Au/TiO2酸化触媒の周縁部位における反応酸素による抑制
Isabel Xiaoye Green1, Wenjie Tang, Monica McEntee
1Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States.
Journal of the American Chemical Society
|June 29, 2012
まとめ
二酸化チタンで支えられた金のナノ粒子は,酸化反応の触媒活性を示しています. 黄金のナノ粒子をプレオキシド化することで,二重触媒部位にある陽性電荷の金原子による一酸化炭素の酸化を抑制する.
科学分野:
- 材料科学 材料科学とは
- カタリシス カタリシス カタリシス
- 表面化学について
背景:
- 大量ゴールドは酸化反応に触媒的に無効である.
- 二酸化チタン (TiO2) に支えられた金のナノ粒子は,予期せぬ触媒的活性を示します.
- 触媒的活動は,金ナノ粒子の周縁に限られ,TiO2サポートとインタフェースする.
研究 の 目的:
- TiO2-サポートされた金のナノ粒子における触媒活動の起源を調査する.
- これらのナノ材料におけるCO酸化のメカニズムを理解するために.
- 触媒における反応物種による自己抑制の現象を調査する.
主な方法:
- 低温 (120 K) でのCO酸化反応速度に関する実験的研究.
- 金ナノ粒子のプレオキシデーションにより,表面の変化を誘発する.
- 電子構造と反応経路をモデル化するための理論的計算.
- 金とTiO2.2を含む二重触媒性サイトの分析.
主要な成果:
- TiO2 サポートされた金のナノ粒子は,酸化反応のための重要な触媒活性を示しています.
- CO酸化率は,金ナノ粒子を120Kで前酸化した時に22の因数で減少した.
- プレオキシデーションは,周囲の金原子に酸素誘発の正電荷をもたらします.
- 理論的な計算は,陽性電荷による二重触媒部位でのCO酸化の活性化エネルギーの増加を確認しています.
結論:
- TiO2-サポートされた金のナノ粒子の触媒的活動は,金とTiO2.2の間のインターフェイス (周辺) に局所されています.
- 金とTi (((4+) を含む二重触媒サイトは,酸素分子を効率的に活性化します.
- 金ナノ粒子のプレ酸化は,陽性電荷の金原子を作り,活性化エネルギーを増加させることで,CO酸化の自己抑制につながります.
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