Porosity and composition of nitrogen-doped carbon materials templated by the thermolysis products of calcium tartrate and their performance in electrochemical capacitors

Abstract

Porous nitrogen-doped carbon materials were synthesized by chemical vapor deposition method using template nanoparticles produced by the decomposition of calcium tartrate in thermal shock conditions. The synthesis temperature was varied from 650° to 900°C with a step of 50 °C and acetonitrile vapor was supplied into reactor immediately after the template formation. Transmission electron microscopy and X-ray diffraction analysis detected an increase of the number of ordered graphitic layers with the rise of the synthesis temperature. That was accompanied by a decrease of the specific surface area and the total pore volume determined from N2 adsorption measurements. Higher surface area of the materials produced at 650 and 700 °C was assigned to the co-existence of CaCO3 and CaO template nanoparticles at these temperatures. X-ray photoelectron spectroscopy found about 4–5 at% of nitrogen in all materials and a strong temperature-dependence of the ratio of nitrogen forms. The material synthesized at 750 °C showed the best electrochemical performance in 1 M H2SO4 electrolyte due to the presence of large fraction of pyridinic nitrogen responsible for pseudo-capacitance, graphitic nitrogen promoting charge transport, and large-size mesopores providing the fast diffusion of electrolyte ions.