VOx/Au/PVA nanocomposites synthesized through plasma liquid chemistry: Simultaneous vanadium valence control and in Situ Au formation

Vanadium oxides (VO x ) are emerging as multifunctional materials due to their tunable oxidation states and diverse structural phases. In parallel, gold nanoparticles (AuNPs) exhibit unique plasmonic and photothermal properties. Here, we demonstrate a novel one‑pot plasma-induced liquid chemistry (PiLC) route to directly fabricate multifunctional VO x /AuNP/poly(vinyl alcohol) (PVA) nanocomposites under ambient conditions. Uniquely, the PiLC process enables (i) the simultaneous phase transformation of V 2 O 5 into mixed-valence VO 2 /V 2 O 3 and (ii) the in situ nucleation of AuNPs, without external reducing agents, surfactants or thermal treatment. Structural characterization confirms successful VO x phase transformation, the formation of AuNPs and their uniform dispersion within the PVA matrix. The resulting nanocomposites exhibit temperature-dependent optical transmission modulation, coupled with highly efficient photothermal conversion under 808 nm near-infrared irradiation. Importantly, this photothermal response translates directly into rapid antibacterial activity against both E. coli and S. aureus. This work establishes PiLC as a single-step, eco-friendly platform for the concurrent synthesis, phase engineering and functional integration of metal oxides and plasmonic nanoparticles in polymers, opening new opportunities for smart coatings, antimicrobial interfaces and NIR-responsive systems.