Probing the electric double-layer capacitance in a Keggin-type polyoxometalate ionic liquid gated graphene transistor.

A variety of device applications has been proposed using polyoxometalate-based ionic liquids. However, the assembly of large polyoxometalate ions on surfaces and the associated interfacial properties are not well understood, particularly since the assembly is influenced by steric effects and stronger ion-ion interactions. In this study, graphene transistors gated with a polyoxometalate-based ionic liquid were probed with in situ Raman spectroscopy and charge transport studies.

Estimating the thermal expansion coefficient of graphene: the role of graphene-substrate interactions.

The temperature-dependent thermal expansion coefficient of graphene is estimated for as-grown chemical vapor deposited graphene using temperature-dependent Raman spectroscopy. For as-grown graphene on copper, the extent of thermal expansion mismatch between substrate and the graphene layer is significant across the entire measured temperature interval, T  =  90-300 K. This mismatch induces lattice strain in graphene.

Mechanical tearing of graphene on an oxidizing metal surface.

Graphene, the thinnest possible anticorrosion and gas-permeation barrier, is poised to transform the protective coatings industry for a variety of surface applications. In this work, we have studied the structural changes of graphene when the underlying copper surface undergoes oxidation upon heating. Single-layer graphene directly grown on a copper surface by chemical vapour deposition was annealed under ambient atmosphere conditions up to 400 °C.