Improving the sensitivity and detection speed of methane gas at room temperature using a nanosensor based on lead sulfide (PbS) colloidal quantum dots

In this study, lead sulfide colloidal quantum dots (PbS CQDs) were used to fabricate a methane-sensitive nanosensor. First, a silver microelectrode was patterned on a glass substrate via lithography. The PbS CQDs were then synthesized through a chemical method and deposited onto the doped microelectrodes, forming the methane-detection sensor. The morphology and crystal structure of the PbS CQDs were characterized using field-emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray analysis (EDX) and X-ray diffraction (XRD). Sensor performance in methane gas was evaluated at room temperature, and the underlying mechanism for enhanced sensing, along with the influence of temperature, was analyzed. The synthesized nanoparticles had an average particle size of approximately 15 nm. The prototype demonstrated a linear detection range for methane from 5000 to 70,000 ppm, with response and recovery times of 15 s and 300 s, respectively, and a maximum sensitivity of 53.53 % at 70,000 ppm.