Tailoring Pt-Loaded MoS2/SnO2 Heterostructures for High-Sensitivity Room-Temperature Ammonia Detection: A DFT and COMSOL Analysis

Abstract

Metal oxide semiconductor (MOS) nanostructures have been explored intensively for gas detection; however, they often need high operating temperatures, consume high power, and demonstrate poor selectivity. 2D transition metal dichalcogenides (TMDs) enable low-power gas detection at room temperature (RT) but typically lack sufficient selectivity and sensitivity. To address these limitations, TMD/MOS heterostructures have emerged as potential candidates for high-performance RT sensing. In this research, density functional theory (DFT) calculations have been employed to examine the gas adsorption properties of the MoS2/SnO2 heterostructure. The heterostructure exhibits a significant bandgap reduction of 0.512 eV upon NH3 adsorption, a high chemiresistive sensitivity of 2.13 × 10 6 %, and a fast recovery of 7 s. Furthermore, the sensor was modeled in COMSOL Multiphysics with platinum (Pt) loading on the MoS2/SnO2 heterostructure. Under optimized Pt loading, the Pt-MoS2/SnO2 sensor demonstrated an enhanced response of 93.85% to 100 ppm NH3 with a superior sensitivity (0.9255 ppm⁻ 1 ) at RT. Additionally, the Ptloaded MoS2/SnO2 heterostructure exhibited excellent selectivity toward NH3 in the presence of various interfering gases. A faster response/recovery of 11/8 s was obtained, demonstrating its promise for practical applications. Moreover, the impact of relative humidity (RH) on sensor performance has been analyzed. The outstanding sensing characteristics are attributed to the synergistic effects of the MoS2/SnO2 heterostructure and Pt loading, facilitating efficient electron transfer and reduced activation energy. These results provide significant information for designing selective, energy-efficient, next-generation gas sensors with the added benefit of predictive modeling prior to device fabrication.