Liquid Quantum Dots Research Articles

Thermal and optical investigations of self-loop system based on liquid quantum dots for laser lighting

This study proposes a self-loop converter (SLC) based on liquid quantum dots (QDs) that is designed for laser lighting. QDs exhibit unique illumination and display advantages because of their high light conversion efficiency and color purity. However, the unavoidable heat generated during light conversion leads to thermal quenching and limits their application in high-power laser lighting. The proposed SLC reduces the temperature and temperature fluctuations in the excited heating and gas circulation areas. After excited by laser for 240 min, the radiation power only decreases from 529.65 mW to 464.13 mW, a decrease of 12.37%. But the radiation power of hermitic converter (HC) decreased from 520.52 mW to 361.35 mW, decreasing by 30.5% after excited by laser for the same time. The experimental results demonstrate that the proposed SLC is promising for laser headlights, aerospace, coal mining, and other fields.

Novel Fenton process of Co-catalyst Co9S8 quantum dots for highly efficient removal of organic pollutants

Advanced oxidation processes (AOPs) have been widely accepted as an efficient and promising strategy for treating organic pollutants, is mainly dominated by hydroxyl radicals (•OH); however, its further practical application has been hindered by its low decomposition rate of H2O2. Hence, for the first time, we propose an eco-friendly and facile synthesis methodology synthesize water-soluble Co9S8 quantum dots (QDs) derived from commercial cobalt disulfide (CoS2), which can serve as excellent co-catalysts to dramatically enhance the decomposition rate of H2O2. It is demonstrated that the conversion rate of H2O2 into •OH is ca. 80.02% promoted by Co9S8 QDs, whereas the conventional Fenton process is ca. 34.9%. The result shows that unsaturated edged S atoms on the surface of Co9S8 play a pivotal role in this enhancement, where the number of protons will react with sulfur atoms to form H2S and expose reductive metallic active sites to accelerate the Fe3+/Fe2+ conversion. In addition, to tackle the issue for difficult recovery of liquid quantum dots, the magnetic Co9S8 QDs/Fe3O4 nanoparticles are particularly synthesized, which show excellent performance for degradation of 20 mg/L Rhodamine B (RhB). Moreover, the TOC degradation rate can remain stable at 80% even after five cycles. It is expected that this work will provide a new pathway of thinking in the Fenton process and impulse the usage of liquid quantum dots in practical AOPs application.

Fabrication of a Tyrosine-Responsive Liquid Quantum Dots Based Biosensor through Host-Guest Chemistry.

Design and fabrication of smart liquid quantum dots (LQDs) with high biomolecule selectivity and specificity remains a challenge. Herein, a multifunctional calix[4]arene derivative (PCAD) was rationally designed and applied to fabricate a Tyr-responsive CdSe-LQD system through host-guest chemistry. Such a biosensor displays an outstanding fluorescence/macroscopic response for Tyr and reversible fluidic features due to the hydrogen interaction between the PCAD of CdSe-LQDs and Tyr. These excellent results highlighted CdSe-LQDs as a promising platform for biological molecule recognition and separation in the future.

An ammonia gas detection system using liquid quantum dot LEDs based differential optical absorption spectroscopy

Detection of ammonia (NH3) concentration plays an important role in monitoring and controlling air pollutants. However, the existing NH3 detection methods do not conform to current needs. A low-cost and easily-realized gas sensing system for NH3 detection is developed using two near-infrared (NIR) liquid quantum dot light emitting diodes (QD-LEDs), a single photoelectric detector and time-division multiplexing (TDM) technique. The liquid-type NIR QD-LEDs are fabricated by a combination of PbSe QD solution with blue GaN LEDs. A long path gas cell is designed and adopted for realizing and enhancing gas detection. Detailed measurements are carried out to study the performance of the sensor system. The results show that the detection limit of the system is 10ppm, and the corresponding measurement relative error of 4 h continuous monitoring is less than 2%. The proposed sensor has potential applications in various fields requiring NH3 detection such as in atmospheric quality assessment, industrial products processing, medical diagnosis, and so on.

Chiral Responsive Liquid Quantum Dots.

How to convert the weak chiral-interaction into the macroscopic properties of materials remains a huge challenge. Here, this study develops highly fluorescent, selectively chiral-responsive liquid quantum dots (liquid QDs) based on the hydrophobic interaction between the chiral chains and the oleic acid-stabilized QDs, which have been designated as (S)-1810-QDs. The fluorescence spectrum and liquidity of thermal control demonstrate the fluorescence properties and the fluidic behavior of (S)-1810-QDs in the solvent-free state. Especially, (S)-1810-QDs exhibit a highly chiral-selective response toward (1R, 2S)-2-amino-1,2-diphenyl ethanol. It is anticipated that this study will facilitate the construction of smart chiral fluidic sensors. More importantly, (S)-1810-QDs can become an attractive material for chiral separation.

Macroscopic Responsive Liquid Quantum Dots Constructed via Pillar[5]arene-Based Host-Guest Interactions.

Liquid quantum dots (QDs) have been used as a fluorescent films sensor. Constructing a macroscopic, responsive, liquid QD system for lysine (Lys) is a challenging task. To achieve a selective macroscopic response towards Lys, herein we present a new strategy for integrating host-guest chemistry into a liquid QD system. Water-soluble pillar[5]arene WP5 was designed and synthesized as a host. WP5 was introduced onto the surface of PEG1810-modified QDs by host-guest interactions to obtain liquid WP5-1810-QDs. The interaction between WP5 and Lys is stronger than that between WP5 and PEG-1810, causing WP5 to be released from the 1810-QDs surface in the presence of Lys, resulting in macroscopic fluorescence quenching. This smart material shows promise in amino acid sensing and separation.

Suspension Array of Ionic Liquid or Ionic Liquid-Quantum Dots Conjugates for the Discrimination of Proteins and Bacteria.

It is of great importance to develop novel and sensitive sensing materials for the detection of proteins and microorganisms to fulfill the demand of disease diagnosis. As the selectivity and sensitivity of sensing systems are highly dependent on the receptor, the fluorescent sensor array with imidazolium ionic liquids (ILs) and ionic liquid-quantum dots conjugates as semiselective receptors is developed for protein/bacteria differential sensing or discrimination. The IL sensing system formed by 1,3-dibutylimidazolium chloride (BBimCl), 1,3-diethylimidazolium bromine (EEimBr), 1,3-dibutylimidazolium bromine (BBimBr), 1,3-dihexylimidazolium bromine (HHimBr), and 1,3-dioctylimidazolium bromine (OOimBr) and the IL@QDs/QDs sensing system formed by CdTe, BBimCl@CdTe, EEimBr@CdTe, BBimBr@CdTe, and HHimBr@CdTe are tested, by transferring the interaction binding difference between receptors and proteins to the fluorescent response pattern. The IL sensing system is applied to the identification of 48 samples (8 proteins at 500 nM) with an accuracy of 91.7%. For the IL@QDs/QDs sensing system, 8 proteins are completely distinguished with 100% accuracy at a very low concentration level of 10 nM. Remarkably, 36 training cases (6 strains of bacteria from 3 different species) are discriminated with 100% (OD600 of 0.1).

Liquid Quantum Dots Constructed by Host-Guest Interaction.

It is a challenging task to construct nonionic liquid quantum dots (QDs) with highly optical perfermance. To address the problem, we make a new strategy to construct liquid QDs via host-guest interaction between β-cyclodextrin and adamantane. Macroscopic fluidity and optical performance of liquid QDs can be controlled by the length of polyethylene glycol. The supramolecular compounds can make use of its excellent inclusion capacities to fasten flexible organic long-chain compounds on the surface of QDs to become nonionic. Compared with the ionic liquid QDs, nonionic liquid QDs based on supramolecular self-assembly offered a strong, fast host-guest interaction, avoiding multistep reactions that would be more favorable for maintaining the fluorescent property of QDs.

Correlation functions for the detection of Wigner molecules in a one-channel Luttinger liquid quantum dot

In one-channel, finite-size Luttinger one-dimensional quantum dots, both Friedel oscillations and Wigner correlations induce oscillations in the electron density with the same wavelength, pinned at the same position. Therefore, observing such a property does not provide any hint about the formation of a Wigner molecule when electrons interact strongly and other tools must be employed to assess the formation of such correlated states. We compare here the behavior of three different correlation functions and demonstrate that the integrated two point correlation function, which represents the probability density of finding two particles at a given distance, is the only faithful estimator for the formation of a correlated Wigner molecule.

Correlated sequential tunneling in Tomonaga–Luttinger liquid quantum dots

AbstractWe investigate tunneling through a quantum dot formed by two strong impurites in a spinless Tomonaga–Luttinger liquid. Upon employing a Markovian master equation approach, we compute the linear conductance due to sequential tunneling processes. Besides the previously used lowest‐order Golden Rule rates describing uncorrelated sequential tunneling (UST) processes, we systematically include higher‐order correlated sequential tunneling (CST) diagrams within the standard Weisskopf–Wigner approximation. We provide estimates for the parameter regions where CST effects are shown to dominate over UST. Focusing mainly on the temperature dependence of the conductance maximum, we discuss the relation of our results to previous theoretical and experimental results. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)