Nitrogen-Doped Carbon Cloth for Supercapacitors Prepared via a Hydrothermal Process

Abstract

This paper reports a facile means of fabricating nitrogen-doped carbon cloth (CC) via a hydrothermal process in the presence of hydrazine and ammonia. The resulting N-doped CC can be used directly as an electrode for a supercapacitor, requiring no polymeric binder or current collector. X-ray photoelectron spectroscopy (XPS) revealed that the surface of oxidized CC was nitrogen-doped concurrently with reduction; in other words, the oxygen-containing groups were replaced with nitrogen species of different types depending on the composition and temperature of the hydrothermal bath. The highest areal capacitance was estimated to be 136 mF cm−2 at a current density of 0.5 mA cm−2 for a N-doped CC electrode treated at 160°C, while the capacitance remained at 81% of its original value when the applied current density was increased from 0.5 to 15 mA cm−2. We explored the role of different nitrogen species in the capacitive process based on a combination of XPS and electrochemical measurements. High hydrothermal temperatures and the presence of NH3 yielded pyridinic nitrogen atoms, leading to fast electron transfer during charge/discharge cycles.