Nitrogen, phosphorus and sulfur tri-doped hollow carbon nanocapsules derived from core@shell zeolitic imidazolate framework@poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) for advanced supercapacitors

The rational design and facile synthesis of multiple heteroatoms co-doped hollow carbon nanomaterials with high electrochemical performance still remain a challenge. Herein, an effective and facile method is proposed for the fabrication of N, P and S tri-doped hollow carbon nanocapsules (NPS-HCN) via direct carbonization and subsequent acid etching of a rationally designed core@shell nanostructured precursor, which is prepared by coating crosslinked poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) onto the zeolitic imidazolate framework. Due to its distinctive hollow nanostructure feature, large specific surface area (865 m² g⁻¹), and high heteroatom content (6.01 at% for N, 0.68 at% for P, 1.95 at% for S), the NPS-HCN as supercapacitor electrode material delivers prominent performances with large specific capacitance (351 F g⁻¹ at 1 A g⁻¹), great rate capability (242 F g⁻¹ at 20 A g⁻¹) and long-term cycle stability (97.1% capacitance retention after 10,000 cycles). Remarkably, the constructed symmetric supercapacitor using NPS-HCN delivers a high voltage output of 2.0 V and an excellent energy density of 37.72 Wh kg⁻¹ at a power density of 499.97 W kg⁻¹. These results demonstrate that this study might offer an effective strategy to generate multiple heteroatoms co-doped hollow carbon nanomaterials for achieving advanced energy storage.