Researchers from Australia, Singapore, Japan, and the U.S. have developed a new technique to grow nearly defect-free graphene from the tea tree plant Melaleuca alternifolia.
The plant is used to make essential oils in traditional medicine. The researchers fabricated large-area graphene films from the tea tree oil in as little as a few seconds to a few minutes. On the other hand, current growth methods usually take several hours.
Furthermore, the new method also works at relatively low temperatures without any need for catalysts, and does not rely on methane or other nonrenewable, toxic, or explosive precursors.
Graphene has been grown from materials as diverse as plastic, cockroaches, Girl Scout cookies, and dog feces, and can theoretically be grown from any carbon source. However, scientists have been looking for a graphene precursor and growth method that is sustainable, scalable, and economically feasible.
Professor Mohan V. Jacob at James Cook University in Queensland, Australia, told Phys.org that the research realizes fabrication of good-quality, few-layer graphene from an environmentally friendly precursor.
The team used plasma-enhanced chemical vapor deposition to manufacture the graphene film. They fed the vaporized tea tree extract into a heated tube, much in the same way as done with methane gas in previous versions. As soon as they switched the plasma on using electrodes, the vapor was almost instantly transformed into a graphene film.
Graphene grown using this method has a particularly large surface area and long edges. The scientists estimate the total length of the edges in one square centimeter to be 1.6 miles. Graphene edges have a strong influence on the material’s overall properties, with long edges offering advantages for many applications, including battery electrodes and chemical sensors.
Furthermore, it is one of the most hydrophobic graphene samples yet. In general, hydrophobicity increases as 2D graphene attains more layers, becoming more 3D. In support of this relation, microscope images revealed 3D nanoscale features on the graphene’s surface that could be responsible for the strong hydrophobicity. These results suggest that the graphene film may be used to create various superhydrophobic coatings and surfaces for use in medical devices and textiles that repel water, reports Phys.org.
The researchers also expect the graphene films to be used in next-generation nonvolatile memory devices called memristors, which store memory in their levels of electrical resistance. They demonstrated this possibility by sandwiching a semiconductor between graphene and aluminum, creating a device that exhibits memristor like properties.
Going further, the team will focus on optimizing the material properties and implementing the material in various electronics applications.
Image courtesy of American Chemical Society.