Unprecedented expansion of graphite with low power laser for high-quality liquid phase exfoliated graphene

As graphene and related materials increasingly integrate into various industries, producing high-quality graphene sheets on a large scale becomes crucial. Here, we present a unique approach to the large-scale production of graphene through laser-assisted graphite expansion followed by ultrasonic exfoliation. The present method utilizes laser technology to significantly expand graphite, achieving an expansion rate of 800 mL g^-1 with a deficient energy consumption of just two watts laser. The graphene produced via ultrasonication of expanded graphite samples exhibited high quality (I_D/I_G) ~ 0.13 and a few layers with a (I_2D/I_G) ~ 0.52. Free-standing films with different thicknesses (11-69 µm) were successfully prepared through filtration, reaching significant electrical conductivity up to (~ 1707 S cm^-1). The as-prepared graphene films are further explored for electromagnetic interference (EMI) shielding. The highest shielding effectiveness (SE) was recorded for the graphene film with a thickness of 69 µm, reaching a value of ~ 72 dB. Meanwhile, the graphene film with an 11 µm thickness achieves the highest absolute effectiveness (SSE/t) of ~ 58,666 dB cm² g^-1_, surpassing most current graphene and MXene films, which typically present values in the range of 10,000 to 40,000 dB cm² g^-1. This present laser-assisted expansion incorporating a sonication exfoliation strategy paves a new way to produce graphene on a large scale.