Simple and rapid cleaning of graphenes with a ‘bubble-free’ electrochemical treatment

Abstract

We herein report a remarkably simple and fast bubble-free electrochemical (EC) treatment process to clean single-layer graphenes (SLGs) that become unintentionally doped during their transfer process. For the EC-treatment process, linear sweeping voltages with respect to a Ag/AgCl reference electrode are applied to the SLG used as a working electrode within non-faradaic regions in a non-aqueous electrolyte. In the EC treatment, we adjust the sweeping voltage ranges and find that treatment at negative voltages for 10 min induces the desorption of not only the polymer scaffold residue but also the etchant residues remaining on the SLG surface via the Coulombic repulsion mechanism between the residues and the SLG electrode. Accordingly, the EC-treated SLG is de-doped and begins to recover its intrinsic electrical properties, showing a Dirac point energy of ∼4.4 eV, a work function of ∼4.6 eV, and high carrier mobility levels, comparable to the intrinsic properties of graphene monolayers. This study shows the potential to revolutionise the cleaning technique of residue on SLGs and demonstrates that bubble-free EC-treated SLGs can be used to fabricate reliable and controllable transparent SLGs for advanced graphene-based electronic devices.