A composite formation route to well-crystalline manganese oxide nanocrystals: High catalytic activity of manganate-alumina nanocomposites

Tae Woo Kim, Hana Yoo, In Young Kim, Hyung Wook Ha, Ah Reum Han, Jong San Chang, Ji Sun Lee, Seong Ju Hwang

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

Manganese oxide nanocrystals are combined with aluminum oxide nanocrystals to improve their crystallinity via calcination without a significant increase of crystal size. A nanocomposite, consisting of two metal oxides, can be synthesized by the reaction between permanganate anions and aluminum oxyhydroxide keggin cations. The as-prepared manganese oxide-aluminum oxide nanocomposite is X-ray amorphous whereas heat-treatment gives rise to the crystallization of an α-MnO2 phase at 600 °C and Mn 3O4/Mn2O3 and γ-Al 2O3 phases at 800 °C. Electron microscopy and N 2 adsorption-desorption-isotherm analysis clearly demonstrate that the as-prepared nanocomposite is composed of a porous assembly of monodisperse primary particles with a size of ∼20 nm and a surface area of >410 m 2 g-1. Of particular interest is that the small particle size of the as-prepared nanocomposite is well-maintained up to 600 °C, a result of the prevention of the growth of manganate grains through nanoscale mixing with alumina grains. The calcined nanocomposite shows very-high catalytic activity for the oxidation of cyclohexene with an extremely high conversion efficiency of >95% within 15 min. The present results show that the improvement of the crystallinity without significant crystal growth is very crucial for optimizing the catalytic activity of manganese oxide nanocrystals.

Original languageEnglish
Pages (from-to)2301-2310
Number of pages10
JournalAdvanced Functional Materials
Volume21
Issue number12
DOIs
Publication statusPublished - 2011 Jun 21

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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