Researchers affiliated with UNIST (Ulsan National Institute of Science and Technology) in Korea have engineered a new type of carbon nanomaterials, reportedly capable of changing shapes and colors depending on the type of solvents used. Such materials have attracted much attention thanks to their unique optical properties and structures.
The research team has presented a unique design and synthesis of hybrid carbon nanosheets (CNSs), which show a strong solvatochromic behavior (the ability of a chemical to change color due to a change in solvent polarity) with wide color tunability ranging from blue to orange and even to white in various solvents. This unique hybrid CNS features clusters of carbon nanorings on the surface of graphene-oxide (GO) nanosheets as the product of the hydrothermal reaction of small molecular precursors in the presence of GO nanosheets. Moreover, under UV and visible-light excitation, the hybrid CNS exhibits tunable emission spanning the wide range of colors in a series of solvents with different polarities.
According to the research team, this interesting spectroscopic behavior is found to stem from hydrogen-bonding interactions between CNS and solvents, which eventually induce the morphological transition of CNS from 2D sheets to 3D crumpled morphologies, affecting the lifetimes of emissive states.
"This is one of the first studies to show clearly that the shape of CNS varies depending on the solvents," says the team. "Through this research, we hope to improve the physical characteristics of hybrid materials and expand its application fields."