Coprecipitation of gold(III) complex ions with manganese(II) hydroxide and their stoichiometric reduction to atomic gold (Au(0)): Analysis by Mössbauer spectroscopy and XPS

Mamiko Yamashita, Hironori Ohashi, Yasuhiro Kobayashi, Yoshihiro Okaue, Tsutomu Kurisaki, Hisanobu Wakita, Takushi Yokoyama

Research output: Contribution to journalArticle

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Abstract

To elucidate the formation process of precursor of gold-supported manganese dioxide (MnO2), the coprecipitation behavior of [AuCl4-n(OH)n]- (n = 0 - 4) (Au(III)) complex ions with manganese(II) hydroxide (Mn(OH)2) and the change in their chemical state were examined. The Au(III) complex ions were rapidly and effectively coprecipitated with Mn(OH)2 at pH 9. According to the Mössbauer spectra for gold (Au) coprecipitated with Mn(OH)2, below an Au content of 60 wt% in the coprecipitates, all of the coprecipitated Au existed in the atomic state (Au(0)), while, above an Au content of 65 wt%, part of the gold existed in the Au(III) state, and the proportion increased with increasing coprecipitated Au content. Based on the results of X-ray photoelectron spectroscopy, Mn(II) in Mn(OH)2 converted to Mn(IV) in conjunction with coprecipitation of Au(III) complex ions. These results indicate that the rapid stoichiometric reduction of Au(III) to Au(0) is caused by electron transfer from Mn(II) in Mn(OH)2 to the Au(III) complex ion through an Mn{single bond}O{single bond}Au bond.

Original languageEnglish
Pages (from-to)25-29
Number of pages5
JournalJournal of Colloid And Interface Science
Volume319
Issue number1
DOIs
Publication statusPublished - Mar 1 2008

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

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