Dual-interface engineering: Sulfur-doped Co3O4 nanoparticles confined hollow porous carbon spheres for enhanced hybrid supercapacitors

초록

Developing electrode materials with high energy density and long-term durability remains a critical challenge for supercapacitor technology. Here, we report sulfur-doped Co3O4 nanoparticle-decorated porous carbon hollow spheres synthesized via a controlled hydrothermal–carbonization–etching process. The dual-interface core–shell architecture anchors Co3O4 nanoparticles on both inner and outer surfaces of hollow carbon shells, creating plentiful electroactive sites and multidirectional transport paths. Sulfur doping modifies the electronic structure, improves electrical conductivity, and strengthens Co–S interfacial bonding, thereby accelerating redox kinetics and refining structural stability. The optimized hybrid system delivers a specific capacitance of 576 F g−1 at a current density of 0.5 A g−1, with a capacitance retention of 91.5% after 10,000 cycles. The assembled hybrid supercapacitor device achieves an energy density of 79.3 Wh kg−1 at a power density of 1050 W kg−1, outperforming most reported Co3O4–carbon core–shell systems. Density functional theory calculations show that sulfur doping narrows the bandgap and enhances electronic coupling at Co–S interfaces, which facilitates fast charge transfer. Furthermore, first-principles calculations predict that the dominant contribution of S–doped Co3O4 electronic states near the Fermi level significantly enhances electrical conductivity, thereby improving the intrinsic supercapacitive performance. This work reports a scalable approach for engineering heteroatom doped metal oxide–carbon core–shell hybrids for high-performance supercapacitors. © 2026 Elsevier Ltd.

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