Highly sensitive and selective carbon dot sensor for hydrogen sulfide based on dual quenching effect

Due to the serious impact of hydrogen sulfide (H₂S) on the environment and human health, a series of sensors have been increasingly used in industrial production and daily life. In this work, we introduce a novel, to the best of our knowledge, detection method for trace H₂S in the liquid and gaseous phases based on the dual-quenching mechanism (DQE) of silver ion-doped nitrogen-sulfur co-doped carbon dots (N, S-CDs@Ag⁺). Ag⁺ could significantly enhance the fluorescence intensity and detection sensitivity. In the linear detection range of 10-120 nM H₂S solution, the N, S-CDs@Ag⁺ sensor has a limit of detection (LoD) of 0.83 nM and a response time of 1 min. An enhanced fluorescent sensing film is prepared by assembling N, S-CDs@Ag⁺ on a silica microsphere (SM) microstructured substrate (N, S-CDs@Ag⁺/SM@PVA) using the layer-by-layer method. In the linear detection range of 1-50 ppm, the film sensor has the advantages of low detection limit (0.41 ppm), fast response time (5 min), stable performance, electromagnetic interference resistance, ease of integration, and in-field detection. It is expected to develop into a compact portable on-site H₂S trace sensor.