MgO-templated nitrogen-containing carbons derived from different organic compounds for capacitor electrodes

Carbons containing nitrogen (C–N composites) were derived from three commercial organic compounds, poly(vinylpyrrolidone) (PVP), polyacrylamide (PAA), and trimethylolmelamine (TMM) using the MgO template method. The C–N composites formed in nitrogen at 700–1000 °C had nitrogen content, WN, of 3–23 mass% and the specific surface area by N2 adsorption, SBET, of 60–2000 m2 g−1 without activation. Generally high nitrogen content of the starting compound led to larger WN, but WN was not proportional to the N/C mole ratio in the compounds. The value of SBET strongly depended on the compound: SBET (PVP) > SBET (PAA) ≫ SBET (TMM). There was a tendency for WN to decrease with increasing SBET. The capacitance measured in 1 mol dm−3 H2SO4 by cyclic voltammetry, CM in F g−1, suggested that both WN and SBET are influential in gaining large CM. For the composites with WN > 5 mass%, the capacitance normalized by SBET, CA = CM/SBET, was 0.17–0.65 F m−2, which was larger than the electric double layer capacitance (0.05–0.15 F m−2), indicating that the pseudo-capacitance contributes significantly to CM. The value of CA increased with increasing WN, but a correlation between CA and particular nitrogen species on the surface measured by XPS was obscure. It was suggested that the large CA is not simply explained by redox reactions of the surface functional groups. The composite derived from PAA at 900 °C showed 234 F g−1 at 2 mV s−1 and 181 F g−1 at 100 mV s−1 with acceptable yield of the composite.