Acid-less direct gram scale exfoliation of graphite to partially oxidized graphene

Abstract

All methods to synthesize graphene oxide on a large scale utilize a strongly acidic medium. Graphene oxide (GO) to reduced graphene oxide (rGO) conversion, i.e., obtaining widespread sp2–sp2 hybridized carbon allotropes is a laborious and tedious process. Herein, we report an innovative one-step method, through which we fabricate ‘partially oxidized graphene’ on a gram scale directly from graphite powder, without using any acids. The emergence of the (002) XRD peak, band gap (Eg ~ 1.42 ± 0.01 eV), and carbon-to-oxygen (C/O) ratio of 3.67 validate the direct POG phase formation without any reduction step. Raman (ID/IG ~ 0.80 ± 0.06) and AFM studies reveal the less defective and bi- to few-layer character of POG sheets of thickness ca. 1.59 ± 0.14 nm. The measured conductivity of the POG material (9.22 ± 0.04 S/cm) is found to be higher than the conductivity of the rGO using the standard method (0.30 ± 0.03 S/cm). The zeta potential study suggests a good stability of the POG aqueous dispersion. Furthermore, the proposed method is efficient (2–3 h), safe, and renders a higher yield (77%) than many conventional methods (40–70%) for GO preparation. This offers a promising source for conductive electrodes, carbon paste, and more.