An electrical solid-state sulphur dioxide vapour sensor based on a polyvinyl alcohol formaldehyde composite

Abstract

Polyvinyl alcohol formaldehyde (PVF)-based composites are synthesized and applied for rapid detection and quantification of sulphur dioxide (SO₂) vapours by electrical impedance measurements. A series of polymeric composites, namely PVF/single-walled carbon nanotubes (PVFCNTs), PVF/carbon nanoparticles (PVFCNPs), PVF–coumarin-6 (PVFCOU), PVF/thiophene (PVFTH) and PVF/cytochrome-6-oxidase (PVFCY), are synthesized in high yields by a simple one-pot approach. These were characterized by FT-IR, AC conductivity and FESEM. The composites were then used for the impedimetric detection of SO₂ vapours, and the sensitivity was found to follow the order: PVFCOU > PVFTH > PVF. The current vs. voltage (I–V) curves further demonstrated a second-order decrease in conduction for PVFCOU upon exposure to SO₂ vapours. Amongst the synthesized composites, PVFCOU exhibited an excellent response time of 3 s for 400 ppt SO₂, with a limit of detection of 1.15 ppb. Our findings demonstrate, for the first time, an AC electrical impedance-based SO₂ detection, using the PVFCOU polymeric composite. In addition, this polymeric composite fulfills the dual function of highly efficient sensing and analyte sequestration. Thus, PVFCOU may be an ideal cost-effective solid-state sensor material for onsite vapour sensing applications.