Synthesis of free standing conducting graphene paper by thermal reduction of graphene oxide paper.

Graphene is one atom thick two dimensional material with unusual mechanical, electrical, thermal and optical properties. Graphene, on larger scale is produced through reduction of graphene oxide which in turn is synthesized by chemical oxidation of graphite. Generally large area graphene oxide paper can be easily fabricated by solution filtration process, spin casting method and Langmuir-Blodgett assembly. In present study graphene oxide was synthesized by modified Hummers method. Free standing graphene oxide paper (GOP) was developed by simple drying of graphene oxide suspended in water followed by reduction by thermal treatment to synthesize free standing conducting graphene paper (Thermally Reduced Graphene Paper, TRGP). Thermal reduction was carried out for 30, 60, 90 and 120min and samples referred as TRGP_30, TRGP_60, TRGP_90 and TRGP_120 respectively. XRD results show decrease in inter layer spacing (d002) from 0.87 nm to ∼0.35 nm after reduction of GO paper. This shows gradual removal of oxygen functionalities and adsorbed water during reduction. Meanwhile the size of sp² domains of graphene also decrease as studied by Raman spectroscopy. SEM results also show change in morphology of thermally reduced graphene paper. The electrical conductivity of reduced graphene paper increases from 2.8 × 10-2 S/m for as such graphene oxide paper to 1.3 × 102 S/m for graphene paper. [ABSTRACT FROM AUTHOR]