Preparation of freestanding and flexible vanadium dioxide membranes with multifunctional applications

Abstract

Freestanding vanadium dioxide (f-VO₂) membranes with reversible metal–insulator transition (MIT) are emerging as promising candidates for intelligent functional devices. However, achieving f-VO₂ membranes in an efficient and cost-effective manner remains a significant challenge. Herein, we present a facile and low-cost method combining vacuum filtration and post-thermal treatment to fabricate f-VO₂ membranes, in which H₂V₃O₈ nanowires with a large aspect ratio are employed as the precursor, and polyethyleneimine (PEI) is introduced as a reducing agent. The resulting f-VO₂ membranes are composed of a continuous VO₂ nanowire network, and the resistance change ratio is close to 4 orders of magnitude during the MIT process. The flexibility of f-VO₂ can be further improved by introducing polydimethylsiloxane (PDMS). In the X-band, the f-VO₂/PDMS composite membrane demonstrates exceptional switchable electromagnetic interference (EMI) shielding performance, with ΔSE reaching ∼30 dB. Additionally, the photoresponse behavior, information encryption design, and infrared modulation properties of the f-VO₂ membranes are also explored. These findings highlight the multifunctionality of the f-VO₂ membrane, which holds great potential for broader applications.