Precursor-controlled and template-free synthesis of nitrogen-doped carbon nanoparticles for supercapacitors

Abstract

We describe the synthesis of hierarchical porous nitrogen-doped carbon nanoparticles with high specific surface area and specific capacitance for supercapacitors. Octapyrrolylnaphthalene (OPN) with eight substituent pyrrolyl groups is used as a reaction precursor and the oxidative product, assigned as POPN, is synthesized in miniemulsion droplets. Further carbonization of POPN at 600 °C (POPN600) and 800 °C (POPN800) provides particles with hierarchical porosity, well-defined nanoparticle structure, and high specific surface area. The obtained nitrogen-doped carbon particles POPN800 exhibit a specific capacitance of 156 F g⁻¹ at the scan rate of 2 mV s⁻¹ and 80 F g⁻¹ when the scan rate increases to 100 mV s⁻¹. The high specific capacitance and excellent rate capability can be attributed to the controlled structure of the nanoparticles, hierarchical micro- and mesoporosity, high surface area (365 m² g⁻¹), and rich nitrogen-doping. The present method allows therefore for the synthesis of nitrogen-doped carbon materials for supercapacitors in an easy one-pot and template-free miniemulsion procedure followed by carbonization.