Three-dimensional hierarchical nitrogen-doped arch and hollow nanocarbons: morphological influences on supercapacitor applications

Abstract

We report nitrogen (N) doped nanocarbons with two different morphologies, arch and hollow structure, for supercapacitor (SC) application. A simple co-axial electrospinning approach and subsequent leaching and carbonization processes are employed to fabricate N-doped carbon nanostructures. The fabricated N-doped arch and hollow nanocarbons exhibit high N-contents of 9.02 and 8.73 wt%, high surface areas of 619 and 557 m² g⁻¹, and total pore volumes of 0.6589 and 0.5681 cm³ g⁻¹, respectively. The N-doped arch and hollow nanocarbons exhibit the maximum specific capacitances (C_sp) of 417 and 371 F g⁻¹ at 2 mV s⁻¹ in a three-electrode system and C_sp values of 230 and 212 F g⁻¹ at 2 mV s⁻¹ for a two-electrode system, respectively, in 1 M H₂SO₄ solution. The maximum energy densities of 8.4 and 7.5 W h kg⁻¹ are obtained for N-doped arch and hollow nanocarbons, respectively. Further, these novel carbon nanostructures also deliver good cycle stabilities of 98% for 5000 cycles at a current density of 1 A g⁻¹. Such outstanding SC electro-sorption ability is due to the high micro-texture and high N-content characteristics of carbon nanostructures.