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

Abstract

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, W N, of 3–23 mass% and the specific surface area by N 2 adsorption, S BET, of 60–2000 m 2 g −1 without activation. Generally high nitrogen content of the starting compound led to larger W N, but W N was not proportional to the N/C mole ratio in the compounds. The value of S BET strongly depended on the compound: S BET (PVP) > S BET (PAA) ≫ S BET (TMM). There was a tendency for W N to decrease with increasing S BET. The capacitance measured in 1 mol dm −3 H 2SO 4 by cyclic voltammetry, C M in F g −1, suggested that both W N and S BET are influential in gaining large C M. For the composites with W N > 5 mass%, the capacitance normalized by S BET, C A = C M/ S BET, 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 C M. The value of C A increased with increasing W N, but a correlation between C A and particular nitrogen species on the surface measured by XPS was obscure. It was suggested that the large C A 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.