Zinc tin oxide/polyvinyl alcohol nanocomposites enable sensitive pH-dependent arsenic detection by quartz crystal microbalance

This study presents the synthesis, comprehensive characterization, and application of zinc tin oxide/polyvinyl alcohol (ZTO/PVA) nanocomposites as sensitive platforms for arsenic detection using quartz crystal microbalance (QCM) sensors. ZTO nanoparticles were synthesized via an optimized hydrothermal method and incorporated into PVA matrices at 5, 8, and 10 wt%. Structural and optical properties were investigated using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and UV-Vis spectroscopy. XRD confirmed the formation of cubic-phase ZTO with a preferred (311) orientation, while Raman analysis verified the retention of the inverse spinel structure. SEM images revealed increased surface roughness and nanoparticle agglomeration with rising ZTO-NPs content. Optical measurements showed bandgap tunability, with the main bandgap decreasing from 5.28 eV (pure PVA) to 3.81 eV (10% ZTO/PVA), indicating strong electronic interaction between the polymer matrix and nanofiller. The presence of dual-bandgap features suggests concurrent polymer- and filler-dominated transitions. QCM sensors modified with ZTO/PVA exhibited high sensitivity toward arsenic ions in aqueous media, with optimal performance at pH 3, showing a sensitivity of 70.64 Hz/ppm and a response time of ~ 10 s. A non-linear, concentration-dependent response was observed, with enhanced sensitivity at higher arsenic concentrations, reaching 113 Hz/ppm at 10 ppm. These findings underscore the potential of ZTO/PVA nanocomposites as effective, real-time sensing materials for environmental monitoring of arsenic contamination in water systems.