Sacrificial Template Synthesis of Two-Dimensional Few-Layer MoSe₂Coupled with Nitrogen-Doped Carbon Sheets for High-Performance Sodium Ion Hybrid Capacitors

Molybdenum diselenide (MoSe2) is emerging as a promising anode material for sodium-ion hybrid capacitors (SIHCs) due to its high theoretical capacity. However, the limited rate capability and the poor stability restrain its practical applications. Herein, we report a template approach to prepare two-dimensional (2D) few-layer MoSe2 embedded in nitrogen-doped carbon sheets (MoSe2@NCS). Specifically, graphitic carbon nitride is in situ transformed as the sacrificial template, which not only inhibits the accumulation of the MoSe2 but also endows the MoSe2@NCS composite with a 2D morphology. Benefiting from this architecture, the heterostructure reveals the accelerated ion diffusion rate, enhanced electronic conductivity, and well-controlled volume expansion. Consequently, the MoSe2@NCS delivers a high specific capacity of 398.9 mAh g-1 at 0.1 A g-1 and a good rate performance of 229 mAh g-1 at 5 A g-1. Meanwhile, an outstanding long cyclic stability with high capacity of 225.2 mAh g-1 is maintained after 1000 cycles at 1 A g-1. Hence, a SIHC based on the MoSe2@NCS anode is established and exhibits a high energy of 122.8 Wh kg-1 at 105 W kg-1 and power densities of 65.3 Wh kg-1 at 10500 W kg-1.