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Colloidally Stable Monolayer Nanosheets with Colorimetric Responses
摘要： Despite the discovery of chromogenic-layered materials for decades of years, fabrication of colloidally stable monolayer organic 2D nanosheets in aqueous media with colorimetric responses is still challenging. Herein reported is the first solution synthesis of chromic monolayer nanosheets via the topochemical polymerization of self-assembled amphiphilic diacetylenes in aqueous media. The polydiacetylene (PDA) nanosheets are ≈3–4 nm thick in solution and only ≈1.9 nm thick in the dried state, while the lateral size can reach several micrometers. Moreover, the aqueous stability endows PDA nanosheets with excellent processability, which can further assemble into films via vacuum filtration or act as an ink for high-resolution inkjet printing. The filtrated films and printed patterns exhibit fully reversible blue-to-red thermochromism, and the film also displays an interesting reversible colorimetric transition in response to near-infrared light, which is not reported for other PDA-only systems. The present colloidal PDA nanosheets should represent a new kind of chromic organic 2D nanomaterials that may be applied as novel building blocks for developing intelligent hybrid materials and may also find diverse sensing, display and/or anticounterfeiting applications.
关键词： colorimetric responses,monolayer nanosheets,colloidal stability,polydiacetylene
更新于2025-09-23 15:23:52
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Interfacial Contact is Required for Metal-Assisted Plasma Etching of Silicon
摘要： For decades, fabrication of semiconductor devices has utilized well-established etching techniques to create complex nanostructures in silicon. The most common dry process is reactive ion etching which fabricates nanostructures through the selective removal of unmasked silicon. Generalized enhancements of etching have been reported with mask-enhanced etching with Al, Cr, Cu, and Ag masks, but there is a lack of reports exploring the ability of metallic films to catalytically enhance the local etching of silicon in plasmas. Here, metal-assisted plasma etching (MAPE) is performed using patterned nanometers-thick gold films to catalyze the etching of silicon in an SF6/O2 mixed plasma, selectively increasing the rate of etching by over 1000%. The catalytic enhancement of etching requires direct Si-metal interfacial contact, similar to metal-assisted chemical etching (MACE), but is different in terms of the etching mechanism. The mechanism of MAPE is explored by characterizing the degree of enhancement as a function of Au catalyst configuration and relative oxygen feed concentration, along with the catalytic activities of other common MACE metals including Ag, Pt, and Cu.
关键词： nanofabrication,MACE,silicon processing,reactive ion etching,metal assisted etching
更新于2025-09-23 15:23:52
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Comparative solvent quality dependent crystallization in solvent vapor annealing of P3HT:PCBM thin films by in-situ GIWAXS
摘要： We present a novel in-depth study correlating multiple solvent properties (boiling point, vapor pressure, and solubilities of P3HT and PCBM) on P3HT and PCBM crystal growth kinetics in blend thin films via in-situ GIWAXS in conjunction with multiple substrate energies. Solvent vapor annealed (SVA) P3HT:PCBM films in a closed chamber, saturated with different solvents (o-dichlorobenzene (DCB), o-xylene, tetrahydrothiophene (THT), toluene, benzene, tetrahydrofuran (THF), and carbon disulfide (CS2)) were studied in real time. We observed that structure growth and dissolution kinetics of the both P3HT and PCBM crystals largely depend on physical properties of solvent and relative solubilities of P3HT and PCBM. The film morphology of the annealed films resulted in PCBM enrichment and occasional crystallization occurred at the solvent vapor saturated air interfaces. We observed strikingly different PCBM crystallization upon annealing of the films when cast from THF resulting in highly ordered PCBM crystals at the film surface. THF has high vapor pressure and relatively low solubilities for both P3HT and PCBM. At the other extreme CS2 produced the lowest crystallinity due to its very high vapor pressure such that the solvent evaporates before significant crystallization can occur. We characterized all the annealed samples using AFM, UV-Vis spectroscopy, and XPS. AFM probed topographic structures with coarsening of both the P3HT and PCBM domains at air surface by solvent annealing. We observe via UV-vis spectroscopy that, in general, intrachain electronic delocalization and interchain electron transitional jump due to π-π stacking increases in the post SVA films. This indicates that the chains are better organized with increased conjugation lengths. SVA has a substantial effect on P3HT monomer to PCBM ratio as determined by XPS at the polymer-air interface. In all cases, relative to the P3HT monomer:PCBM ratio of as-cast films from DCB, the air surfaces became more enriched by PCBM with SVA.
关键词： P3HT,GIWAXS,Morphology
更新于2025-09-23 15:23:52
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One-Pot Synthesis of Pd-Based Ternary Pd@CdS@TiO <sub/>2</sub> Nanoclusters via a Solvothermal Route and Their Catalytic Reduction Efficiency toward Toxic Hexavalent Chromium
摘要： In this work, we report the synthesis of Pd-based ternary Pd@CdS@TiO2 nanocomposites using molecular precursors. This method is facile, less time-consuming, and cost-effective. This catalyst is prepared within 2 h by a solvothermal route using molecular precursors. Information about the phase, morphologies, elemental mapping, and composition of the nanocomposites was obtained using various characterization techniques. The catalytic activity of the as-prepared Pd-based ternary Pd@CdS@TiO2 nanocomposites exhibits effective reduction efficiency for the conversion of toxic Cr(VI) to Cr(III) using formic acid as a reducing agent within 5?7 min. To the best of our knowledge, this is the first report on Pd-based ternary Pd@CdS@TiO2 nanocomposites prepared by a solvothermal route and used as catalysts toward the reduction of hexavalent chromium at room temperature.
更新于2025-09-23 15:23:52
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Creation of passivated Nb/N p-n co-doped ZnO nanoparticles and their enhanced photocatalytic performance under visible light illumination
摘要： Passivated niobium/nitrogen (Nb-N) p-n co-doped zinc oxide nanoparticles were created by a simple precipitation process with in-situ self-formed NaCl "cage" to confine the nanoparticle growth followed by the heat treatment in a flow of ammonia gas. Enhanced optical absorbance into the visible light region was observed in the Nb/N co-doped ZnO nanoparticle photocatalyst due to the Nb/N co-doping effect. It demonstrated a largely enhanced photocatalytic performance in the disinfection of Escherichia coli bacteria under visible light illumination, which could be attributed to the passivated co-doping of Nb-N to suppress the photogenerated charge carrier recombination on dopants. This robust approach for passivated p-n co-doping may also be applied to other material systems for a wide range of technical applications.
关键词： Nanoparticles,Passivated Nb/N p-n Co-doping,Photocatalyst,Zinc oxide,Visible light
更新于2025-09-23 15:23:52
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New heteroleptic iridium(III) nitro complexes derived from fac-[Ir(NO2)3(H2O)3]
摘要： An aqueous solution of fac-[Ir(H2O)3(NO2)3] (1) was utilized as a starting material for preparation of the new heteroleptic iridium complex [Ir(H2O)(bpy)(NO2)3] (2). From alkaline solutions of 2, the salt Na[Ir(OH)(NO2)3(bpy)]·2H2O was isolated and its structure was determined by X-ray structure analysis. Structures of new compounds 2 and 3 as well as the parent complex 1 was characterized using multinuclear magnetic resonance spectroscopy and mass spectrometry. The structures of parent fac-[Ir(H2O)3(NO2)3] and complexes 2 and 3 were probed by employing density functional theory (DFT) calculations.
关键词： Nitrocomplexes,Iridium,DFT,NMR,Aquacomplexes,X-ray structure
更新于2025-09-23 15:23:52
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Low-Temperature Plasma-Enhanced Atomic Layer Deposition of Tin(IV) Oxide from a Functionalized Alkyl Precursor: Fabrication and Evaluation of SnO <sub/>2</sub> -Based Thin-Film Transistor Devices
摘要： A bottom-up process from precursor development for tin to plasma-enhanced atomic layer deposition (PEALD) for tin(IV) oxide and its successful implementation in a working thin-film transistor device is reported. PEALD of tin(IV) oxide thin films at low temperatures down to 60 °C employing tetrakis-(dimethylamino)propyl tin(IV) [Sn(DMP)4] and oxygen plasma is demonstrated. The liquid precursor has been synthesized and thoroughly characterized with thermogravimetric analyses, revealing sufficient volatility and long-term thermal stability. [Sn(DMP)4] demonstrates typical saturation behavior and constant growth rates of 0.27 or 0.42 ? cycle?1 at 150 and 60 °C, respectively, in PEALD experiments. Within the ALD regime, the films are smooth, uniform, and of high purity. On the basis of these promising features, the PEALD process was optimized wherein a 6 nm thick tin oxide channel material layer deposited at 60 °C was applied in bottom-contact bottom-gate thin-film transistors, showing a remarkable on/off ratio of 107 and field-effect mobility of ≈ 12 cm2 V?1 s?1 for the as-deposited thin films deposited at such low temperatures.
关键词： thin-film transistors,tin(IV) oxide,thin films,precursors,atomic layer deposition
更新于2025-09-23 15:23:52
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Universal existence of fluorescent carbon dots in beer and assessment of their potential toxicity
摘要： Nanosized materials may produce adverse physiological effects or potential health risks due to their unique physical and chemical properties. Herein, the universal presence of fluorescent carbon dots (CDs) in commercial beers was confirmed through a systematic survey. The beer CDs were roughly spherically shaped in appearance and emitted bright blue fluorescence under ultraviolet light with quantum yields (QYs) ranging from 1.42% to 3.92%. Furthermore, digestion, biodistribution, and cytotoxicity assessments of CDs from Snow beer were conducted as an example. The CDs were significantly quenched during in vitro digestion. The dynamic distribution of CDs in mice showed that they easily accumulated in the intestine and liver, and more importantly, the beer CDs were found in the brain, which indicated that they were able to cross the blood–brain barrier. Acute toxicity of the beer CDs was evaluated using BALB/c mice, and the results revealed that the biochemical parameters of mice after administration of a single dose of 2 g kg?1 body weight were almost same as those of the control groups. Histological analysis showed no obvious organ damage in the tested mice. The in vitro results indicated that CDs dispersed onto both the cell membrane and the cytoplasm of MC3T3-E1 cells, alter the cell cycle progression, and caused cell apoptosis at high doses. This work reports the potential risk of CDs in beer and provides valuable information regarding CDs in food.
关键词： beer,cytotoxicity,biodistribution,Carbon dots,digestion
更新于2025-09-23 15:23:52
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Electrochemical and Electrochromic Properties of Polymers Based on 2,5-di(2-thienyl)-1H-pyrrole and Different Phenothiazine Units
摘要： Three new 2, 5-di(2-thienyl)-1H-pyrrole(DTP) derivatives, 10-[4-(2,5-Di-thiophen-2-yl-pyrrol-1-yl)-phenyl]-10H-pheno-thiazine (TPPT), 10-[4-(2,5-Di-thiophen-2-yl-pyrrol-1-yl)-phenyl]-10H-phenoxazine (TPPO) and 10-[4-(2,5-Di-thiophen-2-yl-pyrrol-1-yl)-phenyl]-10H-acridin-9-one (TPAO), were synthesized and characterized. TPPT and TPPO showed similar absorption and emission feature owing to similar chemical structure, TPAO displayed bathochromic-shift for both absorption and emission feature due to the existence of ketone group. All the monomers could be electropolymerized to form their polymer film on the electrode surface via oxidative coupling reactions of DTP units. PTPPT film showed yellow-green, green and purple red color upon different applied potentials. PTPPO and PTPAO films exhibited green and yellow at the neutral state, respectively, and turned into the similar violet color for the oxidized state. Moreover, the copolymer P(TPPT/EDOT) and P(TPAO/EDOT) not only showed obvious color change(red, yellow, green and blue), but also possessed better electrochemical stability.
更新于2025-09-23 15:22:29
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Enhanced Persistence Properties through Modifying the Trap Depth and Density in Y <sub/>3</sub> Al <sub/>2</sub> Ga <sub/>3</sub> O <sub/>12</sub> :Ce <sup>3+</sup> ,Yb <sup>3+</sup> Phosphor by Co-doping B <sup>3+</sup>
摘要： Long persistence phosphors with high emitting intensity are promising materials for safety signage and energy storage applications. Herein, an improved persistent luminescence of Y3Al2Ga3O12 phosphor by co-doping Ce3+, Yb3+, and B3+ is achieved using conventional solid-state reaction. On one hand, the incorporation of H3BO3 can improve the crystallinity; on the other hand, B3+ can replace Al3+/Ga3+ in tetrahedral sites in the host lattice, causing lattice contraction and modifying the trap depth and density. It is found that adding B3+ forms a much deeper trap with ～1.10 eV depth. In addition, the density of the electron trap can also be dramatically increased compared to the sample without B3+. The charging process for persistent luminescence is demonstrated by comparing the photoluminescence excitation spectrum with the thermoluminescence excitation spectrum. The persistence luminescence mechanism is given by a visual energy level diagram on the basis of the vacuum referred binding energy scheme of Y3Al2Ga3O12.
更新于2025-09-23 15:22:29