Effects of underlayer on the reduction of graphene oxide through atomic hydrogen annealing and soft X-ray irradiation

The reduction of graphene oxide (GO) through atomic hydrogen annealing (AHA) and soft X-ray irradiation is investigated using microwell substrates with mu m-sized holes with and without Ni underlayers. The GO film is reduced through AHA at 170 degrees C and soft X-ray irradiation at 150 degrees C. In contrast, some GO films are not only reduced but also amorphized through soft X-ray irradiation. The effect of the Ni underlayer on GO reduction differs between AHA and soft X-ray irradiation. In AHA, the difference in GO reduction between SiO2 and Ni underlayer originates from the atomic hydrogen density on the sample surface. On the other hand, in soft X-ray irradiation, the difference in GO reduction between SiO2 and the Ni underlayer originates from the excited electrons generated by soft X-ray irradiation. Reduction without damage is more likely to occur in the suspended GO than in the supported GO.