Sonication-enhanced microfluidization for low-cost graphite exfoliation

This study presents an efficient low-cost alternative to the microfluidization process, enhanced by sonication, for the production of highly conductive exfoliated graphite thin films. Diverging from previous works utilizing short, small-diameter capillaries for graphite exfoliation at elevated pressures (typically exceeding 1000 bar), our approach employs a significantly larger diameter and substantially longer serpentine tube at lower pressure levels (300 to 600 bar) for sonication-assisted exfoliation. Comprehensive characterizations through SEM, Raman spectroscopy, profilometry, AFM, XRD, and FTIR confirms high quality of produced nanomaterial. Taking advantage of the synergistic effects of sonication and high-shear processing, we achieved efficient exfoliation of graphite flakes at 600 bar, resulting in nanographite flakes with a peak thickness approaching 60 nm. Furthermore, suspensions of these nanographite flakes were utilized to fabricate flexible, highly conductive films through a vacuum filtration technique, demonstrating electrical conductivity levels as low as 0.0032 Ω.cm. The larger cross-section of the capillary used here enables much faster processing of denser micrographite suspensions, preventing capillary obstruction even with much larger micrographites (20 µm lateral size).