Fiber-optic VOCs sensor utilizing a tunable nanostructured PVA/TOCNF composite aerogel coating

This study reports a high-performance fiber-optic volatile organic compound sensor based on a tunable nanostructured polyvinyl alcohol/TEMPO-oxidized cellulose nanofiber (PVA/TOCNF) composite aerogel coating, where TEMPO denotes 2,2,6,6-tetramethylpiperidine-1-oxyl. By precisely modulating the mass ratio of PVA to TOCNF, the influence mechanism of the nanoskeleton's morphological evolution on the gas-sensing performance was elucidated. A three-dimensional porous sensitive film with a high specific surface area and abundant functional groups was constructed in situ on the interference region of an SMF-MMF-SMF structure using dip-coating combined with freeze-drying technology. The results demonstrate that the sensor achieves optimal performance at a PVA/TOCNF mass ratio of 3:1, with an acetone sensitivity as high as 4.74 pm/ppm, a 22.15-fold increase compared to the pure PVA-coated sensor, alongside significantly enhanced selectivity and response speed. Furthermore, the sensor exhibits excellent repeatability and long-term stability. This work validates, for the first time, the feasibility of PVA/TOCNF composite aerogels in the field of optical gas sensing, providing a novel strategy for the development of eco-friendly, high-performance, and cost-effective fiber-optic VOC sensors.