Sensitive detection of sulfide based on the self-assembly of fluorescent silver nanoclusters on the surface of silica nanospheres

Hydrogen sulfide is a toxic and flammable gaseous pollutant often emitted to air as a by-product of water supply, chemical, petroleum and coal industries. It can be transferred into sulfur dioxide in the air under some meteorologic conditions. Herein, we report a novel ratiometric fluorescence method for hydrogen sulfide based on silver nanoclusters and quantum dots. The silver nanoclusters have been self-assemblied onto the surface of silica spheres, which are embedded with red fluorescent quantum dots, to form a dual-emissive nanohybrid. Such dual-emissive nanohybrid has been applied for hydrogen sulfide detection on the basis of the interfacial interaction between silver nanoclusters and sulfide ions. The blue-emission of Ag NCs is specifically prone to hydrogen sulfide due to surface binding and etching, but the red-emission of QDs within the silica nanospheres is inert against hydrogen sulfide. The different response of the two components to hydrogen sulfide results in fluorescence color variation from violet to red when the blue fluorescence is gradually quenched. This nanohybrid has been successfully demonstrated for the application in sensitive and selective detection of hydrogen sulfide in aqueous solution and gaseous state.