This work investigates some electrical properties of carbon material based on pyrogallol and formaldehyde matrix enriched by zirconium oxide nanoparticles (PFZr) synthesised by the sol–gel method, followed by high-temperature heat treatment in an inert atmosphere. Zirconium oxide nanoparticles (ZrO2) can be readily synthesised using cost-effective methods such as the sol–gel technique. As a crystalline oxide, ZrO2 exhibits remarkable thermal stability and is widely regarded as a promising high-k dielectric material for advanced complementary metal–oxide–semiconductor (CMOS) technologies. Incorporating ZrO2 nanoparticles into a carbon matrix significantly enhances the final properties of the polymer composite, including an increased surface area and an improved ability to degrade organic impurities, thanks to the unique characteristics of the ZrO2 nanopowder. Focusing on samples pyrolysed at 600 °C, we observed non-linear I–V characteristics, with a notable S-type NDR phase. Our analysis suggests that this phenomenon is attributed to the Joule heating effect. Furthermore, we examine the correlation between voltage and current thresholds and measurement temperature. These results are promising avenues for developing negatronic devices and the practical implementation of on-demand negative differential resistance behaviour in nanostructure-based materials through precise temperature control.