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ガス相における水性ナノドロップの減少によって測定された絶対標準水素電極電位
William A Donald1, Ryan D Leib, Jeremy T O'Brien
1Department of Chemistry, University of California, Berkeley, California 94720-1460, USA.
Journal of the American Chemical Society
|February 22, 2008
まとめ
研究者は,ガス相ナノドロップ実験を用いて溶液中のリドックスカップルの絶対的還元エネルギーを決定した. このアプローチにより,標準水素電極 (SHE) の絶対値は,自由電子に対して4.2 ± 0.4Vであった.
科学分野:
- 電気化学 電気化学について
- 物理化学 物理化学
- コンピューティング・ケミストリー
背景:
- 半電池の電気化学的電位は相対的であり,0Vの標準水素電極 (SHE) に参照される.
- 溶液における絶対的な電気化学的ポテンシャルスケールの確立は,普遍的なコンセンサスのない課題であり続けています.
- 最初の溶解殻を超えた溶媒効果の正確なモデリングは困難です.
研究 の 目的:
- 水溶液中の酸化還元カップルの絶対還元エネルギーを実験的に決定する.
- ガス相と溶液相のリドックス化学を橋渡しすることで,絶対的な電気化学のスケールを確立する.
- 標準水素電極 (SHE) の絶対値を得る.
主な方法:
- 金属イオンを含むガス相ナノドロップによる電子捕獲によるイオン-電子再結合エネルギーの測定 ([M(NH3) 6 3+とCu 2+).
- 再結合エネルギーを定量化するために,減少した前駆体から失われた水分子の数を利用する.
- ナノドロップの溶解エネルギーと溶液相エントロピーのための実験データをボーン理論と組み合わせる.
主要な成果:
- 大量水溶液中の特定の酸化還元カップルの絶対還元エネルギーを計算した.
- 標準水素電極 (SHE) の絶対値は,自由電子に対して 4.2 ± 0.4 V と決定されました.
- この方法は,2つの溶解殻を超えた溶媒効果を本質的に含んでいますが,これはモデル化に困難です.
結論:
- 開発された方法は,絶対的な電気化学スケールの確立のための実行可能なアプローチを提供します.
- この実験技術は,ガス相と溶液相のリドックス化学を橋渡ししています.
- 将来の精製により,不確実性は0.1V以下に低下し,メソッドの有用性を高めることができます.
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