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

Dual-Emission of Lanthanide Metal–Organic Frameworks Encapsulating Carbon-Based Dots for Ratiometric Detection of Water in Organic Solvents

Nitrogen and sulfur codoped carbon-based dots (N,S-CDs) with strong blue light emission are encapsulated into red light-emitting europium metal–organic frameworks (Eu-MOFs) to form two color light-emitting nanohybrids (Eu-MOFs/N,S-CDs). In organic solvents, the encapsulated N,S-CDs are aggregated and confined in the cavities of the Eu-MOFs, exhibiting only a very weak photoluminescence (PL) signal. Therefore, the nanohybrids show red light emission of the Eu-MOFs. Contrarily, when the Eu-MOFs/N,S-CDs are dispersed in water, the encapsulated N,S-CDs are released into solution while the red light emission of the Eu-MOFs is quenched due to the effect of O–H oscillators. The nanohybrids are used as the probe for the water content in organic solvents. Take ethanol as an example; as the water content is increased from 0.2 to 30%, the nanoprobe provides distinguishable PL color change. The ratio of light intensity at 420 nm to that at 623 nm (<i>I</i>₄₂₀/<i>I</i>₆₂₃) increases linearly with increasing water content in the range from 0.05 to 4% with a low detection limit of 0.03%

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

Graphene Quantum Dots/l‑Cysteine Coreactant Electrochemiluminescence System and Its Application in Sensing Lead(II) Ions

A new coreactant electrochemiluminescence (ECL) system including single-layer graphene quantum dots (GQDs) and l-cysteine (l-Cys) was found to be able to produce strong cathodic ECL signal. The ECL signal of GQD/l-Cys coreactant system was revealed to be mainly dependent on some key factors, including the oxidation of l-Cys, the presence of dissolved oxygen and the reduction of GQDs. Then, a possible ECL mechanism was proposed for the coreactant ECL system. Furthermore, the ECL signal of the GQD/l-Cys system was observed to be quenched by lead­(II) ions (Pb²⁺). After optimization of some important experimental conditions, including concentrations of GQDs and l-Cys, potential scan rate, response time, and pH value, an ECL sensor was developed for the detection of Pb²⁺. The new methodology can offer a rapid, reliable, and selective detection of Pb²⁺ with a detection limit of 70 nM and a dynamic range from 100 nM to 10 μM

Polyphenylbenzene as a Platform for Deep-Blue OLEDs: Aggregation Enhanced Emission and High External Quantum Efficiency of 3.98%

Great efforts have been devoted to seek novel approaches for the construction of efficient deep-blue fluorescent materials, one of the most important prerequisites for the commercialization of OLEDs. Here, we report a new way to utilize polyphenylbenzene as a platform to yield a series of efficient deep-blue emitters. Nondoped multilayer electroluminescence (EL) devices using these new luminogens as emitting layers are fabricated. Maximum current efficiency (CE) of 2.0 cd A^–1 is achieved and the Commission Internationale de l’Éclairage (CIE) coordinates can stay at (0.15, 0.08), close to the saturated deep-blue (0.14, 0.08). Through rational design of the device structure, blue-violet emission with the CIE coordinates of (0.15, 0.06) can be realized. Furthermore, <b>10</b>-based doped devices show deep-blue emission with improved CE as high as 4.51 cd A^–1, and the external quantum efficiency (EQE) of 3.98%, which are among the best EL performance for deep-blue emission