イオンは水面構造を調節し,シリカ表面での水害性相互作用を調節する

Aashish Tuladhar^1,2, Shalaka Dewan¹, Simone Pezzotti³

¹Department of Chemistry, Temple University, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States.

Journal of the American Chemical Society

|April 3, 2020

まとめ

イオンはインターフェースの電気二重層 (EDL) を変化させる. 水と水の相互作用を促進し,2Dの水素結合ネットワークを作り,O-Hストレッチモードの寿命を短縮し,表面の水嫌性を増加させます.

科学分野:

物理化学
表面科学
スペクトロスコーピー

背景:

電気二重層 (EDL) はインターフェイス特性を支配するが,スターン層の構造とダイナミクスは複雑である.
グーイ・チャップマン・スターンのような既存のモデルは離子表面相互作用に関する分子レベルの詳細が欠けている.
インターフェイス水に対するイオン効果を理解することは,化学反応性にとって極めて重要です.

研究の目的:

EDLの構造と動態に対するイオンの分子レベルの影響を明らかにする.
吸収されたイオンがシリカと水性のインターフェイスをどのように変化させるかを調査する.
インターフェースでのイオン効果を検知するためのスペクトロスコーピック方法を確立する.

主な方法:

組み合わせた時間解像度振動総周波数生成 (TR-vSFG) のスペクトロスコーピー
Ab initio DFTベースの分子動力学 (AIMD/DFT-MD) シミュレーション
インターフェースO-Hストレッチモードの振動寿命 (T1) の分析

主要な成果:

内層に吸収されたイオンは,ストーン層を水面から水間相互作用に移動させます.
不均質な水調整の景観は,2Dの水素結合 (2D-HB) ネットワークに変形します.
イオン吸附は,インターフェイスO-Hモードの振動寿命 (T1) を600fsから250fsまで短縮する.

結論:

イオン吸附は2D-HBの水ネットワークを促すことで表面水害性を誘導する.
TR-vSFGとDFT-MDのシミュレーションは,イオンコスモトロピク/カオトロピク効果の定量的な探査を提供します.
このアプローチは,水性の界面でのイオン誘発の水害性変化を明らかにします.

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