Higher Ultrasonic Frequency Liquid Phase Exfoliation Leads to Larger and Monolayer to Few-Layer Flakes of 2D Layered Materials

Among the most reliable techniques for exfoliation of two-dimensional (2D) layered materials, sonication-assisted liquid-phase (LPE) is considered as a cost-effective and straightforward method preparing graphene its 2D inorganic counterparts at reasonable sizes acceptable levels defects. Although there were rapid advances in this field, effect outcome sonication frequency are poorly understood often ignored, resulting low efficiency. Here, we demonstrate that simple mild bath higher power positively contributes to thickness, size, quality final exfoliated products. We show monolayer flakes can be directly from graphite using ethanol solvent by increasing 37 80 kHz. The statistical analysis shows ?77% measured have thickness below three layers with an average lateral size 13 ?m. approach works digenite (Cu9S5) silver sulfide (Ag2S), thus indicating technique applied other materials obtain high-quality few-layered flakes. This effective facilitates formation monolayer/few transition metal chalcogenides wide range applications.