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

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.