Synthesis of Three-Dimensional Nitrogen and Sulfur Dual-Doped Graphene Aerogels as an Efficient Metal-Free Electrocatalyst for the Oxygen Reduction Reaction

摘要

Three-dimensional (3D) nitrogen and sulfur dual-doped graphene aerogels (NSGAs) are successfully synthesized by using a rational hydrothermal self-assembly process with ammonia and sulfur powder as nitrogen and sulfur sources, respectively. Structural characterization, including TEM, HAADF-STEM, SEM, and XPS indicated that the NSGA catalyst exhibits an interconnected macroporous framework of graphene sheets and tunable contents of N and S. The as-prepared NSGAs show an excellent electrocatalytic activity for the oxygen reduction reaction, including a highly positive onset potential, high kinetic limiting current density, and fuel tolerance. In particular, the NSGA catalyst reveals a much better long-term stability than that of Pt/C in alkaline medium.