Effect of Noble Metal on CuO/SnO₂ Heterostructures Thin Films for H₂S Gas

Hydrogen sulfide (H2S) is recognized as a toxic gas, renowned for its capacity to inflict significant harm upon the respiratory and nervous systems. Consequently, the development of high-performance H2S sensors holds significant importance. However, traditional fabrication methods such as brush painting and drop casting often yield sensors with inconsistent batch responses due to the unpredictable film formation process, hindering their mass industrial production. Here, we have devised a novel approach to fabricate highly sensitive and selective H2S sensors utilizing Pd-anchored CuO/SnO2 heterostructures thin films. An investigation was conducted to analyze the impact of different noble metals (Pt, Au, Ag, and Pd) on CuO/SnO2 heterostructure thin films concerning their response to H2S. These films were synthesized through RF sputtering and subsequently decorated with varying durations of CuO (15, 30, 45, 60, and 75 s) and Pd nanoparticles (Nps) (3, 6, 9, and 12 s) using a sputtering process. Notably, a sputtering time of 60 s for CuO and 9 s for Pd significantly enhanced the H2S sensing performance and selectivity over other gases. The Pd-anchored CuO/SnO2 thin films revealed an exceptional result of 75.45% to 100 ppm H2S, demonstrating a detection capability down to 0.5 ppm. These noteworthy outcomes were attained under optimal operating conditions at a temperature of 150 °C. This innovative fabrication technique holds promise for the advancement of gas sensor technology, enabling the creation of portable sensor prototypes suitable for real-time sensing applications.