Well-Defined N/S Co-Doped Nanocarbons from Sulfurized PAN-<i>b</i>-PBA Block Copolymers: Structure and Supercapacitor Performance

Abstract

While nanocarbons doped with more than one heteroatom continue attracting growing interest owing to a wide range of applications, precise control of their nanostructure and porosity remains a major challenge. Herein, we report a new route to synthesize N/S co-doped nanocarbons with precise porosity control through introduction of sulfur into the synthesis copolymer-templated nitrogen-enriched carbons (CTNC). Sulfur served as both a heteroatom source and morphology stabilizing agent. The produced N/S co-doped nanocarbons showed interconnected pores with relatively high specific surface area (∼480 m2/g) and high heteroatom content (N, 8.2 atom %; S, 8.8 atom %). To demonstrate the dual benefits of sulfur stabilization (incorporation of heteroatoms and improved morphology control), such prepared nanocarbons were fabricated into supercapacitors with geometric capacitance (50 μF/cm2), well above the value observed for single N-doped carbon (33 μF/cm2). Importantly, linear relationship of mesopore size with block length of copolymer precursor was observed for N/S co-doped nanocarbons, allowing optimization of the mesopore size for supercapacitor applications. This new technique not only expands CTNC method from N-doping to N/S co-doping systems with excellent porosity control but also opens up new possibilities widely applicable to other PAN-based soft-templating systems.