Synthesis And Characterization Of Nitrogen-Doped 3d Graphene Foam Prepared By Inductively-Coupled Plasma-Assisted Chemical Vapor Deposition

In this work, we developed a new CVD process for the direct synthesis of N-doped graphene based on thermal CVD with inductively-coupled plasma (ICP) assistance using pure nitrogen (N-2) gas source. 3D N-doped graphene foam (GP foam) was fabricated by CVD with ICP on Ni foam using acetylene (C2H2) carbon source and hydrogen (H-2) gas carrier at 700-1000 degrees C. The effects of various synthesis parameters including N-2/C2H2/H-2 gas flow ratio, ICP power, pressure, temperature and time on N-doped graphene structure have been systematically studied. Ni foam template was then etched in 3M HCl for an hour before subsequent characterizations by Raman spectroscopy, Xray photoemission spectroscopy (XPS) and scanning/transmission electron microscopy (SEM/TEM). An optimal condition for high-quality N-doped graphene foam structure was found to be N-2/C2H2/H-2 of 7/4/84, ICP power of 200 W, pressure of 0.7 Tor, temperature of 900 degrees C and time of 1 minute. Rama spectra exhibited dominant 2D and G peaks with low D peak and notable D' peak at 1624 cm(-1), indicating successful N-doping of few-layer graphene structure. The presence of N atoms and N-doping concentration in graphene was confirmed by XPS. SEM/TEM data confirm that the structures are nanometer-thick N-doped 3D graphene structure with good crystallinity. Therefore, the CVD with ICP process is a new promising method for direct synthesis of N-doped graphene due to advantages including the use of non-toxic nitrogen source, high crystallinity of produced N-doped graphene structure and well controlled N-doping process.