Electrochemical reduction of oxygen-functional-group-controlled graphene oxide for high carrier mobility

Graphene oxide (GO) contains multiple oxygen functional groups and nano-sized pores that limit the electrical performance of reduced GO (rGO). Here, we elucidate the chemical stability and electrochemical reduction behaviour of an oxygen-functional-group-controlled GO (epGO) with a highly ordered basal plane and without nano-sized pores. The epGO exhibited significantly higher stability than conventional GO (H-GO) prepared by Hummers' method in both acidic and basic solutions, retaining its uniform C-O-C functionality. XPS and isotope-substituted FT-IR measurements revealed that electrochemical reduction of epGO proceeds predominantly through defect-free pathways that generate CC bonds with minor formation of C-OH groups. As a result, rGO derived from epGO maintains a well-ordered honeycomb lattice, in contrast to the defect-rich structure produced by conventional methods. These structural advantages enable the electrochemically reduced epGO in acidic solution at room temperature to achieve higher carrier mobilities up to 146 cm² V^-1 s^-1, surpassing those previously reported for rGO obtained by thermal reduction at ultra-high temperatures (over 1000 °C). This study strongly demonstrates electrochemical reduction of epGO as an effective, low-energy route for producing high-quality rGO for electronic applications.