Rational Construction of Cobalt Sulfide Nanoparticles Embedded in Hollow N, P, S Codoped Carbon Shells for Enhanced Supercapacitor Performance

An exquisitely designed nanostructure and hybridizing with heteroatom-doped carbon can significantly improve the electrochemical performance of the transition metal sulfides (TMSs). Herein, three-dimensional (3D) hollow N, P, S codoped carbon (NPSC) shells encapsulated with uniformly dispersed cobalt sulfide nanoparticles (Co1–xS/HNPSCS) are synthesized for supercapacitors (SCs) by the sulfuration and carbonization of poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS)-functionalized cobalt-based zeolitic imidazolate framework-67 (ZIF-67). The PZS protects the ZIF-67 from collapsing and convert it in situ into NPSC shells, which are conducive to exposing abundant active sites and accelerating the kinetics of electrochemical reactions. As a result, the Co1–xS/HNPSCS presents an unrivaled specific capacity of 1058.9 C g–1 at 1 A g–1. The assembled Co1–xS/HNPSCS//AC hybrid SC (HSC) demonstrates a remarkable energy density of 57.8 W h kg–1 at a power density of 375 W kg–1. Density functional theory calculations show that the synergy between the Co1–xS and NPSC can optimize the electronic configuration, improve the conductivity, and enhance the adsorption of OH– on the surface of the electrode material. Besides, the quantum capacitance of the carbon layer is also increased by N, P, S codoping. This work exhibits an effective strategy to fabricate TMS/HNPSCS and offers theoretical and methodological guidance for the study of NPSC coating materials.