Carbon Quantum Dot-Functionalized Aerogels for NO₂ Gas Sensing

Silica aerogels functionalized with strongly fluorescent carbon quantum dots were first prepared and used for simple, sensitive, and selective sensing of NO₂ gas. In the presence of ethanol, homemade silica aerogels with a large specific surface area of 801.17 m²/g were functionalized with branched polyethylenimine-capped quantum dots (BPEI-CQDs) with fluorescence quantum yield higher than 40%. The prepared porous CQD-aerogel hybrid material could maintain its excellent fluorescence (FL) activity in its solid state. The FL of CQD-aerogel hybrid material could be selectively and sensitively quenched by NO₂ gas, suggesting a promising application of the new FL-functionalized aerogels in gas sensing

Polyamine-Functionalized Carbon Quantum Dots as Fluorescent Probes for Selective and Sensitive Detection of Copper Ions

A novel sensing system has been designed for Cu²⁺ ion detection based on the quenched fluorescence (FL) signal of branched poly­(ethylenimine) (BPEI)-functionalized carbon quantum dots (CQDs). Cu²⁺ ions can be captured by the amino groups of the BPEI-CQDs to form an absorbent complex at the surface of CQDs, resulting in a strong quenching of the CQDs’ FL via an inner filter effect. Herein, we have demonstrated that this facile methodology can offer a rapid, reliable, and selective detection of Cu²⁺ with a detection limit as low as 6 nM and a dynamic range from 10 to 1100 nM. Furthermore, the detection results for Cu²⁺ ions in a river water sample obtained by this sensing system agreed well with that by inductively couple plasma mass spectrometry, suggesting the potential application of this sensing system