Novel Au-modified Nano-SnS2: synthesis, structural analysis, and enhanced gas sensing properties

Abstract This study reports a facile synthesis of Au-modified Nano-SnS2 composites through a combined water-thermal and in situ chemical reduction method, aimed at advancing low-temperature gas sensing technology. Comprehensive structural analyses using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy confirmed that incorporation of Au nanoparticles significantly alters the nanostructure. The results reveal that optimal Au loading at 0.5 wt% refines the crystallite size from approximately 25 nm to 20–23 nm, while uniformly distributed Au particles with diameters of 3–5 nm effectively form Schottky junctions that enhance interfacial charge transfer. Gas sensing measurements demonstrate that the sensor response increases from 4.7 at 1 ppm to 22.6 at 10 ppm NO2, and a linear correlation (R2 = 0.998) was observed in the lower concentration range of 1–4 ppm. Furthermore, the optimal operating temperature decreased from 140°C for the unmodified sensor to 120°C, contributing to reduced power consumption. The transient response characteristics also improved markedly, with a response time of 42 s and a recovery time of 127 s, in contrast to 220 s and 520 s for the pristine material. Long-term stability tests over 40 days revealed less than 4% variation in sensor performance, and selectivity experiments confirmed a strong preference for NO2 over other interfering gases. Overall, the synergistic effects of Au-induced electronic sensitization and catalytic activity result in enhanced sensitivity, faster kinetics, and excellent durability. These significant findings offer valuable insights for designing highly efficient sensors for environmental monitoring, paving the way for future sensor technology.