Synthesis of multi-heteroatom green-doped bamboo-derived carbon materials using a simple one-step carbonization method: A micro/macro exploration of the effects of different heteroatoms on supercapacitors

While significant progress has been made in studying multi-heteroatom co-doped carbon materials, considerable challenges remain in thoroughly exploring how various heteroatoms impact their properties. This study synthesized multi-heteroatom co-doped bamboo-derived carbon materials using a simple one-step carbonization process combined with a green heteroatom doping strategy. The effect mechanism of heteroatom types and functional group types on their electrochemical properties was analyzed from micro- and macro-perspectives through experiments and simulations. The best carbon material (KHBS-2) provided excellent heteroatom content (N: 2.44 %, O: 10.19 % and S: 0.58 %). KHBS-2 displayed superior gravimetric capacitance (324.62 ± 5.70 F/g), volumetric capacitance (336.59 ± 9.02 F/cm3). Symmetric supercapacitors assembled with KHBS-2 achieved extraordinary cycling stability (99.07 %). At the microscopic scale, typical N-containing active sites (N-5, N-6 and N-Q) significantly enhanced the adsorption of K ions on porous carbon. Moreover, the adsorption of K ions by carbon materials can be significantly enhanced with the simultaneous presence of N-5, N-X and N-Q with C-O. And the C-S functional group could weaken the adsorption effect of N/O functional groups on K ions to a certain extent. On this basis, this study investigated the effects of different types of active sites on the density of states and electrostatic potential of carbon materials.