Highly crystalline selectively oxidized graphene for supercapacitors

Graphene oxide (GO) is usually regarded as a graphene precursor for scalable synthesis, mainly due to its aqueous processability from introducing oxygen functionalities. Nevertheless, the precise control of graphene's oxidation degree to obtain a good balance between dispersion stability and crystallinity remains challenging. This study describes a simple and practical approach to synthesize a new graphene-based material called selectively oxidized graphene (SOG), which combines the advantages of graphene and GO. SOG shows water stability of −36.2 mV, a C/O ratio of 5.2, and most importantly, a very high crystallinity degree, with an ID/IG of 0.414. The synthesized SOG exhibits an ultra-low optical band gap of 0.04 eV, 75 times lower than GO. Moreover, the electrical resistance, 1.12 KΩ/sq is nine orders of magnitude smaller than GO. Additionally, it also shows promising 3-electrode capacitance with an improvement above 400 % compared to exfoliated graphene. A Swagelok-based supercapacitor was fabricated to analyze the feasibility of SOG for energy storage applications, which exhibited remarkable characteristics such as ∼ 93F g−1 capacitance and ∼ 99.8 % retention after 10,000 cycles. The characteristics of SOG ensure that this new material is promising for applications in organic electronics.