Green β-Cyclodextrin Exfoliated Molybdenum Sulphide Based Multifunctional Poly(vinylidene fluoride) Nanogenerators Towards Piezocatalytic Water Remediation

Abstract

Developing multifunctional materials that support both energy harvesting and environmental remediation is vital for the advancement of sustainable technologies. In this study, we present a green, scalable approach for exfoliating molybdenum disulfide (MoS2) using β-cyclodextrin (β-CD) as an environmentally friendly intercalating and stabilizing agent. The resulting β-CD-exfoliated MoS2 (MCD) nanofillers exhibit excellent dispersion, reduced layer thickness, and strong interfacial compatibility with a poly(vinylidene fluoride) (PVDF) matrix. Incorporation of MCD into PVDF (PMCD nanocomposites), prepared via melt-mixing and solution casting, significantly promotes the nucleation of electroactive β- and γ-phases, as confirmed by FTIR, Raman spectroscopy, and WAXD, achieving a high polar phase content of ~ 94%. To further elucidate the microstructural evolution, 2D Raman mapping was employed, which revealed spatial distribution of α, β, and γ-phases within the PVDF spherulites in the nanocomposites. The Raman analysis demonstrated that the nanofillers act as heterogeneous nucleation centres, leading to oriented growth of electroactive PVDF chains and reduced spherulite size. The optimized PMCD (1:6) nanocomposite exhibits an enhanced piezoelectric coefficient (d33 ~ 88 pm/V) and dielectric constant (~ 34 at 0.1 Hz). A flexible nanogenerator fabricated from this film delivers an output voltage of ~ 72 V under mechanical excitation. Furthermore, the device shows excellent piezocatalytic degradation performance against Rhodamine B, Diclofenac, Ciprofloxacin, and Cr(VI), with degradation efficiencies reaching ~ 69.2%, ~ 71.4%, ~ 62.5%, and ~ 53.5%, respectively, under ultrasonic agitation. The enhanced catalytic activity is attributed to efficient charge separation and reactive species generation via the piezoelectric effect. This work offers a sustainable materials design strategy by combining green-exfoliated 2D nanofillers with electroactive polymers, enabling the development of next-generation flexible nanogenerators and multifunctional environmental devices.