  Graphene oxide (GO), the functionalized graphene with oxygenated groups
(mainly epoxy and hydroxyl), has attracted resurgent interests in the past
decade owing to its large surface area, superior physical and chemical
properties, and easy composition with other materials via surface functional
groups. Usually, GO is used as an important raw material for mass production of
graphene via reduction. However, under different conditions, the coverage,
types, and arrangements of oxygen-containing groups in GO can be varied, which
give rise to excellent and controllable physical properties, such as tunable
electronic and mechanical properties depending closely on oxidation degree,
suppressed thermal conductivity, optical transparency and fluorescence, and
nonlinear optical properties. Based on these outstanding properties, many
electronic, optical, optoelectronic, and thermoelectric devices with high
performance can be achieved on the basis of GO. Here we present a comprehensive
review on recent progress of GO, focusing on the atomic structures, fundamental
physical properties, and related device applications, including transparent and
flexible conductors, field-effect transistors, electrical and optical sensors,
fluorescence quenchers, optical limiters and absorbers, surface enhanced Raman
scattering detectors, solar cells, light-emitting diodes, and thermal
rectifiers.
