رزگار احمدی

Doping is an important method to modulate the electronic properties of graphene. Among various types of doped graphene, sulfur-doped graphene is expected to have a wider band gap due to the electron-withdrawing character of sulfur. However, it is difficult to dope graphene with sulfur because sulfur atom is much larger than C atom. In this study, we developed a low temperature, economical and facile onepot hydrothermal method to synthesis S-doped reduced graphene oxide (S-RGO) nanosheets. The percentage doped atoms in graphene is an effective factor in improving the properties of its electrochemical. Here, we changed some of parameters and increased value of doped sulfur in graphene sheets which associated with electrocatalytic properties in the oxygen reduction reaction (ORR). The as-prepared S-RGO has advantages such as a high S content, highquality sulfurated species (mainly as C–S–C–), numerous open edge sites and defecting on its surface which are beneficial for the improved ORR catalytic activity. Electrochemical characterizations of the synthesized nanocatalyst S-RGO clearly demonstrated the excellent electrical conductivity and superior electrocatalytic activity for oxygen reduction reaction (onset: - 0.11 V), compared to the commercial Pt/C catalyst.