Injection Of Precursor Research Articles

Production of Ag nanowires with high yield and narrow size distribution by promoting nucleation through hot injection and their application to disposable paper electrodes

The polyol method has been the most commonly used technique for fabricating silver nanowires (Ag NWs), wherein additive reagents facilitate precise control over their morphology. In this work, we introduced a straightforward approach to synthesize Ag NWs with minimal impurities and uniform diameter by using hot injection method. The underlying mechanism and final product are evaluated, and the scalable process was optimized to achieve a high yield (∼87.8 %). It was found that the hot injection of a Ag precursor at 170 °C significantly accelerated the reduction of Ag ions. The issue of the uniformity of Ag NWs was addressed by adding an organic halide to control the nucleation rate of Ag. The resulting Ag NWs solution was used to impregnated cellulose paper, forming an enhanced electrical network compared to other substrates. Given the low commercial cost of paper, this approach holds significant potential for widespread use in disposable electrodes. Furthermore, after subjecting the fabricated paper electrodes to various forms of damage, the connected LED bulbs consistently maintained their brightness. This demonstrates the network stability and suitability of these electrodes for flexible applications.

Mn derived growth of CsPbBr3 nanoplatelets for stable and bright orange emission

Abstract Mn-doped perovskites have been extensively studied in optics, magnetism, and electronics due to their orange emission. However, successful Mn doping required a high Mn/Pb feed ratio. In this paper, Mn-doped CsPbBr3 nanoplatelets (NPLs) with bright orange emission were prepared by a two-step slow thermal injection synthesis. The slow injection of precursors effectively slow-down the crystal growth kinetic process and controls the growth of undoped CsPbBr3 NPLs. This process also significantly improves Mn doping efficiency. Mn doping induced the generation of numerous precursor clusters during the growth of CsPbBr3 NPLs, and the formation of these clusters was crucial for enhancing the doping efficiency. The maximum amount of Mn precursor in CsPb0.83Mn0.17Br3 was 50% of Pb precursors. The photoluminescence quantum yields (PLQYs) of CsPb0.94Mn0.06Br3 NPLs reached up to 80.6%, which was 3.1 times of that of CsPbBr3 NPLs. The PL properties of Mn-doped CsPbBr3 NPLs were significantly enhanced compared with pure CsPbBr3 NPLs. The growth process and luminescence mechanism of Mn-doped CsPbBr3 NPLs were discussed. High PLQYs and efficient Mn doping supplied an ideal approach for the preparation of various CsPbX3 (X = Cl, Br, and I) NCs for commercial applications.

Reducing contact resistance of MoS2-based field effect transistors through uniform interlayer insertion via atomic layer deposition.

Molybdenum disulfide (MoS2), a semiconducting two-dimensional layered transition metal dichalcogenide (2D TMDC), with attractive properties enables the opening of a new electronics era beyond Si. However, the notoriously high contact resistance (RC) regardless of the electrode metal has been a major challenge in the practical applications of MoS2-based electronics. Moreover, it is difficult to lower RC because the conventional doping technique is unsuitable for MoS2 due to its ultrathin nature. Therefore, the metal-insulator-semiconductor (MIS) architecture has been proposed as a method to fabricate a reliable and stable contact with low RC. Herein, we introduce a strategy to fabricate MIS contact based on atomic layer deposition (ALD) to dramatically reduce the RC of single-layer MoS2 field effect transistors (FETs). We utilize ALD Al2O3 as an interlayer for the MIS contact of bottom-gated MoS2 FETs. Based on the Langmuir isotherm, the uniformity of ALD Al2O3 films on MoS2 can be increased by modulating the precursor injection pressures even at low temperatures of 150 °C. We discovered, for the first time, that film uniformity critically affects RC without altering the film thickness. Additionally, we can add functionality to the uniform interlayer by adopting isopropyl alcohol (IPA) as an oxidant. Tunneling resistance across the MIS contact is lowered by n-type doping of MoS2 induced by IPA as the oxidant in the ALD process. Through a highly uniform interlayer combined with strong doping, the contact resistance is improved by more than two orders of magnitude compared to that of other MoS2 FETs fabricated in this study.

Effect of Nanoplatelets Thickness on Photoluminescent, Optical, and Electronic Properties of Synthesized CdTe Semiconductor Nanoplatelets

Quantum-confined CdTe nanoplatelets (NPL) are synthesized in colloidal solutions. The formation, growth, and transformation of 2D NPLs are monitored using UV-visible absorption PL spectroscopy and transmission electron microscopy. The luminescence intensity of NPL dependences on the temperature and injection of precursors is shown. It is found that the luminescence spectra shift to the long-wavelength region with increasing temperature due to an increase in the thickness of the NPL. The dependence of the band gap on the thickness of the NPL is shown. The band gap is determined by the thickness and number of layers. The dependence of the concentration of precursors in the reaction mass and the kinetics of NPL growth are shown. The excitation of defect states luminescence depends on the coordinating oleic ligand. The crystal structure of the CdTe NPL was analyzed via the electron diffraction pattern (ED), which allows a comparative conclusion about the crystal structure of the obtained NPL samples.

Continuous-Flow Chemical Synthesis for Sub-2 nm Ultra-Multielement Alloy Nanoparticles Consisting of Group IV to XV Elements.

Multielement alloy nanoparticles have attracted much attention due to their attractive catalytic properties derived from the multiple interactions of adjacent multielement atoms. However, mixing multiple elements in ultrasmall nanoparticles from a wide range of elements on the periodic table is still challenging because the elements have different properties and miscibility. Herein, we developed a benchtop 4-way flow reactor for chemical synthesis of ultra-multielement alloy (UMEA) nanoparticles composed of d-block and p-block elements. BiCoCuFeGaInIrNiPdPtRhRuSbSnTi 15-element alloy nanoparticles composed of group IV to XV elements were synthesized by sequential injection of metal precursors using the reactor. This methodology realized the formation of UMEA nanoparticles at low temperature (66 °C), resulting in a 1.9 nm ultrasmall average particle size. The UMEA nanoparticles have high durability and activity for electrochemical alcohol oxidation reactions and high tolerance to CO poisoning. These results suggest that the multiple interactions of UMEA efficiently promote the multistep alcohol oxidation reaction.

Digitizing protocols into single reactors for the one-pot synthesis of nanomaterials

Digitizing protocols into single reactors for the one-pot synthesis of nanomaterials

Composition-Dependent Optical Properties of Cu–Zn–In–Se Colloidal Nanocrystals Synthesized via Cation Exchange

Copper chalcogenide-based nanocrystals (NCs) are a suitable replacement for toxic Cd/Pb chalcogenide-based NCs in a wide range of applications including photovoltaics, optoelectronics, and biological imaging. However, despite rigorous research, direct synthesis approaches of this class of compounds suffer from inhomogeneous size, shape, and composition of the NC ensembles, which is reflected in their broad photoluminescence (PL) bandwidths. A partial cation exchange (CE) strategy, wherein host cations in the initial binary copper chalcogenide are replaced by incoming cations to form ternary/quaternary multicomponent NCs, has been proven to be instrumental in achieving better size, shape, and composition control to this class of nanomaterials. Additionally, adopting synthetic strategies which help to eliminate inhomogeneities in the NC ensembles can lead to narrower PL bandwidths, as was shown by single-particle studies on I–III–VI2-based semiconductor NCs. In this work, we formulate a two-step colloidal synthesis of Cu–Zn–In–Se (CZISe) NCs via a partial CE pathway. The first step is the synthesis of Cu2–xSe NCs, which serve as a template for the subsequent CE reaction. The second step is the incorporation of the In3+ and Zn2+ guest cations into the synthesized Cu2–xSe NCs via simultaneous injection of both metal precursors, which results in gradient-alloyed CZISe NCs with a Zn-rich surface. The as-synthesized NCs exhibit near-infrared (NIR) PL without an additional shell growth, which is typically required in most of the developed protocols. The photoluminescence quantum yield (PLQY) of these Cu chalcogenide-based NCs reaches 20%. These NCs also exhibit intriguingly narrow PL bands, which challenges the notion of broad PL bands being an inherent property of this class of NCs. Additionally, a variation in the feed ratios of the incoming cations, i.e., In/Zn, results in the variation of the composition of the synthesized NCs. Henceforth, the optical properties of these NCs could be tuned by a simple variation of the composition of the NCs achieved by varying the feed ratios of the incoming cations. Within a narrow size distribution, the PL maxima range from 980 to 1060 nm, depending on the composition of the NCs. Post-synthetic surface modification of the synthesized NCs enabled the replacement of the parent long-chain organic ligands with smaller species, which is essential for their prospective applications requiring efficient charge transport. With PL emission extended into the NIR, the synthesized NCs are suitable for an array of potential applications, most importantly in the area of solar energy harvesting and bioimaging. The large Stokes shift inherent to these materials, their absorption in the solar range, and their NIR PL within the biological window make them suitable candidates.

A Novel Molecular Reservoir Based on Reverse Self-Assembled Liquid Crystals - A New Strategy for Prolonging the Duration in Action of Analgesics

PurposeThe aim of this study was to develop liquid crystal (LC) precursors to obtain novel long-acting analgesics for injection based on depot systems and compare the difference between the cubic and hexagonal precursors in delivering Diclofenac sodium (DS). MethodsDiclofenac sodium liquid crystal precursor injections were prepared and characterized, followed by in vitro release, pharmacodynamic, and pharmacokinetic studies. ResultsThe optimal formulations were prepared with a ratio of Phytantriol/ethanol/water as 76:19:5 for cubic LC precursors, and a ratio of Phytantriol/ethanol/water/Vitamine-E acetate as 72:18:5:5 for hexagonal, both loading various drug dosages (2.5%, 3.75% and 5%), respectively. Polarized light microscopy and small angle diffraction confirmed that the precursors were isotropic fluids and transformed into gels with Pn3m or HII framework in water. Rheological studies have shown that precursors belong to Newtonian fluids and gels to pseudoplastic fluids. The release showed that the DS in the commercial injection (DS-inj) was completely liberated within 6 h, whereas only 46.55% and 49.73% of the DS in 2.5% cubic precursors and 2.5% hexagonal precursors were freed, respectively. Pharmacodynamic studies have shown that cubic, hexagonal and DS-inj raised the pain threshold in mice by 169.4%, 157.3% and 113.79%, respectively. The mean retention times of DS in cubic and hexagonal were 3.16 and 2.67 times longer than DS-inj, respectively, according to pharmacokinetic results. ConclusionIn conclusion, cubic and hexagonal are both promising analgesic sustained release formulations. In addition, based only on the current comparison, cubic seems to have a better long-acting effect.

Conformal Growth of Hexagonal Boron Nitride on High-Aspect-Ratio Silicon-Based Nanotrenches

We successfully accomplished the conformal growth of sp2-hybridized few-layer h-BN over an array of Si-based nanotrenches with a 45 nm pitch and an aspect ratio of ∼7:1 by using the pulsed-mode metal–organic chemical vapor deposition (MOCVD) method. Surface-sensitive X-ray absorption fine structure spectroscopy and density functional theory calculations revealed that the B–O bonds formed on the noncatalytic SiO2 surface act as nucleation sites for the subsequential formation of mixed sp2- and sp3-hybridized BON2 and BN3 at the very initial stage of the pulsed-mode injection of MOCVD precursors, enabling the conformal growth of few-layer sp2-hybridized h-BN with an excellent step coverage. We believe that these results can provide a broad avenue for the implementation of fascinating two-dimensional layered materials for current state-of-the-art three-dimensional Si-based nanoscale architectures, overcoming the downscaling limits.

Highly Monodisperse PbS Quantum Dots with Facet Engineering for High-Radiance Light-Emitting Diodes in the NIR-II Window

Solution-processed PbS quantum dot light-emitting diodes (QLEDs) with emission in the second near-infrared window (NIR-II, 1100–1700 nm) are excellent candidates as light sources for optical communication, night vision, and biomedical monitoring. However, it is still a tremendous challenge to achieve high-radiance PbS QLEDs due to serious QD surface traps and unbalanced charge injection. Herein, highly monodisperse PbS QDs with tailored facet growth were successfully synthesized by the continuous precursor injection method. The synthesized PbS QDs revealed a tunable absorption peak from 1200 to 1700 nm with a supernarrow full width at half-maximum (fwhm; <105 nm). The tailored surface facet growth effectively decreased the nonpolar (100) facet and surface defects. Furthermore, with a multilayered organic–inorganic hybrid architecture of indium tin oxide (ITO)/poly(ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS)/poly(9,9-dioctylfluorene-co-N-(4-(3-methylpropyl))-diphenylamine) (TFB)/PbS QDs/ZnO/Al, the novel infrared PbS QLED exhibited an excellent maximum radiance of 16.14 W sr–1 m–2 at 6.15 V with a shortwave-infrared electroluminescence at ∼1530 nm. Importantly, the NIR-II QLEDs using facet-tailored PbS QDs with the EL peak between 1100 and 1700 nm represented extremely high radiances. The excellent performances are ascribed to the passivated PbS QDs with a tailored surface facet and the hybrid device structure for charge injection balance. This work provides an effective approach for the preparation of high-quality PbS QDs and is expected to significantly boost the potential commercial applications of PbS NIR-II QLEDs.

On-Demand Changeable Theranostic Hydrogels and Visual Imaging-Guided Antibacterial Photodynamic Therapy to Promote Wound Healing.

Antibacterial wound dressings are confronted with the challenges in real-time imaging of infected wounds and effective removal of bacterial debris after sterilization to promote the healing process. Herein, injectable theranostic hydrogels were constructed from antimicrobial peptide ε-polylysine (ePL) and polydopamine (PDA) nanoparticles for real-time diagnosis of infected wounds, imaging-guided antibacterial photodynamic therapy (PDT), and on-demand removal of bacterial debris. Ureido-pyrimidinone was conjugated on ePL to produce PLU hydrogels through quadruple hydrogen bonding, and the inoculation of tetrakis(4-carboxyphenyl)porphyrin (TCPP)-loaded PDA (PTc) nanoparticles introduced Schiff base linkages in PLU@PTc hydrogels. The double-cross-linked networks enhance mechanical performance, adhesion strength, and self-healing properties of hydrogels, and the dynamic cross-linking enables their photothermal removal. The injection of PLU precursors and PTc NPs generates in situ sol-gel transformation, and the acid-triggered release of TCPP restores fluorescence emissions for real-time imaging of infected wounds under 410 nm illumination. Then, the released TCPP in the infected wounds is illuminated at 660 nm to launch a precise antibacterial PDT, which is strengthened by the bacterial capture on hydrogels. Hydrogels with wrapped bacterial debris are removed under illumination at 808 nm, and the hydrogel dressing change accelerates healing of infected wounds through simultaneous relief of oxidative stress, regulation of inflammatory factors, acceleration of collagen deposition, and promotion of angiogenesis. Thus, this study demonstrates a feasible strategy for wound infection theranostics through bacterial infection-triggered visual imaging, efficient nonantibiotic sterilization, and on-demand dressing change and bacterial debris removal.

Low-Temperature Deposition of Yttrium Oxide on Flexible PET Films Using Time-Separated Yttrium Precursor and Oxidizer Injections

Low-Temperature Deposition of Yttrium Oxide on Flexible PET Films Using Time-Separated Yttrium Precursor and Oxidizer Injections

One-Step Synthesis of Dynamically Shaped Stiff Nanorods Using Soft Silicone Materials to Control Water Repulsion and Collection.

One-dimensional silicone nanostructures, such as filaments, wires, and tubes, have attracted significant attention, owing to their remarkable application capabilities in a large range of material and surface science. However, the soft mechanical properties of silicone cause vulnerability and irregularity in the synthesized structures, which limits their applications. Herein, a simple, solvent-free, and efficient dynamic Droplet Assisted Growth and Shaping (d-DAGS) strategy is proposed for the one-step synthesis and in situ control of the shape of silicone nanostructures. The special designed bamboo-shaped silicone nanorods (SNRs) that are produced by the repetitive dynamic regulation of growth conditions, concomitant with the periodic purging and injection of precursors, exhibit highly-regular and tunable structure with a specific number of segments, indicating that they can be tailor-made according to the requirements of various properties. The enhanced mechanical stiffness and chemical durability strongly support their excellent performances in water-resistance under both static and dynamic wetting conditions. The SNRs significantly promote buoyancy and self-cleaning properties; and exhibit very high water-harvesting efficiency compared with existing designs. Notably, the well-structured ultra-long rods with an ultrahigh aspect ratio (≈176) can also be fabricated by the d-DAGS method, and they can remain standing straight upwards and regular, even though they consist of flexible silicone.

Growth of ultrathin barrier InAlGaN/GaN heterostructures with superior properties using sputtered AlN/sapphire templates and optimized group-III injection rate by metalorganic chemical vapor phase deposition

In this paper, we investigate the influence of group-III precursor injection rate on the material and electrical properties of InAlGaN/GaN heterostructures grown by Metalorganic Chemical Vapor Phase Deposition. It is demonstrated that high-quality GaN layers can be achieved by using the sputtered AlN/sapphire templates. During the barrier layer growth, the injection rate of the Trimethylindium plays an important role in the amount of Ga incorporation into the InAlGaN layer, while the variation of Trimethylaluminum has less impact. High mobility of 1800 cm2/(V·s) and high carrier electron density with an ultrathin of 3 nm thickness InAlGaN barrier layer simultaneously maintaining high crystallinity and smooth surface of InAlGaN barrier layer is achieved with sputtered AlN/sapphire templates and optimized group-III injection rate.

Ultrathin scroll-like CdSe/CdS core/crown heteronanoplatelets: Colloidal synthesis and properties

We report the synthesis and the optical properties of a new type of scroll-like CdSe/CdS core/crown nanoplatelets (NPLs), based on the ultrathin rolled-up CdSe core NPLs with the laterally epitaxial grown of CdS crowns. This typical synthesis pathway is explored by optimizing crowns growth temperatures and precursor injection conditions by a high-efficiency one-step strategy, thus controlling the ultrathin thickness of scrolled CdS crowns at the monolayer level. These novel ultrathin nanoroll-like core/crown NPLs not only have excellent optical properties with the ultra-narrow emission spectra, but also given the improved photoluminescence efficiency and enhanced photostability in the blue light region. Importantly, the broad trap emission in core/crown hetero-NPLs is completely suppressed by a photo-annealing process, which could avoid the significant adverse effects on intrinsic emission and keep their emission intensity of ~90%. Therefore, this work proposes a useful strategy for synthesizing ultrathin scrolled core/crown NPLs heterostructures, which paves the way for fabricating high-efficiency and stable ultrathin NPL-based heterostructure materials in the blue-violet emission band.

Effect of Different Carbon Supports on the Activity of PtNi Bimetallic Catalysts toward the Oxygen Reduction

To evaluate supports’ effects on catalytic activity toward the oxygen reduction reaction (ORR), a simple and controlled chemical synthesis, involving the hot injection of metal precursors, was developed to produce bimetallic PtNi nanoparticles (75 wt.% Pt and 25 wt.% Ni), supported on carbon nanotubes (CNTs) and carbon nanofibers (CNFs). The synthesized electrocatalyst was characterized using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and scanning transmission electron microscopy (STEM). To determine the catalytic activity, an electrochemical evaluation of the synthesized catalysts in an acidic medium was performed using cyclic voltammetry (CV), CO stripping, and rotating disk electrode (RDE) tests. The presence of Pt and Ni in the nanoparticles was confirmed by EDS and XRD. Based on the STEM micrographs, the average particle size was 30 nm. Compared to the commercial Pt/C catalyst, the PtNi/CNT catalyst exhibited higher specific activity and slightly lower mass activity toward ORR in a 0.1 M HClO4 electrolyte solution.

Injectable hydrogels for bone and cartilage tissue engineering: a review.

Tissue engineering, using a combination of living cells, bioactive molecules, and three-dimensional porous scaffolds, is a promising alternative to traditional treatments such as the use of autografts and allografts for bone and cartilage tissue regeneration. Scaffolds, in this combination, can be applied either through surgery by implantation of cell-seeded pre-fabricated scaffolds, or through injection of a solidifying precursor and cell mixture, or as an injectable cell-seeded pre-fabricated scaffold. In situ forming and pre-fabricated injectable scaffolds can be injected directly into the defect site with complex shape and critical size in a minimally invasive manner. Proper and homogeneous distribution of cells, biological factors, and molecular signals in these injectable scaffolds is another advantage over pre-fabricated scaffolds. Due to the importance of injectable scaffolds in tissue engineering, here different types of injectable scaffolds, their design challenges, and applications in bone and cartilage tissue regeneration are reviewed.

Aerosol‐assisted open‐air plasma deposition of acrylate‐based composite coatings: Molecule release control through precursor selection

AbstractAerosol‐assisted open‐air plasma allows the direct deposition of composite coatings with embedded bioactive agents. However, the deposition of biodegradable coatings for controlled drug release application remains challenging. In this study, an innovative precursor injection strategy is used to entrap tracers in coatings deposited from various acrylate‐based precursors: Acrylic acid (AA), methacrylic anhydride (MA), and 1,4‐butanediol diacrylate (BDDA). Water immersion tests show dramatically different release kinetics ranging from over minutes to weeks and months for AA, MA, and BDDA, respectively. These different behaviors are correlated to the crosslinking degree and the hydrolysis rates of the crosslinking functions. This original approach allows controlled release of tracers entrapped in biodegradable acrylate‐based coatings and provides new insights for drug‐release application.

Flow-modulated deposition of sp2-boron nitride using diborane and ammonia on chemomechanically polished (0001) 4H-SiC substrates

Nanocrystalline sp2-BN thin films have been grown on (0001) 4H-SiC substrates at 1030 °C via continuous flow and discontinuous flow-modulated chemical vapor deposition techniques using diborane (B2H6) and ammonia (NH3) as the B and N sources, respectively. The latter technique enabled observations of both the effect of hydrogen purge steps between precursor injections and the length of injection times for B2H6 on the stoichiometry and microstructure of the films. Stoichiometric BN was achieved in all films grown continuously within the N/B gas phase ratio range of 20–200; this was not observed for the discontinuously grown films unless both the B2H6 flow rate and the injection time were minimized. Cross-sectional transmission electron microscopy of films grown both continuously and discontinuously at N/B = 200 and using short B2H6 injection times relative to that of NH3 for the latter process route revealed the initial growth of ∼4 nm thick partially ordered sp2-BN layers. A transition zone then formed containing randomly oriented polycrystalline grains. Excess B incorporated into the discontinuously grown films during long B2H6 injection times resulted in single layer mixtures of amorphous and sp2-BN without any observed ordering.

The regulatory role of nitric oxide in morphine-induced analgesia in the descending path of pain from the dorsal hippocampus to the dorsolateral periaqueductal gray.

Nitric oxide (NO) levels in brain nuclei, such as the hippocampus and brainstem, are involved in morphine analgesia, but the relationship between the dorsal hippocampus (dH) and the dorsolateral periaqueductal gray matter (dlPAG) needs to be clarified, which is our goal. Wistar rats were simultaneously equipped with a stereotaxic device with unilateral guide cannula at dH and dlPAG. After recovery, they were divided into control and experimental groups. Formalin (50μl of 2.5%) was inoculated into the left hind paw of the rat. Morphine (6mg/kg) was administered intraperitoneally (i.p.) 10min before formalin injection. L-Arginine (0.25, 0.5, 1 and 2μg/rat), and L-NAME (0.25, 0.5, 1 and 2μg/rat), unrelatedly or with respect in the order of injection were used in the nuclei before morphine injection (i.p.). Activation of the neuronal NO synthase (nNOS) in the brains of all animals was measured using NADPH-diaphorase, a selective biochemical marker of nNOS. Morphine reduced inflammatory pain in the early and late stages of the rat formalin test. The morphine response was attenuated before injection of single L-arginine but not L-NAME in the two target areas. However, the acute phase result was stopped due to L-NAME pretreatment. When L-NAME was injected into dlPAG before injecting L-arginine at dH, the morphine response did not decrease at all, indicating a modulatory role of NO in dlPAG, which was confirmed by NADPH-d staining. High levels of NO in dlPAG may regulate the pain process in downward synaptic interactions. Nitric oxide is involved in the dH and dlPAG in morphine-induced analgesia in the rat formalin test. Morphine has analgesic effects in both phases of the rat formalin test. The morphine response is reduced in two stages by injection of the NO precursor L-arginine but not the nNOS inhibitor L-NAME in the dH and dlPAG. By injecting L-NAME before L-arginine in both nuclei, the morphine-induced response returns in the early stages. Due to the initial injection of L-NAME into dlPAG and the subsequent injection of L-arginine at dH, morphine analgesia is not reduced at all, indicating NO modulation in the pain pathway from dH to dlPAG.