Super‐capacitive carbon materials with large micropores and rich mesopores synthesized using N, S co‐doped carbon dots as self‐templates

Abstract The self‐template approach to porous carbon utilizes the precursor's inherent skeletal structure to form pores. When the initial pore sizes in precursors are very small, the final pore sizes of the resulting porous carbon decrease further, because the pores usually collapse during high‐temperature calcination. In the case of carbon dots (CDs) as nanosized self‐templates, the pores primarily arise from the splintering of CDs, and the resulting pore sizes are usually less than 1 nm. To enlarge the pore sizes and produce more mesopores, nitrogen‐sulfur co‐doped carbon dots (NSCDs) are designed that utilize the synergistic pore‐forming effect of amide bonds and sulfur‐containing functional groups. Amide bonds can be broken by alkaline soaking to produce pores, while sulfur groups can decompose into gas during calcination to enlarge pores. After CDs self‐assembly, alkaline treatment and calcination, a series of hierarchical porous carbon materials are synthesized with a pore size distribution concentrated in the 1.1–1.6 nm range and an impressive mesopore volume ratio up to 47.2%. The symmetric supercapacitors assembled by such porous carbon exhibit the optimal energy density of 17.3 Wh kg −1 at a high‐power density of 7000 W kg −1 . This study provides a method to tune the pore sizes of carbon electrodes using CDs as self‐templates, so as to meet the requirement of supercapacitors working under different conditions.