Field emission from polypyrrole-graphene composites synthesized by electrochemical deposition method

Field emission of graphene is usually limited by the surface morphology because the existing deposition methods lead to graphene flakes that lay flat on the substrate. To overcome this problem, we synthesized polypyrrole(PPy)-graphene composites by electrochemical deposition method. The graphene flakes are oriented at some angles on the PPy surface, leading to good field emission performance. This can be attributed to the enhanced local electric field at the tips and edges of the randomly vertical graphene flakes as well as the electrical conductivity enhancement due to the existence of PPy particles. Compared with the flat graphene sheets, the PPy-graphene composites show a better field emission performance, with a lower turn-on voltage and a larger current density. The results are of significance to the graphene based field emission device.