Probing solid state N-doping in graphene by X-ray absorption near-edge structure spectroscopy

The evolution of solid state N-doping in graphene has been probed using X-ray absorption near-edge structure (XANES) spectroscopy. The XANES spectra show that the modification of graphene with N species can be achieved by urea attachment at annealing temperatures lower than 300 °C. A transition from urea to amino species is observed at 400 °C. At higher temperatures, pyridinic and graphitic type doping are achieved. The results indicate that the electronic structure of graphene can be controlled by solid state treatment, involving different N species depending on the annealing process.