Synthesize and characterization of graphene nanosheets with high surface area and nano-porous structure

•High quality with high specific surface area graphene was synthesized via heat treatment water intercalated graphene oxide.•The best temperature for heat treatment method was found.•Water intercalated graphene oxide was expansion and exfoliation by chemical.•The most suitable time reaction for chemical reaction was estimated.

A few-layer graphene was obtained by the expansion and exfoliation of water-intercalated graphene oxide via heat treatment in nitrogen environment in the temperature range of 200-1000 °C. Graphene which was synthesized at 800 °C (GT800) had a higher quality than other temperatures. This graphene has a high specific surface area (560.6 m2 g−1) and nano-porous structure. However, as for the purpose of comparison, graphene was synthesized with a colloidal suspension of exfoliated graphene oxide sheets in water with hydrazine hydrate in various reaction times (12, 24 and 36 h). This method has obtained a six-layer graphene and graphene that was synthesized during 24 h reaction with hydrazine hydrate (GC24) had a higher quality in comparison with the other products. The GC24 had 195.97 m2 g−1 specific surface area and nano-porous structure. The as-synthesized graphene were then characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) as well as BET measurements. The results demonstrated that this low-cost method for few-layer grapheme, e.g. three-layers, fabrication is reliable and promising.