Elucidation of solvent reorganization process during electrochemical reactions in ionic liquids

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04992
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 32010:Fundamental physical chemistry-related
• Research Institution: Nagoya Institute of Technology
• Principal Investigator: Motobayashi Kenta 名古屋工業大学, 工学(系)研究科(研究院), 准教授 (60609600)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: イオン液体 / 電極界面構造 / 電気化学 / 金属電析 / マーカス理論 / 表面増強赤外吸収分光法

Outline of Final Research Achievements

The aim of this study was to understand the contribution of solvent rearrangement processes to electrochemical reactions in ionic liquids. Direct observation of the solvent rearrangement processes at the electrode interface during the metal electrodeposition reactions were performed under different conditions of temperature, metal species, and ionic liquid cations. The results showed that under all conditions, the solvent rearrangement on the electrode and metal electrodeposition started at identical potentials. This can be ascribed to the hindrance of the rearrangement of the excess solvent anions which are detached from metal cations due to electrodeposition in the periodic ordered charge arrangement at the interface. It is shown that the solvent rearrangement treated in Marcus theory should include the rearrangement toward the electrode surface.

Free Research Field

表面界面科学

Academic Significance and Societal Importance of the Research Achievements

電子移動反応を取り扱う上で一番の基礎となる理論、マーカス理論について、イオン液体中の電気化学反応を取り扱うにあたっての適用方法を開拓することができた。一般的な電気化学が前提とする希薄電解質溶液とは異なる環境への適用方法を見出したことに大きな学術的意義がある。またこの結果は、イオン液体中の金属電析反応において、エネルギー効率低下の原因となる特有の過電圧の発生原因をも示唆している。様々な化学種のめっきに使えるイオン液体に対して、エネルギー効率向上に向けて有益な基礎情報が得られたことに、社会的意義がある。