Insulator to Semimetal Transition in Graphene Oxide

Transport properties of progressively reduced graphene oxide (GO) are described. Evolution of the electronic properties reveals that as-synthesized GO undergoes insulator−semiconductor−semimetal transitions with reduction. The apparent transport gap ranges from 10 to 50 meV and approaches zero with extensive reduction. Measurements at varying degrees of reduction reveal that transport in reduced GO occurs via variable-range hopping and further reduction leads to an increased number of available hopping sites.