Engineering the electrical and optical properties of graphene oxide via simultaneous alkali metal doping and thermal annealing

In order to extend the application of graphene oxide (GO) in the area of electronic industries, enhancing the electrical properties of GO as a cost-effective alternative for graphene seems mandatory. Engineering the electrical properties of GO can be achieved in two different approaches: the oxygen functional group reduction and doping GO with chemical dopants. Here, both approaches were utilized to tune the electrical properties of GO toward its application as cathode; first, GO was doped with alkali metal dopants, and later, the doped samples were thermally reduced. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy were utilized to study the chemical composition of the doped samples. The even distribution of the dopants on the GO surface presented via the EDX elemental map, with no sign of particle development. After doping GO with alkali metals followed by thermal reduction, the sheet resistance of the doped samples was decreased from 311.0 kΩ/sq to as low as 32.1 kΩ/sq. Moreover, the optical properties of GO were effectively engineered via the different doping agents. The ultra-violet photoelectron spectroscopy showed that the shift of the work function of GO was as high as 1.74 eV, after doping followed by thermal reduction.