semiconductor Research Laboratory, Carl von Ossietzky University of Oldenburg, 26129 Oldenburg, Germany.
authors: Joanna
authors: J
authors: Kolny-Olesiak
authors: Department of Physics, Energy and Semiconductor Research Laboratory, Carl von Ossietzky University of Oldenburg, 26129 Oldenburg, Germany.
authors: Jürgen
authors: J
authors: Parisi
keywords: electrocatalytic activity; in situ X-ray diffraction; manganese glycolate; manganese oxide nanoparticles; mesoporous α-Mn2O3