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Updated: Feb 22, 2026

Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production
Published on: December 6, 2021
Structural Distortion in MnO₂ Nanosheets and Its Suppression by Cobalt Substitution
Shinya Suzuki1, Masaru Miyayama2
1Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan. sin@fmat.t.u-tokyo.ac.jp.
Abstract:
Co-Mn oxide nanosheets with the chemical composition H0.23Co0.23Mn0.77O₂ (C23M77NS) and MnO₂ nanosheets (M100NS) were prepared by exfoliation of layer-structured oxides via chemical processing in an aqueous medium. The optical properties of C23M77NS and M100NS were compared using UV-Vis spectroscopy, and the valence states of Mn and Co and local structures around them were examined using X-ray absorption spectroscopy. M100NS with an average Mn valence of 3.6 exhibits large structural distortion, whereas C23M77NS with an average Mn valence of 4.0 does not exhibit structural distortion. Spontaneous oxidization of Mn occurs during ion-exchange and/or exfoliation into nanosheets. These results have originated the hypothesis that structural distortion determines the valence state of Mn in compounds with CdI₂-type-structured MnO₂ layers.
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