摘要： Fluorescent quantum dots of carbon and semiconductor have superior optical properties and show great potential in sensing applications. This paper reports a novel method for rapid detection of uranyl ions via ratiometric fluorescence signals by employing the two types of quantum dots as the key materials. As the most soluble and stable toxic uranium species, uranyl has been recognized as an important index for nuclear industrial wastewater. However, its on-site, rapid and sensitive determination remains challenging. This work uses the ratiometric fluorescent signal of quantum dots and combines a smartphone-based handheld device for on-site and rapid detection of uranyl. The ratiometric fluorescent probe is achieved by integrating carbon dots (C-dots) and CdTe quantum dots (MPA@CdTe QDs) through chemical hybridization. The presence of uranyl ions greatly quenches the red ?uorescence of the CdTe QDs, whereas the green ?uorescence keeps constant, leading to obvious color change. An App and a 3D-printed accessory have been developed on a smartphone to analyze and calculate the content of uranyl on the basis of captured fluorescence signals from a test strip with immobilized probe. This new designed mobile detection system displays good analytical performance for urnayl ions in wide concentration range from 1 μM to 150 μM, which shows great potential application in controlling the nuclear industrial pollution.