Fabrication of nano-onion structured graphene films from Citrus sinensis extract and their wetting and sensing characteristics.

Graphene and its derivatives have acquired substantial research attention in recent years due to a wide range of potential applications. Implementing sustainable technologies for fabricating these functional nanomateri-als is becoming increasingly apparent, and therefore a wide spectrum of naturally derived precursors have been identified and reformed through various established techniques for the purpose. Nevertheless, most of these methods could only be considered partially sustainable due to their complexity as well as high energy, time, and resource requirements. Here we report the fabrication of carbon nano-onion interspersed vertically oriented multilayer graphene nanosheets through a single-step, environmentally benign radio frequency plasma-enhanced chemical vapor deposition process from a low-cost carbon feedstock, the oil from the peel of Citrus sinensis fruit. Citrus sinensis oil is a volatile aroma liquid principally composed of non-synthetic hydrocarbon limonene. Transmission electron microscope studies on the structure unveiled the presence of hollow quasi-spherical carbon nano onion-like structures incorporated within graphene layers. The as-fabricated nano onion incorporated graphene films exhibited highly hydrophobic nature showing a water contact angle of up to 1290. The surface energies of these films were in the range of 41 to 35 mJ.m-2. More-over, a chemiresistive sensor directly fabricated using the C. sinensis derived onion structured graphene showed a p-type semiconductor nature and a promising response to acetone at room temperature. With its unique morphology, surface properties, and electrical characteristics, this material is expected to be useful for a wide range of applications.