Exfoliation of graphite in various electrolytes and preparation of graphene films via electrochemical approach

Graphene, exhibiting superior mechanical, thermal, optical and electronic properties, has attracted great interest. Anodic exfoliation of graphite has emerged as an attractive method to access graphene nanosheets in large quantities. In this work, electrochemical exfoliation used to synthesize graphene oxide (GO) flakes in different aqueous electrolytes with various concentrations and voltages is reported. The prepared GO powders were subjected to different characterizations and (NH4)2SO4 was found the best suited starting material for preparation of graphene thin films. The exfoliated graphene sheets exhibited lateral size of about 2 μm and contained only a few graphene layers. The graphene powder was spin-coated on glass substrates under different conditions such as graphene suspension concentration, spin time and speed. Then the electrical and optical properties of the prepared samples were studied as functions of chemical reduction and combination of chemical and thermal reduction treatments. It was noted that applying the later treatment, resulted in optimal graphene films with high transmittance of 73% and low sheet resistance of 22.31 kΩ/sq.