Ratiometric Optical Sensing of Hydrogen Sulfide at Room Temperature Using CsPbBr ₃ and InP/ZnSeS Quantum Dots for Environmental and Industrial Monitoring

This study presents a facile fabrication method for an optical sensing film designed for the detection of H 2 S at the ppb level, based on a ratiometric approach using CsPbBr 3 and E610-InP/ZnSeS quantum dots. The sensing film exhibited excellent linearity, with correlation coefficients ( R 2 ) of 0.9684 in the 100–500 ppb range and 0.9844 in the 1–10 ppm range, while maintaining high reproducibility with relative standard deviations (RSD) below 5.2%. Minimal interference was observed from O 2 (100%), CO 2 (100%), NO (100 ppm), NH 3 (300 ppm), and water vapor. Furthermore, the film demonstrated robust photostability under continuous LED illumination for 90 min. At a concentration of 10 ppm, the response time (↓ t 90 ) and recovery time (↑ t 90 ) were 95 and 490 s, respectively. Mechanistic investigations using XRD, Raman spectroscopy, temperature-dependent analysis, partial irreversibility assessment, and Stern–Volmer evaluation confirmed that photoluminescence quenching in CsPbBr 3 arises from both static and dynamic mechanisms, involving PbS formation and excited-state energy transfer, respectively. The integration of stable E610-InP/ZnSeS reference quantum dots enabled real-time signal normalization, ensuring reproducible and reliable H 2 S detection under varying environmental conditions. These results highlight the potential of the proposed ratiometric sensing film for H 2 S monitoring across a broad concentration range, suitable for environmental and industrial monitoring applications.