Surface-plasmon-enhanced optical formaldehyde sensor based on CdSe@ZnS quantum dots

摘要： For the first time, a reproducible surface-plasmon-enhanced optical sensor for the detection of gaseous formaldehyde was proposed by depositing the mixture of CdSe@ZnS quantum dots (QDs), fumed silica (FS) and gold nanoparticles (GNs) on the surface of silica spheres array to meet the urgent requirement of a rapid, sensitive, and highly convenient formaldehyde detection method. Due to the spectra overlap between QDs and GNs, plasmon-enhanced fluorescence was observed in the film of QDs/FS/GNs. When exposing to formaldehyde molecules, the enhanced fluorescence was quenched linearly with the increase of formaldehyde concentration in the range of 0.5-2.0 ppm. The reason is attributed to the nonradiative electron transfer from QDs to the carbonyl of formaldehyde molecules with the assistance of amino groups. Our results demonstrate that the designed sensors are capable of detecting ultralow concentration gaseous formaldehyde at room temperature with a fast response-recovery time, excellent selectivity, stability and reproducibility. This work provides a simple and low-cost approach for optical formaldehyde sensor fabrication and shows promising applications in environmental detection.