Local electrochemical reactivity of single layer graphene deposited on flexible and transparent plastic film using scanning electrochemical microscopy

Abstract The local electrochemical reactivity of single layer graphene/ethylene vinyl acetate/polyethylene terephthalate (EVA/PET) plastic film was investigated using scanning electrochemical microscopy (SECM). Interestingly, depending on the reducing or oxidizing power of the selected redox mediator, the SECM response changes from slow (case of electron donor) to fast (case of electron acceptor) electron transfer rate. Furthermore, the as-prepared graphene was modified through the electrochemical reduction of p-nitrophenyl diazonium leading to the attachment of thin organic layer. The SECM investigations demonstrate that the attached nitrophenyl layer accelerates the heterogeneous electron transfer process when using electron donor as redox probe. The overpotential transition from slow to fast electron transfer was shifted by 400 mV, when compared to the un-modified graphene, suggesting the increase of the work function of the modified graphene. However, further functionalization with a Pt nanoparticles selectively makes the substrate as “insulating-like” layer toward electron acceptor species. Overall, depending on the deposited material and the used redox probe (electron donor or acceptor) the SECM investigations reveals that the properties of the graphene change from p to n type doping. This technique can be applied to the electrochemical investigations of graphene supported insulating, flexible and transparent material.