Converting the Conducting Behavior of Graphene Oxides from n-Type to p-Type via Electron-Beam Irradiation.

We studied the effects of electron-beam irradiation (EBI) on the structural and gas-sensing properties of graphene oxide (GO). To understand the effects of EBI on the structure and gas-sensing behavior of irradiated GO, the treated GO was compared with nonirradiated GO. Characterization results indicated an enhancement in the number of oxygen functional groups that occurs with EBI exposure at 100 kGy and then decreases with doses in the range of 100-500 kGy. Data from Raman spectra indicated that EBI could generate defects, and NO2-sensing results at room temperature showed a decreased NO2 response after exposure to EBI at 100 kGy; further increasing the dose to 500 kGy resulted in p-type semiconducting conductivity. The conversion of GO from n-type to p-type via EBI is explained not only through the generation of holes but also the variation in the amount of residual functional groups, including carboxyl (COOH) and hydroxyl groups (C-OH). The obtained results suggest that EBI can be a useful tool to convert GO into a diverse range of sensing devices.