Ni-Loaded SnO2-MoS2 Heterostructure for Highly Selective and Low-Temperature SO2 Sensing With Real-Time Device Integration.

Sulfur dioxide (SO2) is a critical pollutant associated with severe respiratory and cardiovascular effects, necessitating continuous monitoring in industrial and environmental settings. Existing analytical systems are accurate but bulky, expensive, and unsuitable for portable real-time operation. Current metal-oxide and 2D material-based sensors still face challenges including limited selectivity, high operating temperatures, and slow sensing kinetics. This work aims to develop a highly selective SO2 sensor using nickel-loaded SnO2-MoS2 hybrid nanostructures integrated on interdigitated electrode platforms. Pristine MoS2 nanoflowers were synthesized, hybridized with SnO2, and loaded with controlled Ni concentrations to enhance electronic modulation and surface adsorption. The fabricated films were characterized using FESEM, EDS, Raman, XRD, and UV-Vis and tested under dynamic gas exposure with real-time resistance acquisition. The 4N-SM-4 sample (4:1 SnO2: MoS2 with 4% Ni) demonstrated the best sensing behavior, achieving a response of 1609% at 20 ppm with a response time of 38 s, recovery time of 18 s, and a selectivity coefficient of 7. The limit of detection and quantification were 0.144 and 0.604 ppm, respectively. Excellent stability was observed across varying humidity and during 40-day continuous evaluation. The portable IDE-based readout system enables practical real-time deployment.