Microabrasive-assisted exfoliation of graphene from graphite

• Main Authors: Velasquez, Joan Candice P., Tan, Andreneve L., Sabio, Erwin M., Browning, Nigel, Querebillo, Christine U., Somintac, Armando, Salvador, Arnel, Enriquez, Erwin P.
• Format: text
• Published: Animo Repository 2012
• Subjects: Graphene—Abrasion resistance; Graphene —Mechanical properties; Chemical Engineering
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/8581
• Institution: De La Salle University

Since its discovery in 2004, graphene1 has been at the center of nanotechnology research mainly due to its mechanical stability, optical transparency, and superior electrical conductivity. These extraordinary properties make it a promising material for optoelectronic applications2. In this study, a top-down approach towards improved graphene synthesis was investigated. Specifically, liquid phase exfoliation with the aid of alumina microabrasives was carried out. Different weight ratios of graphite and microabrasive were sonicated for two hours in N-methyl pyrrolidone (NMP), and the mixture was centrifuged for 1.5 hours at 13,000 rpm. Control experiments were done without the microabrasive. Enhanced yields of graphene dispersions in (NMP) have been achieved with the aid of the microabrasives wherein enhanced exfoliation of graphite formed stable graphene flakes dispersions in NMP as confirmed through transmission electron microscopy. Different sizes of α-alumina were used as microabrasives. It was observed that for a given type of abrasive, the yield of graphene exfoliated from graphite increased except for the case when the mean size of the abrasive used was very small--0.05 micron у-alumina. For the 1 µm α-alumina abrasive, there was increase in the yield as manifested in the darker supernatant obtained. The graphene yield was quantified from the UV-visible absorption spectra and thermogravimetric analysis. The absorbance at wavelength λ = 270 nm was used and plotted against the mass ratio of graphene to abrasive. The trends for the 1 µm and 5 µm alumina showed a general increase in yield in graphene flakes (up to nearly 100% increase versus the control), which plateaus at around 1:4 for the 5 µm abrasive, but dipped again to low yields at 1:8 ratio for the 1 µm abrasive.