Probing the Structure and Binding Mode of EDTA on the Surface of Mn3O4 Nanoparticles for Water Oxidation by Advanced Electron Paramagnetic Resonance Spectroscopy
Abstract:Identification of the surface structure of nanoparticles is important for understanding the catalytic mechanism and improving the properties of the particles. Here, we provide a detailed description of the coordination modes of ethylenediaminetetraacetate (EDTA) on Mn 3 O 4 nanoparticles at the atomic level, as obtained by advanced electron paramagnetic resonance (EPR) spectroscopy. Binding of EDTA to Mn 3 O 4 leads to dramatic changes in the EPR spectrum, with a 5-fold increase in the axial zero-field splitti… Show more
“…Hausmannite (Mn 3 O 4 ) crystallizes in a tetragonal spinel-like structure ( I 4 1 / amd space group) below 1170 °C because of the Jahn–Teller effect . It has attracted great interest for its potential technological applications in electrocatalysis and water treatment. − It is hypothesized that the Mn(III) instead of Mn(II) or Mn(IV) at the surface are more active catalytically . However, the surface structures are still to be revealed …”
The Mn(III) ions at Mn 3 O 4 surface are hypothesized to contribute to catalytic activity in oxygen reduction reaction. However, the surface structure and stability of Mn 3 O 4 are far less understood. Here, the atomic structures of the widespread ( 101) and (001) surfaces of Mn 3 O 4 are determined by combining aberration-corrected transmission electron microscopy and DFT calculations. The surface stabilization mechanisms and the oxidation states of Mn are revealed and correlated to the catalytic activity of the surfaces. The results show that the (101) surface undergoes a subsurface reconstruction, forming a rock-salt-type surface layer. The Mn(III) ions are in the outermost layer of the (001) surface but in the subsurface of the (101) surface. The surface partition of the Mn(III) ions provides a microscopic understanding to the observed higher catalytic activity of the (001) surface relative to the (101) surface and would contribute to further development of novel catalysts based on Mn 3 O 4 .
“…Hausmannite (Mn 3 O 4 ) crystallizes in a tetragonal spinel-like structure ( I 4 1 / amd space group) below 1170 °C because of the Jahn–Teller effect . It has attracted great interest for its potential technological applications in electrocatalysis and water treatment. − It is hypothesized that the Mn(III) instead of Mn(II) or Mn(IV) at the surface are more active catalytically . However, the surface structures are still to be revealed …”
The Mn(III) ions at Mn 3 O 4 surface are hypothesized to contribute to catalytic activity in oxygen reduction reaction. However, the surface structure and stability of Mn 3 O 4 are far less understood. Here, the atomic structures of the widespread ( 101) and (001) surfaces of Mn 3 O 4 are determined by combining aberration-corrected transmission electron microscopy and DFT calculations. The surface stabilization mechanisms and the oxidation states of Mn are revealed and correlated to the catalytic activity of the surfaces. The results show that the (101) surface undergoes a subsurface reconstruction, forming a rock-salt-type surface layer. The Mn(III) ions are in the outermost layer of the (001) surface but in the subsurface of the (101) surface. The surface partition of the Mn(III) ions provides a microscopic understanding to the observed higher catalytic activity of the (001) surface relative to the (101) surface and would contribute to further development of novel catalysts based on Mn 3 O 4 .
“…S7 †). 51 IR analysis and PXRD showed that there was no significant change after illumination (Fig. S8 †), which ruled out the possibility of photoisomerization and photodecomposition.…”
Smart chromic materials with physicochemical stimuli were widely applied in optical switches, smart windows, and chemical sensors. Currently, most materials only respond to a single stimulus, but those with multiple...
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