rGO

Reduced graphene oxide (rGO) is a form of graphene oxide that has been chemically, thermally, or electrochemically reduced to remove part of the oxygen-containing groups and restore part of the carbon lattice. It is a two-dimensional carbon material derived from graphite oxide in which some oxygen functionalities remain and structural defects persist. Compared with pristine graphene, rGO typically exhibits lower electrical conductivity and a more disordered structure, but it retains a high surface area and good processability, making it useful in various applications.

Preparation methods include chemical reduction with agents such as hydrazine, sodium borohydride, hydroquinone, or ascorbic acid to remove epoxy, hydroxyl, and carboxyl groups from graphene oxide. Thermal reduction involves rapid heating of GO at high temperatures in inert or reducing atmospheres, which decomposes oxygen groups and causes gas evolution. Electrochemical reduction applies a reductive potential to GO-coated electrodes in an electrolyte. The choice of method influences residual oxygen content, defect density, and properties such as conductivity and dispersibility.

Properties of rGO include improved electrical conductivity relative to GO but generally lower than pristine graphene. It contains residual oxygen groups and vacancy-type defects that affect work function, chemical reactivity, and interlayer interactions. rGO can be produced in few-layer forms and tends to restack unless well dispersed or functionalized. Characterization commonly uses XPS to quantify carbon-oxygen content, Raman spectroscopy to assess graphitic disorder (D and G bands), and microscopy techniques to observe morphology.

Applications span energy storage, including supercapacitors and Li- or Na-ion batteries; conductive additives and reinforcement in polymer and ceramic composites; catalysis and electrocatalysis; chemical and biological sensing; and membranes for selective separation and desalination. Research continues to optimize reduction strategies to balance conductivity with functional group availability for specific uses.