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Unprecedented surface stabilized InP quantum dots with bidentate ligands
摘要： For InP-based QDs, the current technology does not outperform CdSe-based QDs in many respects, one of which is stability. The optical stability of QDs is closely related to their surface properties, so QDs often use organic ligands for surface protection. These organic ligands are dynamically attached and detached on the QD surface; during detachment, their surfaces are easily damaged and oxidized, thereby deteriorating their optical characteristics. Therefore, we have synthesized a ligand 1,2-hexadecanedithiol with a bidentate form, inducing one ligand to bind to the QD surface strongly through the chelate effect, as a good way to improve the stability of the QDs; thus, the PL stability of the green-light-emitting InP-based QDs was greatly increased. To confirm the existence of the dithiol ligand, we used thermogravimetric analysis/simultaneous thermal analysis-mass spectroscopy (TGA/STA-MS). After that, we applied the ligand to blue-light-emitting ZnSe QDs and red-light-emitting InP QDs, and for those two types of QD we also confirmed that the stability was increased. Additionally, we tested dithiol exchanged QDs at a high temperature of 150 °C, and the increase of stability was effective even in a high temperature condition.
关键词： stability,quantum dots,bidentate ligands,InP-based QDs,TGA/STA-MS
更新于2025-09-23 15:19:57
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Insulator-Metal Transition in CaTiO<sub>3</sub> Quantum Dots induced by Ultrafast Laser Pulses
摘要： Based on time dependent density functional theory (TDDFT), we have studied the interaction between ultra-fast laser pulses and two kinds of calcium titanate quantum dots (PCTO-QDs and MCTO-QDs). Under the action of localized field effect, ultrafast lasers can induce quantum dots to make the transition from insulator to metal. PCTO-QDs are ultimately metallic, while MCTO-QDs are still insulator after experiencing metal state. This is bacause the stability of the unsaturated atoms in the outermost layer of PCTO-QDs is weak and the geometric configuration of MCTO-QDs as a potential well will also reduce the damage of laser. Moreover, laser waveforms approaching the intrinsic frequency of quantum dots tend to cause the highest electron levels to cross the Fermi surface. In this paper, it is reported that the insulating quantum dots can be transformed into metal by adjusting the intensity and frequency of laser. It emphasizes the importance of local morphology by comparing the difference about two kinds of CTO-QDs. More importantly, it is a step to identify the potential properties of perovskite materials.
关键词： CaTiO3 QDs,metallic transformation,ultra-fast laser
更新于2025-09-23 15:19:57
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A facile in situ growth of CdS quantum dots on covalent triazine-based frameworks for photocatalytic H2 production
摘要： CdS quantum dots (QDs) are excellent visible-light-driven photocatalysts due to their unique small size (<10 nm), suitable band energy structure, and short charge transportation length. Unfortunately, the easy aggregation of CdS QDs to form larger particles results in a higher recombination rate for photoinduced electron-hole pairs, which deteriorates the photocatalytic activity. Here, we report in situ growth of CdS QDs with high dispersion and stability on covalent triazine-based frameworks (CTFs) via a facile photoreduction method. The photocatalytic H2 evolution activity of CdS QD-loaded CTFs is effectively enhanced to approximately 55 and 4 times than that of pristine CTFs and bulk CdS, respectively. This enhanced photocatalytic performance is mainly ascribed to the higher separation rate of photogenerated carriers resulting from synergistic QD-on-sheet interactions between CdS QDs and CTFs. This work develops an efficient one-pot strategy to prepare metal-sulfide QDs with high dispersion and underlines the potential of utilizing CTFs as a suitable platform to develop efficient photocatalytic systems.
关键词： In situ growth,CdS QDs,Photocatalysis,Visible light,H2 evolution,Covalent triazine-based frameworks
更新于2025-09-23 15:19:57
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Efficient Perovskite Solar Cells Based on CdSe/ZnS Quantum Dots Electron Transporting Layer with Superior UV Stability
摘要： Stability is the main challenge in the field of perovskite solar cells (PSCs). Finding new strategies is required to protect the PSCs from deteriorated agents such as humidity, heating, and illumination. In this study, we propose a new electron transporting layer (ETL), i.e., CdSe/ZnS quantum dots (QDs) for the fabrication of efficient and stable PSCs. CdSe/ZnS QDs layer not only works as an ETL but also has down-shifting property, which can improve both efficiency and stability of the PSCs. Using CdSe/ZnS QDs ETL with green emission, a PSC with maximum power conversion efficiency (PCE) of 18% is achieved. More importantly, our device shows great UV stability much better than the device with TiO2 ETL, where it retains 90% of its initial PCE value after 75 h under continuous UV illumination.
关键词： down-shifting layer,perovskite,solar cell,CdSe/ZnS QDs,stability,UV stability
更新于2025-09-23 15:19:57
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Enhanced photocatalytic activity of Ag-CsPbBr3/CN composite for broad spectrum photocatalytic degradation of cephalosporin antibiotics 7-ACA
摘要： A visible-light-induced antibiotics degradation system based on a nano-Ag, CsPbBr3 quantum dot (QDs) and bulk g-C3N4 (CN) ternary assembly (Ag-CsPbBr3/CN) has been firstly constructed under an organic phase environment, oleylamine (OLA) and oleic acid (OA) were used as surfactants to stabilize the CsPbBr3, L-cysteine was used to facilitate the interaction between nano-Ag, CsPbBr3 and CN. The new ternary assembly of Ag-CsPbBr3/CN composite was used to degrade 7-aminocephalosporanic acid (7-ACA) under visible light irradiation, and the 7%-Ag-CsPbBr3/CN composite displayed the superior photocatalytic activity, approximately 92.79% of 7-ACA has been degraded to CO2, H2O and other small molecules at 140 min, which was approximately 1.49-folds, 1.56-folds, 3.01-folds and 11.43-folds higher than 9%-CsPbBr3/CN, 7%-Ag/CN, pure CN and pure CsPbBr3, respectively. A possible mechanism for 7-ACA degradation over Ag-CsPbBr3/CN composite were proposed according to detailed measurements of adsorption test, Brunauer-Emmett-Teller (BET) measurement, UV-vis diffuse reflectance spectra (DRS), photoluminescence spectra (PL), transient photocurrent response and electrochemical impedance spectroscopy (EIS) measurement, and the enhanced photocatalytic activity of Ag-CsPbBr3/CN composite could be attributed to the excellent adsorbability, the enhanced light-harvesting and reduced charge recombination, as well as the synergistic effects of nano-Ag and CsPbBr3 co-loaded with CN. In addition, Holes (h+) and hydroxyl radicals (·OH) played major roles, electronic (e-) and superoxide radical (·O2-) played minor roles based on the reactive-species-trapping experiments, the NBT transformation and the 7-hydroxycoumarin fluorescent experiments. Furthermore, a possible 7-ACA degradation pathway was investigated based on the Liquid Chromatography-Mass spectroscopy (LC-MS) experiment to better understand the degradation process. The present opens up a new insight for using CsPbBr3 as photocatalyst to degrade antibiotics.
关键词： CsPbBr3 QDs,Nano Ag,7-aminocephalosporanic acid.,Degradation,Bulk g-C3N4
更新于2025-09-19 17:15:36
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Zn2SnO4 QDs decorated Bi2WO6 nanoplates for improved visible-light-driven photocatalytic removal of gaseous contaminants
摘要： Zn 2 SnO 4 quantum dots (QDs) decorated Bi 2 WO 6 nanocomposites were prepared via a two-step hydrothermal reaction progress. The Zn 2 SnO 4 QDs were highly dispersed onto the surface of plate-shaped n-type Bi 2 WO 6 , which allows more photons to be harvested and effectively improve the separation and utilization efficiencies of photoinduced electrons and holes due to the formation of heterojunction. Among them, 3% Zn 2 SnO 4 QDs/Bi 2 WO 6 nanocomposite showed the highest photocatalytic performance (95.5% of acetone degradation), compared with other different amounts of Zn 2 SnO 4 QDs, which are 5.86 and 1.99 times higher than those of pure Bi 2 WO 6 , respectively. Meanwhile, the hybridized sample was investigated by four successive photocatalytic degradation of acetone under visible light, displaying great photo-stability. Furthermore, through in-situ FTIR, acetaldehyde, acetic acid and formaldehyde were certified as intermedias during the photocatalytic degradation of acetone. Based on these results, the relationship between photocatalytic activity and the formation of Zn 2 SnO 4 QDs/Bi 2 WO 6 heterojunction is further discussed and the possible reaction mechanism is proposed. Such novel photocatalyst as visible light responsive catalyst provides a new choice for the efficient degradation of contaminants.
关键词： Acetone,Nanocomposites,Zn 2 SnO 4 QDs/Bi 2 WO 6,In-suit FTIR
更新于2025-09-19 17:15:36
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Preparing CdS QDs in sodium alginate gel: realizing water-solubility and stimuli-responsiveness of QDs in an integrative way
摘要： Quantum dots (QDs) were of great interest due to the excellent fluorescence property and have been widely studied. Comparing with the typical organometallic synthetic routes and hydrothermal method that were usually carried out under high temperature, colloidal template could be used for preparing QDs in mild conditions and have gained increasing attention. In this prospect, hydrogel was an ideal colloidal template for preparation of QDs in aqueous medium while the related study for in-situ preparation of QDs in gel and the consequent functionalization of QDs was in demand. In this paper, we proposed a two-step method to prepare CdS QDs in sodium alginate (SA) gel which showed effective constraint in uniform size distribution of QDs. Without extra ligands introduction, the prepared CdS-SA QDs showed responsiveness to pH and detectability to Fe3+ which provide a simplified way for functionalization of QDs. The CdS-SA QDs showed good biocompatibility and stability in a certain concentration which indicated the application prospect of the CdS-SA QDs in fields of biological labeling and environmental sensor.
关键词： gel,stimuli responsiveness,pH,Sodium alginate,CdS QDs
更新于2025-09-19 17:15:36
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ZnSe/ZnS Core/shell Quantum Dots with Superior Optical Properties through Thermodynamic Shell Growth
摘要： Epitaxial growth of a protective semiconductor shell on a colloidal quantum dot (QD) core is the key strategy for achieving high fluorescence quantum efficiency and essential stability for optoelectronic applications and bio-tagging with emissive QDs. Herein we investigate the effect of shell growth rate on the structure and optical properties in blue-emitting ZnSe/ZnS QDs with narrow emission linewidth. Tuning the precursor reactivity modifies the growth mode of ZnS shells on ZnSe cores transforming from kinetic (fast) to thermodynamic (slow) growth regimes. In the thermodynamic growth regime, enhanced fluorescence quantum yields and reduced on-off blinking are achieved. This high performance is ascribed to the effective avoidance of traps at the interface between the core and the shell, which are detrimental to the emission properties. Our study points to a general strategy to obtain high-quality core/shell QDs with enhanced optical properties through controlled reactivity yielding shell growth in the thermodynamic limit.
关键词： thermodynamic,core/shell QDs,heavy-metal-free,ZnSe/ZnS,kinetic
更新于2025-09-19 17:13:59
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Shell-free Copper Indium Sulfide Quantum Dots Induce Toxicity <i>In Vitro</i> and <i>In Vivo</i>
摘要： Semiconductor quantum dots (QDs) are attractive fluorescent contrast agents for in vivo imaging due to their superior photophysical properties, but traditional QDs comprise toxic materials such as cadmium or lead. Copper indium sulfide (CuInS2, CIS) QDs have been posited as a non-toxic and potentially clinically translatable alternative; however, previous in vivo studies utilized particles with a passivating zinc sulfide (ZnS) shell, limiting direct evidence of the biocompatibility of the underlying CIS. For the first time, we assess the biodistribution and toxicity of unshelled CIS and partially zinc-alloyed CISZ QDs in a murine model. We show that bare CIS QDs breakdown quickly, inducing significant toxicity as seen in organ weight, blood chemistry, and histology. CISZ demonstrate significant, but lower, toxicity compared to bare CIS, while our measurements of core/shell CIS/ZnS are consistent with literature reports of general biocompatibility. In vitro cytotoxicity is dose-dependent on the amount of metal released due to particle degradation, linking degradation to toxicity. These results challenge the assumption that removing heavy metals necessarily reduces toxicity: indeed, we find comparable in vitro cytotoxicity between CIS and CdSe QDs, while CIS caused severe toxicity in vivo compared to CdSe. In addition to highlighting the complexity of nanotoxicity and the differences between the in vitro and in vivo outcomes, these unexpected results serve as a reminder of the importance of assessing the biocompatibility of core QDs absent the protective ZnS shell when making specific claims of compositional biocompatibility.
关键词： in vivo imaging,biodegradable,CIS,nanotoxicity,nanomedicine,CuInS2,fluorescent contrast agent,QDs
更新于2025-09-19 17:13:59
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InP-Based Quantum Dots Having an InP Core, Composition-Gradient ZnSeS Inner Shell, and ZnS Outer Shell with Sharp, Bright Emissivity and Blue Absorptivity for Display Devices
摘要： Indium phosphide (InP) has been regarded as the most promising composition of visible quantum dot (QD) emitters for the application to next-generation display devices primarily due to its environmental benignity. Bright, sharp emissivity of InP QDs should be pursued for the realization of high-efficiency, wide-color gamut display devices. Photoluminescence (PL) performance of InP QDs has been greatly improved based on synthetic advances enabling the securement of core size homogeneity and the formation of exquisite core/shell heterostructure. Till now high-quality fluorescent InP QDs have been attainable exclusively with use of a hazardous phosphorus (P) precursor of tris(trimethylsilyl)phosphine ((TMS)3P) against green chemistry. In this work we report a synthetic breakthrough of green InP QDs towards narrow, bright emissivity by using a much cheaper, safer P alternative of tris(dimethylamino)phosphine ((DMA)3P). For this, QD synthesis proceeds via so-called two-step approach, where as-grown InP cores are subjected to a stepwise size fractionation process and then placed in the consecutive double shelling of composition-gradient ZnSexS1-x inner and ZnS outer shell. The chemical composition (x) of ZnSexS1-x inner shell in the range of 0.09?0.36 is varied to explore its effects on PL quantum yield (QY), size, and blue excitation light absorptivity. Owing to the effective core size fractionation and elaborately designed heterostructure the resulting InP/ZnSexS1-x/ZnS QDs exhibit exceptional green (527 nm) PL features of a sharp line width of 37 nm and a high PL QY of 87%, which have been never achievable to date from non-(TMS)3P-based QDs, when an optimal inner shell composition is applied.
关键词： double shelling,InP QDs,PL QY,sharp line width,size fractionation,phosphorus precursor
更新于2025-09-19 17:13:59