Rational Sulfur Vacancy Design Enhances the Electrochemical and Nonlinear Optical Properties of V₂CT_x/WS₂

The concurrent optimization of electrochemical energy storage and third-order nonlinear optical (NLO) performance within a single material system remains a fundamental challenge. Here, V₂CT_x/WS₂ composites were fabricated via a solvothermal method on carbon cloth substrates, and (V₂CT_x/WS₂)_x/PMMA were prepared for optical measurements. Interfacial interactions between V₂CT_x surface functional groups and WS₂ promote the formation of sulfur vacancies and interfacial charge redistribution during compositing. The enlarged interlayer spacing, three-dimensional WS₂ nanoflower architecture, and defect-rich structure collectively increase accessible active sites and facilitate charge transport. The V₂CT_x/WS₂ electrode delivers a specific capacity of 2251.95 F·g^-1 at 1 A·g^-1, retaining 94.80% of its initial capacity after 10 000 cycles. The assembled supercapacitor achieves an energy density of 47.93 Wh·kg^-1 at a power density of 983.45 W·kg^-1. For NLO performance, the (V₂CT_x/WS₂)₈/PMMA sample exhibits a nonlinear absorption coefficient β of 232 cm·GW^-1, a nonlinear refraction coefficient γ of -9.29 × 10^-4 cm²·GW^-1, and an optical limiting threshold of 1.09 J·cm^-2. The results demonstrate that V₂CT_x/WS₂ exhibits excellent electrochemical and NLO properties through composite structure design and defect engineering.