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X-RAY ABSORPTION SPECTROSCOPY STUDY OF Mn₂O₃ AND Mn₃O₄ NANOPARTICLES SUPPORTED ON MESOPOROUS SILICA SBA-15

Y.-F. HAN

Institute of Chemical and Engineering Sciences, 1, Pesek Road, Jurong Island, Singapore 627833, Singapore

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K. RAMESH

Institute of Chemical and Engineering Sciences, 1, Pesek Road, Jurong Island, Singapore 627833, Singapore

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L. W. CHEN

Institute of Chemical and Engineering Sciences, 1, Pesek Road, Jurong Island, Singapore 627833, Singapore

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F. X. CHEN

Institute of Chemical and Engineering Sciences, 1, Pesek Road, Jurong Island, Singapore 627833, Singapore

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, and

A. BORGNA

Institute of Chemical and Engineering Sciences, 1, Pesek Road, Jurong Island, Singapore 627833, Singapore

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https://doi.org/10.1142/S1793617908000112Cited by:7 (Source: Crossref)

Abstract

Mn K-edge absorption measurements were carried out on α-Mn₂O₃ and Mn₃O₄ nanocrystals supported on a mesoporous silica, SBA-15. The X-ray absorption near edge structure (XANES) spectra demonstrate the existence of the oxidation states of Mn (2+ and 3+) in Mn₃O₄ and Mn (3+) in Mn₂O₃, those ions were present in different octahedral environments. Meanwhile, XANES data demonstrate that some Mn atoms that are bonding to the inner wall of the channels as isolated species, may exist as Mn⁴⁺ in Mn₂O₃/SBA-15. In addition, the structure, texture, and electronic properties of nanocomposites were also studied using various characterization techniques including X-ray diffraction (XRD) and laser Raman spectroscopy (LRS). The formation of the hausmannite Mn₃O₄ and bixbyite Mn₂O₃ structures has been confirmed clearly by XRD. The prepared nanocomposites of MnO_x showed significant catalytic activity towards CO oxidation below 523 K.

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