Solid-Like Ordering of Imidazolium-Based Ionic Liquids at Rough Nanostructured Oxidized Silicon Surfaces

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Ionic liquids (ILs) are increasingly used as electrolytes in devices with nanostructured electrodes.
• Confinement of ILs in porous matrices offers solutions for packaging, leakage, and portability challenges.
• Understanding IL-solid interactions is crucial for optimizing performance in nanoporous devices.

Purpose of the Study:

• To investigate the effects of surface spatial confinement on the properties of imidazolium-based ionic liquids.
• To explore the interaction between [Bmim][NTf2] ionic liquid and a nanostructured oxidized silicon surface (ns-SiO2).
• To understand how confinement influences the morphological and mechanical properties of ionic liquids.

Main Methods:

• Surface spatial confinement of [Bmim][NTf2] ionic liquid on a cluster-assembled, nanostructured, rough, oxidized silicon (ns-SiO2) surface.
• Atomic force microscopy (AFM) was employed to investigate the morphological and mechanical changes.

Main Results:

• Spatial confinement induced local rearrangement of [Bmim][NTf2] into ordered, layered, stiff, solid-like domains.
• These solid-like domains coexist with and are embedded within the liquid ionic liquid film.
• Interfacial layering was observed, suggesting complex behavior at the IL-electrode interface.

Conclusions:

• The behavior of IL-electrode interfaces in photoelectrochemical devices can be more complex than assumed.
• The observed interfacial layering indicates potential deviations from a stable liquid phase electrolyte model.
• These confinement effects may be amplified within the bulk nanoporous matrix of devices.