Solar Assisted Expansion of Graphite Flakes for an Effective Exfoliation of Graphene Sheets

When and Where

Nov 27, 2023
8:00pm - 10:00pm

Hynes, Level 1, Hall A

Presenter

Shanavas Shajahan

Rami Elkaffas

Yarjan Abdul Samad

Co-Author(s)

Shanavas Shajahan¹,Rami Elkaffas¹,Yarjan Abdul Samad^1,2

Khalifa University of Science and Technology¹,University of Cambridge²

Abstract

Shanavas Shajahan¹,Rami Elkaffas¹,Yarjan Abdul Samad^1,2

Khalifa University of Science and Technology¹,University of Cambridge²

Synthesis of scalable monolayer or few-layered graphene sheets is challenging due to the complex production processes [1-3]. Liquid phase exfoliation is considered as one of the most feasible techniques to produce industrially scalable [1] defect-free graphene sheets [4,5]. In ultrasonic exfoliation techniques, long exposure (up to 48 hours) [6] of graphene sheets to the ultrasonic waves considerably decreases its lateral size [7], which limits the mechanical and electrical properties of produced graphene [8]. In this study, we successfully achieved the preparation of graphene sheets with high (4-5 mm) lateral sizes by pre-expanding the graphite through solar-assisted expansion process [9]. The graphite flakes with a lateral size of about 600 μm are intercalated with the perchloric acid (HClO4) at 120 °C for 30 min to prepare stage II intercalated graphite (S2IG). In the S2IG, HClO4 is intercalated in between every two layer of graphene sheets, which can be confirmed through Raman analysis [10]. The S2IG is expanded by focusing sunlight on its surface using a simple magnification lens (diameter = 75 mm, focal length = 10 cm). The solar expansion process (SEP) resulted in the formation of expanded graphite with an expansion ratio of about 1:240 (graphite: solar expanded graphite) and lateral size of solar expanded graphite is about 400 μm, which is similar to the intercalated graphite flakes. The solar expanded graphite is exfoliated through probe sonication (500-watt, 20 kHz) for 20 min to obtain few-layer graphene sheets [11]. Raman analysis confirms the formation of defect-free solar expanded graphite as well as few-layer graphene sheets. The obtained results clearly show that the lateral size of graphene sheets can be enhanced by pre-expanding the graphite sheets through solar irradiation before the probe sonication process. *Corresponding authors Dr Yarjan Abdul Samad ([email protected]) Dr Shanavas Shajahan ([email protected]) References 1. A Zurutuza et al., Nat. nanotech., 9 (2014), 730. 2. EJ Siochi et al., Nat. nanotech., 9 (2014), 745. 3. KR Paton et al., Nat. mater., 13 (2014), 624. 4. Z Li et al., ACS nano, 14 (2020), 10976. 5. Y Hernandez et al., Nat. nanotech., 3 (2008), 563. 6. M Sandhya et al., Ultrason. Sonochem., 73 (2021), 105479. 7. P Turner et al., Sci. rep., 9 (2019), 8710. 8. L Lin et al., Nat. mater., 18 (2019), 520. 9. L Zhuet al., Mater. Chem. Phys., 137 (2013), 984. 10. Li Yuqi et al., Chem. Soc. Rev., 48 (2019), 4655. 11. AV Tyurnina et al., Carbon 168 (2020), 737.