Effect of heat treatment on the electrical conductivity of carbon–nitrogen onion nanomaterial based on the interpolyelectrolyte complex lignosulfonate–chitosan

The effects of the second step pyrolysis temperature on surface, structure, texture properties, and electrical conductivity of carbon onion nanomaterials based on the interpolyelectrolyte complex lignosulfonate–chitosan were studied. The results indicate that higher temperature of heat treatment leads to improvement of the porous structure and allows to obtain a carbon material with high value of specific electrical conductivity. The second step of heat treatment makes it possible to more fully remove oxygen- and hydrogen-containing functional groups from the carbon–nitrogen nanomaterial and increase the number of carbon–carbon double bonds, while a significant amount of built-in nitrogen is retained in the onion structure, which contributes to a significant decrease in electrical resistance. After the second step of the heat treatment, the specific electrical conductivity of the samples increased by 5–10 orders in comparison with initial carbon sample obtained at 600 °C. Experimental values for electrical conductivity of carbon onion nanomaterials were (1.67–2.98)·10^–2 S cm⁻¹, (0.27–0.38)·10^–2 S cm⁻¹ and 1.2–2.2 S cm⁻¹ for materials obtained at 900, 1100 and 1300 °C, respectively. Carbon nanomaterials are promising for practical use as electrically conductive dispersed particles in semiconductor technology.