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Size dependence of photocatalytic hydrogen generation for CdTe quantum dots
摘要： CdTe quantum dots (QDs) are attractive photosensitizers for photocatalytic proton reduction due to their broad absorbance profile that can extend from the ultraviolet to near-infrared regions, providing access to a larger portion of the solar spectrum than possible with analogous CdSe and CdS QD photosensitizers. Here, the photocatalytic hydrogen (H2) generation from various sizes of dihydrolipoic acid (DHLA)-capped CdTe QDs, ranging from 2.5 to 7.5 nm in diameter, and a molecular Ni-DHLA catalyst in aqueous solutions was evaluated, and an unusual size-dependent photocatalytic activity with CdTe QDs was observed. Under optimized conditions, using 3.4 nm CdTe-DHLA and a 1:20 ratio of QD/Ni-DHLA catalyst, as many as 38 000 turnover numbers (mol H2 per mol QD) were achieved. However, below this critical size, the H2 production efficiency decreased; this behavior is attributed to the rapid oxidation of the QD surface, resulting in detrimental surface trap states. These results are consistent with ultrafast transient absorption spectroscopic measurements, which suggest the presence of extremely fast charge-trapping processes in the oxidized CdTe-DHLA QDs. While fast electron transfer from CdTe-DHLA QDs is observed in the presence of the Ni-DHLA catalyst, the charge trapping processes occur on a competitive time scale, thus lowering the efficiency of the CdTe/Ni-DHLA H2 production system. Understanding rapid charge trapping in CdTe QDs may help suggest potential improvements for the overall CdTe photocatalytic system.
关键词： size dependence,photocatalytic hydrogen generation,Ni-DHLA catalyst,CdTe quantum dots,dihydrolipoic acid
更新于2025-09-12 10:27:22
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Synthesis, Characterization,and Photocatalytic activity of Silver nanoparticledoped Phosphomolybdic acid supportedZirconia
摘要： An ecofriendly solid acid catalyst was synthesized by impregnating phosphomolybdic acid on zirconia followed by doping with Silver nanoparticles to form composite. We report here, the synthesis, characterization and photocatalytic behavior of AgNPs doped Keggin Ions/ Zirconia which is synthesized by wet impregnation method. The resulting nanocomposite was characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-Visible spectroscopy. The photocatalytic activity of the catalyst was evaluated for the degradation of azo dye under the Visible light irradiation. In the photoreaction study, it is found that photocatalytic activity increases by doping the noble metal silver nanoparticles on PMA/ZrO2 surface to form the composite.
关键词： Phosphomolybdic acid,Zirconia,Methylene blue dye,Photocatalytic activity
更新于2025-09-12 10:27:22
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Fullerene derivative layer induced phase separation and charge transport improvement for inverted polymer solar cells
摘要： The phase separation of donor and acceptor in bulk-heterojunction plays an important role on the exciton dissociation and charge carrier transport, which decides the performance of organic solar cells (OSCs). In this paper, the thin [6,6]-Phenyl-C71-butyric acid methyl ester (PC71BM) layer was incorporated as interlayer between active layer and the polyethylenemine electron transport layer of OSCs to realize high efficiency. Both a high short-circuit current density and fill factor were achieved, resulting in a power conversion efficiency up to 9.17% for the optimal device. The incorporation of PC71BM layer not only induced vertical phase separation of active layer to improve exciton dissociation and charge transfer but also modified surface morphology to increase light absorption of the active layer. This study offers a simple and lost cost strategy to improve performance of OSCs.
关键词： Light absorption,Electron transport,[6,6]-Phenyl-C71-butyric acid methyl ester,Exciton dissociation,Phase separation
更新于2025-09-12 10:27:22
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CdTe Quantum Dots Modified with Cysteamine: A New Efficient Nanosensor for the Determination of Folic Acid
摘要： In this paper, we report the synthesis, characterization, and application of a new fluorescent nanosensor based on water-soluble CdTe quantum dots (QDs) coated with cysteamine (CA) for the determination of folic acid (FA). CdTe/CA QDs were characterized by high-resolution transmission electron microscopy, the zeta potential, and Fourier-transform infrared (FT-IR), UV-visible, and fluorescence spectroscopy. CdTe QDs coated with mercaptopropionic acid (MPA) and glutathione (GSH) were prepared for comparison purposes. The effect of FA on the photoluminescence intensity of the three thiol-capped QDs at pH 8 was studied. Only CdTe/CA QDs showed a notable fluorescence quenching in the presence of FA. Then, a nanosensor based on the fluorescence quenching of the CdTe QDs at pH 8 was explored. Under optimum conditions, the calibration curve showed a linear fluorescence quenching response in a concentration range of FA from 0.16 to 16.4 μM (R2 = 0.9944), with a detection limit of 0.048 μM. A probable mechanism of fluorescence quenching was proposed. The nanosensor showed good selectivity over other possible interferences. This method has been applied for FA quantification in orange beverage samples with excellent results (recoveries from 98.3 to 103.9%). The good selectivity, sensitivity, low cost, and rapidity make CdTe /CA QDs a suitable nanosensor for FA determination.
关键词： electron transfer,folic acid nanosensor,positive quantum dots,fluorescence quenching
更新于2025-09-12 10:27:22
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Bright Cool White Emission from Ultrasmall CdSe Quantum Dots
摘要： In this work we employ a post-synthesis ligand treatment of ultrasmall CdSe quantum dots (QDs) with citric acid to increase the quantum yield (QY) of the of the as-synthesized CdSe from an average of 5.7% to a maximum of 61.3%. This is the highest reported value for a single component white-light emitting QD. The white-light emission of the ultrasmall CdSe quantum dots is derived from three surface states: pinned emission at a trap state associated with the phosphonic acid surface ligand, a surface Se state, and conventional deep trap states. The citric acid treated CdSe QDs were found to recover band gap emission from the phosphonic acid ligand trap state emission, exhibiting behavior . This band gap emission peak also becomes more prominent, resulting in a cooler white, as indicated by the shift in the CIE coordinates from an average of (0.30, 0.36) to (0.26, 0.32). Comparing to a previous method of increasing the QY by a post-synthesis treatment of formic acid, the citric acid treated CdSe QDs are brighter as well as more stable in solution over time, which opens the possibility for use in multiple applications.
关键词： white-light emission,quantum yield,quantum dots,citric acid,CdSe
更新于2025-09-12 10:27:22
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Fabrication of pH-responsive TA-keratin bio-composited hydrogels encapsulated with photoluminescent GO quantum dots for improved bacterial inhibition and healing efficacy in wound care management: In vivo wound evaluations
摘要： Wounds origins serious complications of lives of human beings which may leads to death. The important issue for the problem is infection during wound care management which delays wound healing process. These kinds of infections may be caused by the overuse or misuse of antibiotics, antidotes, usage of new drugs, not properly sterilized surgical instruments, not appropriate for pH level and imperfect wound dressing etc. during or after surgery. Hence in this report, antimicrobial action of pH responsive TA/KA composited hydrogel crosslinked with GO-QDs (TA/KA-GOQDs) using citric acid as cross- linker has been reported by demonstrating in-vitro and in-vivo studies for wound care management. The prepared samples of GOQDs, TA/KA hydrogel and TA/KA-GOQDs were characterized using FT-IR, XRD, SEM and TEM techniques. pH responsive hydrogel property of TA/KA was evaluated by swelling studies. In-vitro antibacterial studies was carried out by direct contact test method. Further, the prepared samples were tested in a wound healing model of rate with the wound of size 1.5 cm2 for in-vivo studies. After 16 days of treatment, the prepared samples for wound healing causes 100% wound areas closure. Histological observations were made by MT and HE staining process which proves keratinocytes proliferation by biocompatible and biocomposited TA/KA-GOQDs. The pH responsive TA/KA-GOQDs proved as efficient wound healing agent by faster keratinocytes proliferation within a compact period.
关键词： pH responsive hydrogel,Tannic acid,Graphene oxide,Wound Care Management
更新于2025-09-12 10:27:22
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A colorimetric sensor array for recognition of 32 Chinese traditional cereal vinegars based on “turn-off/on” fluorescence of acid-sensitive quantum dots
摘要： Colorimetric sensor array is a sensitive, rapid, and inexpensive detection technology which simulates human olfaction system based on various organic dyes. In this work, a sensor array based on acid-sensitive CdTe QDs coupled with chemometrics method was developed and proved to be a rapid, accurate and sensitive method for identification of 32 kinds of Chinese traditional cereal vinegars (CTCV). The specificity of identification of this method was mainly depends on the organic acids and melanoidins of CTCV. Among them, organic acids can quench the fluorescence of QDs through enhancing their electron transfer (hydrogen bond) and resonance energy transfer, and the fluorescence intensity of melanoidin was closely related to the brewing technology and aging year of CTCV. The types and aging time of 32 CTCV can be 100% identified at a dilution of 1000 by partial least squares discriminant analysis, when the latent variables were 4. And only one kind of QDs is needed instead of various organic dyes to this kind of colorimetric sensor array. Except for vinegar, this method can also be used in the identification of other food which rich in organic acid.
关键词： Chemometrics,Chinese traditional cereal vinegars,Fluorescence sensors,CdTe quantum dots,Organic acid
更新于2025-09-12 10:27:22
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Blue LED light irradiation enhances L-ascorbic acid content while reducing reactive oxygen species accumulation in Chinese cabbage seedlings
摘要： Chinese cabbage is one of the most representative vegetables in Southeast Asia and a main source of L-Ascorbic acid (AsA) for the human diet. In this study, we applied di?erent light qualities (red, blue and white) supported by light-emitting diode (LED) device to enhance AsA content in Chinese cabbage (Brassica rapa ssp. pekinensis) seedlings. Based on our results, blue LED light irradiation with an intensity of 125 μmol m?2s?1 increased the AsA content of ?ve-day-grown Chinese cabbage seedlings by 40% compared with white LED light irradiation. Accordingly, blue LED light irradiation induced expression of the AsA biosynthetic- and recycling-related genes. Interestingly, the reactive oxygen species (ROS) content of Chinese cabbage seedlings was decreased by blue LED light irradiation. In addition, the technology improving AsA content by blue LED light irradiation was applicable to other edible vegetable sprouts as well as to Chinese cabbage sprouts. Conclusively, our report introduces a source technology for arti?cially improving the AsA content of Chinese cabbage seedlings by applying blue LED light, which implies that application of certain types of LED light enables on-purpose cultivation of crops.
关键词： Chinese cabbage,Blue light,Ascorbic acid (AsA),Light-emitting diode (LED),Antioxidant
更新于2025-09-12 10:27:22
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Photo-Switchable Boronic Acid Derived Salicylidenehydrazone Enabled by Photochromic Spirooxazine and Fulgide Moieties: Multiple Responses of Optical Absorption, Fluorescence Emission, and Quadratic Nonlinear Optics
摘要： A novel protocol of the boronic acid derived salicylidenehydrazone (BASHY) core being sandwiched by photochromic spirooxazine and fulgide moieties was proposed here to design multistate fluorescent photoswitches with variable nonlinear optical (NLO) responses. Systematic investigations on their optical absorption, fluorescence emission, and static first hyperpolarizabilities (β) were performed using density functional theory (DFT). It was found that the BASHY-based sandwiched series exhibited significant differences of absorption and emission properties between three photoisomers, which were essentially ascribed to the massive changes of corresponding electron transition characteristics quantified by hole–electron descriptors and visualized by electron density difference (EDD) plots. However, the isomerization of fulgide parts in the merocyanine (MC) form of spirooxazine failed to greatly shift maximum absorption/emission wavelengths, due to their high similarity of intrinsic transition features. Furthermore, large β contrasts between three photoisomers were observed, which resulted from significant variations of contributions of spirooxazine and/or fulgide moieties to the total β upon photoisomerization according to β densities. Although the fulgide moiety contributes negatively and positively to spirooxazine (SO) isomers when fulgide switches from close (C-) to open (E-) forms, respectively, their dominant βxxx values with opposite signs are still similar in magnitude, leading to quite close quadratic NLO responses. Therefore, the captivating ternary photoswitches with multiple responses of absorption, emission, and NLO were elaborately built in this context, promising to be applied as multifunctional optical materials in various scientific and technological fields.
关键词： photochromic spirooxazine,fulgide moieties,nonlinear optical (NLO) responses,density functional theory (DFT),boronic acid derived salicylidenehydrazone (BASHY)
更新于2025-09-12 10:27:22
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Enhanced Electrochemiluminescence of Porphyrin-based Metal-Organic Frameworks Controlled via Coordination Modulation
摘要： Precise control over composition, morphology and size of porphyrin-based metal-organic frameworks is challenging but the extension of these hybrid materials will enable the creation of novel electrochemiluminescence (ECL) emitters. The coordination of various entities are made from Zn2+ ions and meso-tetra(4-carboxyphenyl)porphine (TCPP), modulated by both solvent and bathophenanthrolinedisulfonic acid disodium salt (BPS) as capping agent, resulting in limited crystal growth of Zn-TCPP in DMF/H2O (V/V, 1:1) and the formation of nanoscale TCPP-Zn-BPS. The role of BPS is also evaluated using Zn-TCPP and BPS-Zn-TCPP as control, prepared in the absence of BPS and different coordinating sequence of ligands, respectively. The newly obtained TCPP-Zn-BPS exhibits a variety of different morphologies, as well as, spectral, and optoelectronic properties. The ECL behavior of the TCPP-Zn-BPS is investigated by using H2O2 as co-reactant. The amplification of ECL is further studied by ECL spectroscopies and cyclic voltammetry, with the corresponding mechanism proposed.
关键词： bathophenanthrolinedisulfonic acid disodium salt (BPS),Electrochemiluminescence,meso-tetra(4-carboxyphenyl)porphine (TCPP),coordination modulation
更新于2025-09-12 10:27:22