Atomic force microscopy probing interactions and microstructures of ionic liquids at solid surfaces.

Ionic liquids (ILs) are room temperature molten salts that possess preeminent physicochemical properties and have shown great potential in many applications. However, the use of ILs in surface-dependent processes, energy storage, is hindered by the lack of a systematic understanding of the IL interfacial microstructure. ILs on the solid surface display rich ordering, arising from coulombic, van der Waals, solvophobic interactions, , all giving near-surface ILs distinct microstructures.

On the ionic liquid films 'pinned' by core-shell structured FeO@carbon nanoparticles and their tribological properties.

A strongly 'pinned' ionic liquid (IL, [BMIM][PF6]) film on a silicon (Si) surface via carbon capsuled Fe3O4 core-shell (Fe3O4@C) nanoparticles is achieved, revealing excellent friction-reducing ability at a high load. The adhesion force is measured to be ∼198 nN at the Fe3O4@C-Si interface by the Fe3O4@C colloidal AFM tip, which is stronger than that at both Fe3O4@C-Fe3O4@C (∼60 nN) and IL-Si (∼10 nN) interfaces, indicating a strong 'normal pin-force' towards the Si substrate. The resulting strengthened force enables the formation of lateral IL networks via the dipole-dipole attractions among Fe3O4 cores.

Graphene tailored by FeO nanoparticles: low-adhesive and durable superhydrophobic coatings.

This study reports stable superhydrophobic FeO/graphene hybrid coatings prepared by spin coating of the FeO/graphene/PDMS mixed solution on titanium substrates. By tailoring graphene sheets with FeO nanoparticles, the superhydrophobicity of graphene platelets was largely enhanced with a water contact angle of 164° and sliding angle <2°. FeO nanoparticles interact with FLG sheets Fe-O-C covalent link, to form a graphene micro-sheet pinned strongly by nano-sized FeO.