A Facile Synthesis of Nitrogen/Sulfur Co-Doped Graphene for the Oxygen Reduction Reaction

摘要

The design and fabrication of oxygen reduction reaction (ORR) electrocatalysts with high performance at low cost remains a big challenge but is crucial for the commercialization of fuel cells. Here, we report a simple and economical method for the direct mass production of nitrogen/sulfur co-doped graphene (NS-G) by using cysteine as single precursor and self-assembled NaCl as a structure-directing template through the solid-phase pyrolysis method. The resultant NS-G possesses a high specific surface area of 435.13 m(2)g(-1), effective N (1.85 at%) and S (0.99 at%) dual doping and enhanced conductivity, which contribute largely to the exposure of highly active sites and to the promotion of electron transport in the ORR process. Accordingly, the NS-G exhibits excellent ORR performance with a positive half-wave potential of 0.768 V (versus reversible hydrogen electrode), four-electron pathway, low Tafel slope of 60 mVdec(-1), and high stability in alkaline medium. These merits make NS-G a promising alternative to costly Pt for ORR.