Synthesis and Characterization of Nitrogen-Doped Graphene Nanowalls by Plasma-Enhanced Chemical Vapor Deposition for High Voltage Supercapacitors: Effects of Carbon Sources

Abstract

In this work, CH4, C2H4, and C2H2, were used as carbon sources and mixed with Ar and NH3 to prepare nitrogen-doped graphene nanowalls (N-GNWs) via the plasma-enhanced chemical vapor deposition method. When C2H4 and C2H2 were employed to synthesize GNWs without N doping, their adhesion on the Ti substrate was very poor; this was significantly improved by the introduction of NH3 into the reaction chamber to produce N-GNWs (denoted as N-GNW-C2H4 and N-GNW-C2H2). All N-GNWs vertically grown on the Ti substrates need the electrochemical activation step to promote their specific capacitance (CS). The as-prepared N-GNW-C2H2 showed the highest CS, about 35–40 F g−1, which can be promoted to be 76 F g−1 after electrochemical activation. All N-GNWs are confirmed to be suitable materials for the negative electrode of a high-voltage, asymmetric supercapacitor in organic electrolytes. X-ray diffraction, Raman spectroscopy, and secondary ion mass spectroscopy were utilized to examine the differences in microstructures of N-GNWs prepared from various carbon sources.