PdS nanoparticles inlaid in lettuce-like structure SnS2 for high-selectivity and ppt-level-sensitivity NO2 sensing at room temperature

Two-dimensional tin sulfide (SnS 2 ) shows great promise as a NO 2 gas-sensing material due to its large specific surface area and suitable band structure, yet its selectivity and detection limit remain inadequate. Herein, PdS/SnS 2 composite with PdS nanoparticle inlaid in lettuce-like structure SnS 2 was synthesized via a facile microwave-assisted method for room-temperature NO 2 detection. The optimized PdS/SnS 2 composite exhibits that the response value to 5 ppm NO 2 reached 2560% at room temperature under 50% relative humidity, which is approximately 10.7 times that of pristine SnS 2 (238%). Importantly, its experimental limit of detection (LOD) for NO 2 is as low as 800 ppt, while the theoretical LOD is below 164 ppt. Furthermore, it also shows outstanding reversibility and repeatability (RSD < 5%), and high selectivity (response ratio > 40) against interfering gases. The enhanced sensing performance is attributed to the synergistic effect of the PdS/SnS 2 heterojunction and sulfur vacancies, which promotes NO 2 gas adsorption on the material surface and electron transport inside the material. This study provides a feasible strategy for designing high-precision and ultra-trace NO 2 sensors with ppt-level detection capabilities at room temperature.