Highly Sensitive and Selective Sensing of H₂S Gas Using Precipitation and Impregnation-Made CuO/SnO₂ Thick Films

In this work, CuO-loaded tetragonal SnO₂ nanoparticles (CuO/SnO₂ NPs) were synthesized using precipitation/impregnation methods with varying Cu contents of 0-25 wt% and characterized for H₂S detection. The material phase, morphology, chemical composition, and specific surface area of NPs were evaluated using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller analysis. From gas-sensing data, the H₂S responses of SnO₂ NPs were greatly enhanced by CuO loading particularly at the optimal Cu content of 20 wt%. The 20 wt% CuO/SnO₂ sensor showed an excellent response of 1.36 × 10⁵ toward 10 ppm H₂S and high H₂S selectivity against H₂, SO₂, CH₄, and C₂H₂ at a low optimum working temperature of 200 °C. In addition, the sensor provided fast response and a low detection limit of less than 0.15 ppm. The CuO-SnO₂ sensor could therefore be a potential candidate for H₂S detection in environmental applications.