One-dimensional Pt nanofibers formed by the redox reaction at the ionic liquid|water interface

Abstract

Pt nanofibers have been prepared with a redox reaction occurring spacio-selectively at the liquid-liquid interface between a highly hydrophobic ionic liquid (IL) and water (W), which has been utilized as two-dimensional reaction field. The preparation is conducted based on the concept of the coupling between ion transfer (IT) and electron transfer (ET) across the IL|W interface, which previously enabled direct formation of dendritic Au nanofibers at the IL|W interface (Chem. Commun., 2015, 51, 13638). The successful preparation of Pt nanofibers has manifested the generality of the IL|W interface method for the formation of metal nanofibers. Electrochemical measurements at the IL|W interface have confirmed that IT of PtCl42− from W to IL is actually coupled with ET between PtCl42− initially dissolved in W and decamethylferrocene in IL, leading to the spontaneous formation of Pt nanofibers at the IL|W interface. Herein, IT of PtCl42− ions from W to IL not merely neutralizes the excess charges generated in each liquid phase by ET, but also provides PtCl42− into IL as reactants for the growth of Pt nanofibers that takes place at the IL side of the IL|W interface. The electrocatalytic activity of the Pt nanofibers in oxygen reduction reaction (ORR) has also been evaluated.