Tuning Charge Transport in Voltage-Reduced Graphene Oxide through Defect Control and Quantum Confinement*

Graphene oxide (GO) is a versatile two-dimensional nanomaterial that is being explored for its tunable electrical, optical, and chemical properties. This tunability is afforded by reduction which removes oxygen-containing functional groups, restores the sp² carbon lattice, and converts the electrically insulating material to one that is conducting. Here, we use voltage reduction, a simple and environmentally benign procedure, to manipulate the electrical properties of GO from insulating to conducting, and potentially semiconducting. A low-defect form of GO, oxo-G, was synthesized and voltage-reduced to produce a highly conductive graphene derivative. Variable temperature electrical resistance measurements reveal a transition from hopping transport to a temperature-stable resistance over a broad temperature range, making this material promising for use in sensors and other applications that require temperature-stable performance. Nanopatterning was also employed, by using a conductive atomic force microscope probe to initiate voltage reduction. Preliminary data suggests possible transport gap opening due to quantum confinement.