Carboncones, a special family of all-carbon allotropes, are predicted to have unique properties that distinguish them from fullerenes, carbon nanotubes, and graphenes. Owing to the absence of methods to synthesize atomically well-defined carboncones, however, experimental insight into the nature of pure carboncones has been inaccessible. Herein, we describe a facile synthesis of an atomically well-defined carboncone[1,2] (C₇₀H₂₀) and its soluble penta-mesityl derivative. Identified by x-ray crystallography, the carbon skeleton is a carboncone with the largest possible apex angle. Much of the structural strain is overcome in the final step of converting the bowl-shaped precursor into the rigid carboncone under mild reaction conditions. This work provides a research opportunity for investigations of atomically precise single-layered carboncones having even higher cone walls and/or smaller apex angles.

Biomass-derived carbon materials have been widely researched due to their advantages such as low cost, environmental friendliness, readily available raw materials. Black fungus and Hericium erinaceus contain many kinds of amino acids. In this paper, unique O, N-codoped black fungus-derived activated carbons (FAC_X), and Hericium erinaceus-derived activated carbons (HAC_X) were prepared by KOH chemical activation under different temperatures without adding additional reagents containing nitrogen and oxygen functional groups, respectively. As electrode materials of symmetric supercapacitors, FAC₂ and HAC₂ calcined at 800 °C exhibited the highest specific capacitance of 209.3 F g⁻¹ and 238.6 F g⁻¹ at 1.0 A g⁻¹ in the two-electrode configuration with 6.0 M KOH as the electrolyte, respectively. The X-ray photoelectron spectroscopy confirmed that the as-synthesized FAC_X and HAC_X contained small amounts of nitrogen and oxygen elements. Moreover, heteroatom-doped FAC₂ and HAC₂ electrode materials shown excellent rate performance (84.1% and 75.0% capacitance retention at 20 A g⁻¹, respectively). By comparison, the oxygen-rich hierarchical porous carbon (HAC₂) shows higher specific capacitance and energy density and longer cycling performance. Nevertheless, carbon-rich hierarchical porous carbon (FAC₂) indicates excellent rate performance. Biomass-derived heteroatom self-doped porous carbons are expected to become ideal active materials for high performance supercapacitor.