Size Of Nanowires Research Articles

Model predicted optimization of experimental set-up and process conditions for microwave-assisted synthesis of silver nanowires

This work presents simulations led optimization of choice of a reactor for an experimental set-up for the continuous production of silver nanowires with certain constraints in terms of yield, reaction time, and dimensions of nanowires. The choice of reactors based on the simulations of reaction kinetics for nucleation and growth phases of driving the optimization of an experimental set-up and subsequent optimization of process conditions to maximize the yield of nanowires of desired dimensions. The optimized reactor configuration is dictated by the reaction kinetics and using a microwave in continuous mode becomes unavoidable. This makes the approach highly reproducible as well as scalable. The integration of conventional and microwave heating is simulated and subsequently optimized experimentally to attain a significant increase in nanowire yield under steady-state conditions with less than 15 min of residence time. The precise control over the rate in different reactor configurations governing nucleation, accelerated growth followed by slow growth to complete the conversion of precursor enables higher selectivity of nanowires with controllable dimensions resulting in 100 gm production per day using simple set-up. We systematically examined key reaction parameters, including the concentration of metal ions, residence time, and different reactor configurations. Our approach successfully yielded AgNWs with 40–60 nm diameter and 15 µm length. The cost associated with this process for synthesizing AgNWs is less than 10$ per gram. This study highlights the potential of continuous, high-throughput processes for controlling nanowire size and yield through advanced reactor engineering.

Morphologically tuned MnO2 thin film electrodes prepared by growth kinetic dependent SILAR approach for high-performance extrinsic pseudocapacitors

Rationally designed electrode materials that are morphologically tuned to attain large surface area can significantly possess the extrinsic pseudocapacitive charge-storing ability. Therefore, the current work approach focuses on synthesizing binder-free MnO2 thin film electrodes with tuned morphology by the SILAR method through alteration in growth kinetics. The growth kinetics of SILAR are controlled by altering the precursor concentrations ratio among metal precursor (MnCl2) and oxidizing agent (KMnO4). The structural analysis confirmed the preparation of the δ-MnO2 phase of manganese oxide. Moreover, alteration in growth kinetics resulted in a change in surface morphology with reduced nanowire size of marigold-like δ-MnO2 microflowers. The MO-3 thin film electrode prepared at an optimum KMnO4 and MnCl2 precursor concentration ratio of 2:1 provides the maximum extrinsic pseudocapacitive conduct with the maximum specific capacitance of 774.5 F g−1. Furthermore, the aqueous symmetric supercapacitor device exhibits the highest specific capacitance of 106 F g−1 with a specific energy of 14.8 Wh kg−1 at a high specific power of 1792 W kg−1 and exhibits 83.2 % capacitive retention over 10,000 cycles. Furthermore, the symmetric aqueous device (MO-3//Na2SO4//MO-3) lights 5 red LEDs, demonstrating its commercial viability for energy storage systems. This research facilitated the scalable synthesis of binder-free δ-MnO2 fine film electrodes with a desired morphology by facile SILAR method, ensuring their practical applicability in symmetric extrinsic pseudocapacitor devices.

Biochar assisted synthesis of α-MnO2 nanowires with superior performance for non-radical activation of peroxymonosulfate

Non-radical activation of peroxymonosulfate (PMS) is a promising water treatment technology for removing refractory organics, but its mechanism is still ambiguous and the development of highly efficient catalyst is still a challenge. Herein, α-MnO2 nanowires were synthesized by a hydrothermal method with the assistance of biochar and their performance for PMS activation was studied. The characterization results show that the addition of biochar had little effect on the crystal phase and valence state of MnO2 but significantly reduced the size of nanowires. These nanowires had mesoporous structure, high surface area and oxidation ability, resulting in their superior performance for removing organic pollutants with PMS activation. The degradation of phenol by α-MnO2-PMS followed first order kinetics with an activation energy of 14.82 kJ mol−1. Electron paramagnetic resonance and radical scavenging experiments demonstrated that this activation process followed the non-radical mechanism. The quenching effect of scavengers led to the misleading role of singlet oxygen. In fact, surface activated PMS (MnO2–PMS*) rather than singlet oxygen was the reactive species. Weak acidic condition was conducive for the formation of MnO2–PMS* complexes. This catalyst exhibited good reusability and high activity for removing various organic pollutants, and the common substances in real water had little effect on its performance, suggesting its potential application in wastewater treatment.

Ultra-thin size-controllable surface plasmon polariton laser by PDMS-assisted imprinting

Plasmonic laser has great potential to overcome the optical diffraction limit, playing a crucial role in advancing nanophotonics and nanoelectronics for on-chip integration. However, current plasmonic lasers face several challenges, such as the difficulty in controlling nanowire (NW) size, disordered arrangement, and complicated fabrication process. Herein, ultra-thin gain media for plasmonic lasers below the cutoff size of the photonic mode are prepared using the polydimethylsiloxane-assisted imprinting. This method enables precise control over the size of the perovskite NW, with the minimum size achievable being 60 nm. As a result, the plasmonic lasing is achieved from the CsPbBr3 NW-based device with a threshold as low as ∼49.13 μJ cm−2 and a Quality Factor (Q) of 1803 at room temperature, demonstrating its capability for achieving high-quality lasing. Meanwhile, a dual-pumping time-resolved fluorescence study suggests that the radiative recombination lifetime of CsPbBr3 NWs is shortened by a factor of 10 due to the Purcell effect, confirming the plasmonic effect exhibited by the device. Furthermore, a plasmonic laser array is developed using this method, demonstrating the applicability of the imprinting method in complex graphic fabrication. This breakthrough provides a solution for the application of plasmonic laser arrays in optoelectronic integration.

Improved antimicrobial activities of biphasic titania nanowires against Gram-negative and Gram-positive bacteria

This research focused on the synthesis of biphasic titania nanowires from commercially available anatase titania via hydrothermal method to improve its antimicrobial activity. The electron microscope scanning (SEM) showed that the titania nanowires structures were successfully synthesized with width varying from 17 to 96 nm and length from 0.7 to 8 μm. The titania nanowires have biphasic structure of brookite and anatase, as observed from the X-ray diffraction pattern. The band gap was calculated from the ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS) spectra at 3.3eV, which is between the range of pure anatase and pure brookite band gap. The crystallite size of the titania nanowires was calculated using the Scherer equation and showed a much smaller crystallite size compared to commercial titania. The antimicrobial activity of the titania nanowires was then investigated against gram-negative and gram-positive bacteria. They exhibited improved antimicrobial activity against the Gram-negative Pseudomonas aeruginosa and Escherichia coli along with Gram-positive Bacillus subtilis. Interestingly, their inhibition zone was comparable to the antibiotic tetracycline. Meanwhile, the commercial titania did not show any antimicrobial activity on any tested bacterial strains. The improved antimicrobial activity of the titania nanowires was attributed to its biphasic phase, small particle size, and its one-dimensional morphology.

Human Serum Albumin Mediated Controllable Synthesis of Defect-Rich Copper Hydroxide Nanowire for Cuproptosis-Based Anti-Tumor Therapy.

Cuproptosis, as a newly identified form of programmed cell death, shows great promise in cancer treatment. Efficient Cu+ delivery while avoiding systemic toxicity and elimination of the resistance from over-expressed intracellular copper chelator glutathione (GSH) are critical for cuproptosis. Herein, this work innovatively constructs a biocompatible and defect-rich copper hydroxide nanowire (HCu nanowire) through a human serum albumin (HSA) mediated biomineralization method. This work finds that the morphology and size of HCu nanowires can be controlled adjusted by the feed ratio of HSA and Cu2+. Remarkably, except for outstanding biocompatibility, HSA coordination endows HCu nanowires abundant oxygen vacancies (OVs), and the defect-rich HCu nanowire possesses excellent GSH consumption efficiency. Density functional theory studies indicate that OVs change GSH absorption energy on defective HCu nanowires. In cancer cells, HCu nanowires deplete GSH and simultaneously produce sufficient free Cu+ for enhanced cuproptosis. Meanwhile, Cu+ can catalyze endogenous H2O2 into hydroxyl radicals (·OH) via a Fenton-like reaction. Thus, synergetic cuproptosis and ROS mediated apoptosis against tumor are achieved. The experimental results show that HCu nanowires have a better performance in both antitumor efficiency and safety compared with chemotherapeutic drug Dox at the same dose, demonstrating its great potential in clinical applications.

Size-dependent optical and dielectric anisotropy of CdS nanowire doped high-birefringent nematic liquid crystalline compound

Highly birefringent liquid crystals have grabbed ample attention because of their potential applications as an active medium for devices in visible, infrared and other spectral regions. Here, we have attempted to study the effect of the size and concentration of CdS nanowires on a nematic liquid crystal. Anisotropy in liquid crystals is one of those distinguishing traits that gain their superiority over other materials. We hereby have analyzed how optical and dielectric anisotropy respond to variations in the size and concentration of the dopant. The study is of significant scientific value because there is very little literature available on how dopant size can alter liquid crystalline properties and also introduces a method to tune the properties of pure liquid crystals (LCs) by varying the size and concentration of the dopant. The study explains how the size of the nanowires changes the analyzed parameters and up to what extent. The obtained results yield a significant increase in both optical and dielectric anisotropy by doping CdS nanowires making them an excellent choice for dopant selection. CdS-doped nematic LC mixtures have proved to be highly birefringent and possess a high positive dielectric anisotropy as well. Such a compound can be of great application in device fabrications such as laser beam steerers, electronic lenses, attenuators and light shutters, etc.

Analysis of the effect of size, material, position and period of metal nanowires on the performance of thin film solar cells

Analysis of the effect of size, material, position and period of metal nanowires on the performance of thin film solar cells

Size control of InP nanowires by in situ annealing and its application to the formation of InAsP quantum dots

We carried out in situ annealing of InP nanowires (NWs) in a metal-organic vapor phase epitaxial (MOVPE) growth reactor to control and reduce the tip size of InP NWs. InP NWs were grown by selective-area (SA) MOVPE on partially masked (111)A InP substrates, and annealing was successively applied in tertiarybutylphosphine (TBP) ambient. Initially, the InP NWs had a hexagonal cross-section with {112¯} facets vertical to the substrates; they became tapered, and the edges were rounded by annealing. By appropriately selecting the annealing temperature and initial NW diameter, the tip size of the NW was reduced and NWs with a tip size of 20 nm were successfully formed. Subsequently, a thin InAsP layer was grown on the annealed NWs and their photoluminescence was investigated at low temperatures. The characterization results indicated the formation of InAsP quantum dots (QDs) emitting in the telecom band. Our approach is useful for reducing the size of the NWs and for the controlled formation of InAsP QDs embedded in InP NWs in photonic devices compatible with telecom bands.

Electrodeposition of 3D Au1-XAgx Nanowire Networks – Influence of Ag on the Electrochemical Properties

We present the synthesis of free-standing Au1-xAgx alloy nanowire networks with controlled geometry and atomic composition, by ion track nanotechnology and electrodeposition, and their electrochemical characterization.Polycarbonate polymer templates with interconnected nanochannels are fabricated by sequential irradiation from four directions with 1-2 GeV Au ions at the UNILAC accelerator of GSI, followed by selective chemical etching of the ion tracks. [1] Au1-xAgx alloy nanowires are subsequently synthesized by potentiostatic electrodeposition inside the channels. Nanowire growth rate and atomic composition are tuned by varying the deposition potential and the electrolyte composition. The technique provides precise control of the nanowire size, interconnectivity, and composition. [2,3,4] By dissolving the polymer template, free standing nanowire networks are obtained showing good mechanical stability. Geometry, crystallinity, and composition of the alloy Au1-xAgx nanowires were analysed by TEM, EDX, and XPS. The results demonstrate that the Ag molar fraction can be precisely adjusted between 10% and 90%.The electrochemically active surface area was determined by measuring the double layer capacitance of the nanowire network surface, and is in good agreement with the calculated theoretical surface area. The 3D network exhibit surface areas up to 200 times larger than their planar counterpart, which makes them highly interesting for catalytic processes. Their electrochemical activity in alkaline solution is investigated by cyclic voltammetry in 0.1 M KOH electrolyte, and will be discussed in this presentation.[1] M.E. Toimil-Molares, Beilstein Journal of Nanotechnology, 3.1, 860-883 (2012).[2] M. Rauber, I. Alber, S. Müller et al. Nano Letters, 11.6, 2304-2310 (2011).[3] L. Burr, I. Schubert, W. Sigle et al. The Journal of Physical Chemistry C, 119.36, 20949-20956 (2015).[4] M. Li, N. Ulrich, I. Schubert et al. RSC Advances, 13, 4721-4728 (2023).

Influence of vacuum annealing on mechanical characteristics of focused ion beam fabricated silicon nanowires

This paper describes the influence of vacuum annealing on the mechanical characteristics of silicon (Si) nanowires (NWs) fabricated using focused ion beam (FIB) technologies. Two types of Si NWs having a cross-sectional one-side length or diameter ranging from 19 to 447 nm are prepared using the direct milling and Ga ion doping functions of FIB. The Si NWs prepared are annealed at 400–700 °C in high vacuum for 10 min, followed by quasi-static uniaxial tensile testing using a microelectromechanical system based tensile test system in a scanning electron microscope. All the Si NWs fracture in a brittle manner. Young's modulus of submicrometer-sized Si NWs shows both annealing and specimen size influences in the range from 120 to 170 GPa, whereas that of nano-sized Si NWs shows only annealing influence in the range from 60 to 110 GPa. Tensile strength scatters greatly, ranging from 1.0 to 7.2 GPa, which increases with increasing the NW size. A transmission electron microscope and an atomic force microscope suggest that, by annealing, recrystallization happens in the damaged layer introduced by FIB milling and the NW surface morphology changes due to its recrystallization and gallium (Ga) ion evaporation. Fracture origin is discussed through the comparison between surface roughness and crack length estimated by the Griffith theory of brittle fracture.

Top-down fabrication of Ge nanowire arrays by nanoimprint lithography and hole gas accumulation in Ge/Si core–shell nanowires

Germanium (Ge) nanowire arrays are expected to be a promising channel material for high-performance field-effect transistors (FETs) due to their excellent electronic transport properties, silicon (Si) compatibility, and high integration. To produce highly ordered Ge nanowires with low contamination, nanoimprint lithography (NIL) and Bosch etching are used and the size of nanowires is reduced from 220 nm to ∼30 nm by adjusting the H2O2 etching time. Furthermore, Ge/Si core–shell nanowires are prepared by forming p-Si shells on Ge nanowires, and their good crystalline quality and sharp interfaces are confirmed by transmission electron microscope (TEM) observations. This structure is used as a high-mobility channel in HEMT-type devices, and the accumulation of hole gas inside the Ge nanowires, which is the most important, is demonstrated and investigated by Raman scattering.

Microscopic Characteristics of Kinking Phenomenon in Vertically Free-Standing Nanowires

Vertically free-standing nanowires, synthesized through vapor-based growth, can undergo changes in their growth directions known as kinking. These alterations can significantly influence the physical and chemical properties of nanowires, thereby expanding their potential applications. The occurrence of kinks is commonly associated with variations in vapor, temperature, seed, and/or their combinations. However, the interplay among different growth factors complicates the identification of the dominating factor and, consequently, limits precise control over nanowire morphology. Theoretical models, incorporating factors like supersaturation, wetting angle, nanowire size, and surface/interface energies tied to growth conditions, have been developed to describe and predict kinking during nanowire growth. While a few pivotal parameters, such as surface/interface energies and wetting angles, can be subtly adjusted through minor alterations in growth conditions, accurately predicting the occurrence of kinks remains a practical challenge. Conversely, in the present review, we attempted to elucidate connections between microscopic aspects, such as changes in composition and the formation of defects, and the nucleation and progression of kinks. This effort aims to construct a predictive framework that enhances our understanding of the tendencies in nanowire growth.

Wide refractive index detection range sensors based on D-shape photonic crystal fiber with a nanoscale gold wire

Optical sensing based on photonic crystal fiber (PCF) is attracting interests. Currently, PCF sensing suffered from the insensitivity with the changes of environmental surroundings with low refractive index. A D-shape PCF supporting plasmonic resonances based on gold nanowires is designed to demonstrated the sensitivity optical sensing in the refractive index range from 1.00 to 1.30. The finite element method is performed to optimize the device parameters, including the diameter of the large and tiny air holes, the size of the gold nanowire, and the space between the air holes. Utilizing plasmon-induced confined electrical around gold nanowires, the predicted device performance in spectral and amplitude sensitivities are up to 19,400 nm/RIU and 5.15 × 10−6 RIU, respectively. It is believed that the designed sensor can promote the development of applications in biological and pharmaceutical.

Size and kink effects on thermal conductivity in nickel nanowires

The potential applications of nanowires in thermal management and thermoelectric energy conversion have sparked extensive research on thermal transport in various nanowires. Nickel nanowires, with their unique properties and promising applications, have been extensively studied. However, the influence of size, particularly the impact of kink structures, on the thermal transport behavior in nickel nanowires remains unclear. In this paper, we employed electron-beam lithography and liftoff techniques to fabricate suspended nickel nanowires with varying sizes and kinks to experimentally investigate the size and kink effect on the thermal conductivity. The experimental results revealed that the thermal transport behavior of nickel nanowires is significantly influenced by both size and kink effects. Notably, as the nanowire size decreases, the thermal conductivity also decreases. Furthermore, we discovered that the thermal conductivity can be adjusted by altering the number and angle of kinks. Increasing the number of kinks from 18 to 36 resulted in a significant decrease in thermal conductivity. In contrast, as the kink angle decreased from 157° to 90°, the thermal conductivity also decreased. However, intriguingly, when the kink angle was further decreased from 90° to 43°, the thermal conductivity increases. This non-monotonic change in thermal conductivity with the kink angle provides an interesting insight into the intricate behavior of heat carriers in kinked nickel nanowires. Additionally, we found that varying the alloy elements can profoundly alter the thermal conductivity of nanowires with kinks. These results offer valuable insights into the behaviors of heat carriers, including electrons and phonons, during heat transfer in nickel nanowires.

Novel physical sunscreen from one-dimensional TiO[formula omitted] nanowire: Synthesis, characterization and the effects of morphologies and particle size for use as a physical sunscreen

The performance of the one-dimensional (1D) morphology as an inorganic UV filter for sunscreens of titanium dioxide (TiO2) was evaluated in this research. The 1D TiO2 nanowires were prepared using solid TiO2 and 10 M NaOH as precursors via a modified hydrothermal method, followed by calcination at 400–900°C for 5 h. The influences of TiO2 loading, hydrothermal time and calcination temperature were studied on the morphologies of the as-prepared samples. The morphologies of the TiO2 nanowires were investigated using SEM and TEM techniques. The results found all the variables directly affected the particle size and shape of the TiO2 nanowires. The hydrothermal synthesis conditions using a TiO2 loading of 0.2 g at 220°C for 24 h (HTiO2) resulted in a particle size that was the longest and narrowest in length and diameter, respectively. The first product from the hydrothermal synthesis is H2Ti3O7, which can transform into TiO2(B) (TiO2@400), anatase (TiO2@700) and rutile (TiO2@900) by calcination at 400, 700 and 900 °C, respectively. The calcined samples were selected for a porcine skin penetration study. The 1D morphology particles were localized on the stratum corneum of the skin, while the comparison spherical particle penetrated the deeper layer. From the SPF test, the highest SPF is TiO2 anatase.

Effects of Field Strength and Silver Nanowire Size on Plasmon-Enhanced N2 Dissociation.

Dissociation of the nitrogen molecule via plasmon-enhanced catalysis using noble metal nanoparticles has been investigated both experimentally and computationally in recent years. However, the mechanism of plasmon-enhanced nitrogen dissociation is still not very clear. In this work, we apply theoretical approaches to examine the dissociation of a nitrogen molecule on atomically thin Agn nanowires (n = 6, 8, 10, 12) and a Ag19+ nanorod. Ehrenfest dynamics provides information about the motion of nuclei during the dynamics process and real-time TDDFT calculations show the electronic transitions and population of electrons over the first 10 s of fs time scale. The activation and dissociation of nitrogen are typically enhanced when the electric field strength increases. However, the enhancement is not always monotonic with field strength. As the length of the Ag wire increases, nitrogen is typically easier to dissociate and thus requires lower field strengths, even though the plasmon frequency is lower. The Ag19+ nanorod leads to faster dissociation of N2 than the atomically thin nanowires. Overall, our detailed study yields insights into the mechanisms involved in plasmon-enhanced N2 dissociation, as well as provides information about factors that can be used to improve adsorbate activation.

Study on the Preparation and Performance of Low-Temperature Sintering and High-Thermal-Conductivity Silver Nanowire Film

This paper proposes a new silver nanoscale joining material, silver nanowire film, as an alternative joining approach for high-power and large-size chip packaging. The silver nanowire film was prepared by pressing filtration with silver nanowire that was synthesized using the polyol method. We found that the tensile strength of the film reached 3.40 MPa and the content of the silver reached up to 99.0 wt%. This paper further studies the influence of the size of silver nanowires on the performance of silver nanowire film. The experimental results show that the silver nanowire films prepared with silver nanowires with longer lengths and smaller diameters displayed better performances. The silver nanowire film with the best performance was prepared using silver nanowire with a diameter of 88 nm and a length of 29 μm. The thermal resistance of the sintered silver nanowire film that was hot-pressed at 250 °C 10 MPa was only 1.28 K∙W−1. The shear strength of the sintered joint was 56.4 MPa, and the fracture that occurred in the sintered silver nanowire film displayed a good plasticity.

Evolutionary Plasmonic Properties of Single Truncated Ag Nanowire-on-Au Film Nanocavity

Noble metal nanocavities have been widely demonstrated to possess great potential applications in nano-optics and nanophotonics due to their extraordinary localized surface plasmon resonance. However, most metal nanocrystals synthesized by chemical methods often suffer from truncation with different degrees due to oxidation and dissolution of metal atoms at corner and edges. We investigate the influence of shape truncation on the plasmonic properties of single Ag nanowire on Au film nanocavity using the finite difference time domain method. When the Ag nanowire (the circumradius R 2 = 50 nm) is gradually truncated from pentagonal to circular geometry, the scattering peak position of the nanocavity shows prominent blue shift from 962 nm to 608 nm, suggesting a nonnegligible role of truncation on plasmonic properties. The electric field strength and charge distribution of the structure reveal the evolution from dipole mode to quadrupole mode. It is also found that the plasmon resonance wavelength is linearly dependent on the truncation ratio R 1/R 2 (R 1 is the inradius) and the modulation slope is also reliable to the size of Ag nanowire. Our observations could shed light on developing high-performance tunable optical nano-devices in future.

Effect of oxidation on mechanical properties of copper nanowire: A ReaxFF (reactive force field) molecular dynamics study

Nanostructures with high surface area to volume ratio, such as oxidized and coated Cu nanowires (NWs), exhibit unique mechanical properties due to their size and surface effects. Understanding the complex oxidation process of Cu NWs at nanoscale and quantifying its resulting effects on mechanical behavior and properties are significantly essential for effective usage of Cu NW devices in a wide range of applications in nanoelectronics. Here, we perform molecular dynamics simulations using ReaxFF (reactive force field) to investigate the oxidation process and mechanisms of [001]-oriented cylindrical Cu NWs and its contribution on the mechanical deformation behavior and material properties as a function of NW sizes. The relatively thin oxide CuxOy layer is formed on the surface of Cu NWs in an O2 environment, creating a core/shell (Cu/CuxOy) NW structure that played a key role in governing the overall tensile mechanical deformation behavior and properties of Cu NW. The formation of oxide layer effects, including the resulting interface and defects, leads to a reduction in the initial dislocation nucleation barrier, which facilitates the onset of plasticity and stress relaxation, ultimately resulting in a negative impact on the tensile strength, Young's modulus, yield stress and strain, and flow stress when compared to pristine counterparts. It is worth noting that the tensile mechanical response and properties of the Cu NWs are highly dependent on the pre-existing oxide shell layer associated with the size of NW, determining the overall mechanical performance and properties of Cu NWs.