A synergistic 1T-VS2/NiTe2@NbCl5 heterostructure for high-performance supercapattery and electrocatalytic applications.

Supercapattery devices integrate high-energy-density batteries with fast-rate power supercapacitors (SCs). 2D metal chalcogenides are tailored electrode materials due to their inherent metallic conductivity and rich redox-active sites. In this work, we synthesized an NbCl5-doped 1T-VS2/NiTe2 heterostructure via a hydrothermal process to yield a well-defined hierarchical architecture with tunable crystallinity and enhanced surface morphology. Comprehensive structural and textural characterization using XRD, SEM, and BET verified the successful fabrication of the heterostructure. In electrochemical tests, the composite electrode delivered a specific capacity (Qs) of 1500 C g-1 at 2.0 A g-1 to demonstrate unambiguous redox charge retention. The as-fabricated supercapattery device (1T-VS2/NiTe2@NbCl5//AC) exhibited a Qs value of 170 C g-1 at 2.0 A g-1. The device also revealed a specific energy densit (Ed) of 86.2 Wh kg-1 at a specific power density (Pd) of 700 W kg-1, with 79.2% capacity retention (CR) after 10 000 loops. The coulombic efficiency (CE) was sustained at ≈85.9% throughout prolonged cycling to confirm structural robustness under repeated electrochemical stress. Furthermore, the composite exhibited an excellent oxygen evolution reaction (OER) response, with a low Tafel slope of 55.65 mV dec-1 under alkaline conditions (1 M KOH). This is attributed to synergistic interfacial coupling and NbCl5-induced interfacial electronic interaction. These findings reveal the potential of NbCl5-doped 1T-VS2/NiTe2 as an electrode-active species for multifunctional energy retention and electrocatalysis.