Ultrasensitive and selective room temperature H2S detection using Pd-doped MoS2 synthesized via APCVD

The detection of trace amounts of hazardous hydrogen sulfide (H₂S) gas is crucial for environmental monitoring and industrial safety. In this study, pristine and palladium (Pd)-doped molybdenum disulfide (MoS₂) thin films with varying Pd concentrations (1, 2, 5, and 10 at%) were synthesized on SiO₂/Si substrates using atmospheric pressure chemical vapor deposition (APCVD). Gas sensing performance was analyzed at room temperature (RT) in a dynamic flow gas sensing setup. The 5 at% Pd-doped MoS₂ sensor exhibited the best response of 276 % at 100 ppm H₂S, significantly outperforming pristine MoS₂, which showed a response of 96 %. The sensor also exhibited rapid response and recovery times of 45 and 65.8 s, respectively. A limit of detection (LoD) of 0.3 ppb and a limit of quantification (LoQ) of 0.99 ppb were achieved, indicating ultrasensitive detection capabilities. Additionally, density functional theory (DFT) studies were conducted to provide theoretical validation of the experimental results, to confirm that the Pd doping changes the electronic properties of MoS₂ and enhances its interaction with H₂S gas molecules. Comprehensive characterization techniques, including X-ray diffraction (XRD), Raman spectroscopy, I-V characteristics, and X-ray photoelectron spectroscopy (XPS) confirmed the successful synthesis and doping of MoS₂ with Pd. This combined experimental and computational study provides valuable insights into the effects of Pd doping on MoS₂ resulting in the superior gas sensing performance of the 5 at% Pd-doped MoS₂ through the present investigations. As grown 5 at% Pd-doped MoS₂ sensor was characterized by excellent reproducibility, long-term stability and selectivity, making it a promising candidate for real- time, highly sensitive H₂S detection at trace levels