Nanoporous fluorescent sensor based on upconversion nanoparticles for the detection of dichloromethane with high sensitivity

A sensor with high sensitivity and response rate is still lacking in the detection of poisonous and volatile chemicals. Here, we report a highly sensitive nanoporous fluorescence sensor based on core@shell upconversion nanoparticles (UCNPs) for the detection of dichloromethane. UCNPs were deposited on porous anodic alumina oxide (AAO) templates supported by glass slides to form a thin film-like gas sensor in which UCNPs with active shells exhibit intense background-free fluorescence and simultaneously high optical sensitivity, while an AAO template acts as a porous substrate for UCNPs to increase the absorption capacity for molecules to be tested. A detection limit of 2.91 ppm was obtained for dichloromethane based on this sensor at room temperature. The involved response mechanism was attributed to lowered surface fluorescence quenching and scattering of UCNPs by dichloromethane.