移行金属ナノ粒子の表面反応におけるエネルギーバリアとしてのリガンドシェル

Jeremy G Smith¹, Prashant K Jain^1,2,3

¹Department of Chemistry, University of Illinois , Urbana-Champaign, Illinois 61801 United States.

Journal of the American Chemical Society

|May 7, 2016

まとめ

金属ナノ粒子のリガンドコーティングは,イオン輸送のためのエネルギーバリアを作成することによって,触媒反応を大幅に阻害します. この効果は光で調節可能でナノ粒子の大きさや形よりも影響力があります

科学分野:

表面化学
ナノ粒子触媒
材料科学

背景:

移行金属ナノ粒子は触媒作用に不可欠ですが,その表面リガンド層は十分に理解されていません.
ナノ粒子表面のリガンドは反応性に影響を与えますが,その程度とメカニズムは不明です.

研究の目的:

表面に吸収されたチオールリガンドが,銀 (Ag) ナノ粒子の反応性に与える影響を調査する.
リガンドの鎖長と反応運動の関係を定量化する.

主な方法:

Agナノ粒子とAu3+) イオン間のガルバン交換反応を研究した.
個々のナノ粒子の運動を測定するために,在位光学散射スペクトロスコーピーを利用した.
系統的に変化したチオルの連鎖長.

主要な成果:

表面のチオール層は,ガルバン交換反応の運動を大きく阻害する.
シアール鎖の長さが増加すると,ナノ粒子の反応性が体系的に低下した.
光照射はチオール金属結合を弱めることで,リガンド層のバリア効果を低下させた.

結論:

表面のリガンド層はイオン輸送に重要なエネルギーバリアとして作用し,ナノ粒子の反応性に影響します.
反応性に対するリガンド効果は,ナノ粒子サイズ,形状,または結晶性よりも優勢です.
この発見は,ナノ粒子のコロイド触媒,光触媒,表面被動化を理解し,設計する上で極めて重要です.

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