Supercapacitor electrode with high charge density based on boron-doped porous carbon derived from covalent organic frameworks

We developed a facile and unique process for preparing boron-doped porous carbon by direct carbonization of a boron-based covalent organic framework (COF-5). Boron oxides, which are formed during the carbonization of COF-5, were readily removed through water treatment of the resulting carbon to obtain boron-doped porous carbon. Thus, boron atoms were successfully incorporated into the carbon matrix. Supercapacitor electrodes made of the fabricated boron-doped carbon exhibited a specific capacitance of 15.3 μF cm⁻² at 40 mA g⁻¹, which is twice that of the conventional activated carbon electrode (∼6.9 μF cm⁻²) at the same current density, owing to the presence of boron atoms in the carbon material. The supercapacitors based on boron-doped carbon demonstrated 72% capacitance retention after 10000 charge/discharge cycles. The boron-doped COF-derived carbon materials can serve as a new class of multifunctional carbon materials for energy storage devices.