Hydrophobic alkylphosphonium ionic liquid for electrochemistry at ultramicroelectrodes and micro liquid vertical bar liquid interfaces

作者：Stockmann Tom J; Zhang Jing; Wren J Clara; Ding Zhifeng^*

来源：Electrochimica Acta, 2012, 62: 8-18.

DOI：10.1016/j.electacta.2011.10.087

• Room temperature ionic liquid (RTIL)
• Micro liquidiliquid interfaces
• Ultramicroelectrode Electron transfer
• Ion transfer

Combining a large asymmetric alkylphosphonium cation, trihexyltetradecylphosphonium, with the tetrakis(pentafluorophenyl)borate anion affords a very hydrophobic room temperature ionic liquid (RTIL) possessing a melting point below room temperature. The viscosity and conductivity of this RTIL have been measured along with cyclic voltammetry (CV) of the ferrocenefferrocenium redox couple at an ultramicroelectrode from 25 to 90 degrees C. The RTIL demonstrates a polarized potential window (PPw) at the watern interface as large as 0.8 V; indicating the large hydrophobicity of its component ions. Simple ion transfer (IT), at the micro waterilL interface (25 mu m in diameter) housed at the tip of a micropipette was calibrated using the tetraphenylarsonium tetraphenylborate TATB assumption. The Galvani transfer potentials of several IT reactions at the interface were determined. It was discovered that large peak-to-peak separation in CVs obtained at the solid-liquid and liquid-liquid junction was mainly due to the slow electron transfer (ET) and IT kinetics. This is confirmed by overlapping experimental and theoretical CVs obtained from finite element analysis simulations. Standard rate constants (k) of 5 x 10(-4) cm s(-1) were garnered at these interfaces.

• 出版日期2012-2-15