Effect Of Nanoparticle Morphology Research Articles

Plasmon silica aerogel for improving high-temperature solar thermal conversion

The next generation concentrated solar thermal (CST) plants need to move toward higher operation temperatures to achieve higher thermodynamic efficiency. However, solar absorbers operating at high temperatures have a significant radiative thermal loss. In present study, a hybrid plasmon aerogel doped with ITO nanocylinders was proposed for improving the photothermal conversion in high-temperature CST plants. For the first time, the localized surface plasmon resonance was applied in high-temperature photothermal conversion to achieve the greenhouse effect of aerogel. The effects of nanoparticle morphology, size, and doping concentration on the infrared absorption performance of the hybrid aerogel were investigated by the combination of the T-matrix and Monte Carlo method. The operation temperature of the solar absorber was calculated to evaluate the insulation performance of the hybrid plasmon aerogels. The results show that, at the solar concentration ratio C = 20, the maximum increase of 113.9 °C in operation temperature can be achieved withaerogel thickness l = 5 mm and ITO nanocylinder doping concentration f v = 0.016%. This study sheds light on high-efficiency hybrid plasmon aerogel serving as a transparent thermal insulation barrier for high-temperature CST plants with high solar transmittance, low thermal conductivity, and low radiative thermal loss. • A kind of hybrid plasmon aerogel based on ITO nanocylinders and silica aerogel matrix is proposed and optimal designed for the CST plants. • The combination of T-matrix method and Monte Carlo method is applied to compute the radiative properties of the hybrid aerogel. • The operation temperature of solar absorber is calculated to assess the thermal insulating performance of the hybrid plasmon aerogel.

Pickering Emulsions Stabilized by Mesoporous Nanoparticles with Different Morphologies in Combination with DTAB.

The morphology of nanoparticles plays a significant role in the properties and applications of Pickering emulsions. Oil-in-water (O/W) Pickering emulsions were prepared using spherical, rod-like, and thread-like mesoporous silica nanoparticles (MSNPs) in combination with the cationic surfactant dodecyltrimethylammonium bromide (DTAB) as a stabilizer. The effects of nanoparticle morphology on the stability and stimuli-responsive properties of Pickering emulsions were investigated. For spherical and rod-like MSNP systems, stable Pickering emulsions were obtained at DTAB concentrations above 0.2 mmol·L–1. Stable Pickering emulsions containing thread-like MSNPs were produced at lower DTAB concentrations of approximately 0.1 mmol·L–1. The droplets with thread-like MSNPs were extremely large with an average diameter around 700 μm at DTAB concentrations of 0.1–0.3 mmol·L–1, which were approximately 20 times larger than those of conventional droplets. Scanning electron microscopy (SEM) images showed that all three types of MSNPs were located at the O/W interfaces. Irrespective of the morphology of the MSNPs, all the stable Pickering emulsions retained their original appearance for more than 6 months. By adding NaOH and HCl alternatively, the Pickering emulsions containing spherical and rod-like MSNPs could be switched between unstable and stable states more than 60 times. The Pickering emulsions containing thread-like MSNPs, by contrast, could have their droplet size switched between large and small more than 10 times without any obvious phase separation. The high anisotropy of thread-like MSNPs contributed to the low interface curvature of the droplets. This study revealed the relationship between the morphology of MSNPs and the characteristics of Pickering emulsions. These results enrich our knowledge about the formulation of Pickering emulsions and expand their applications.

Morphologies dependence of hydrogen evolution over CeO2 via ultrasonic triggering

Ultrasonic field can lead to cavitation bubbles explosion, which rises a high-frequency oscillation and generates a high-frequency current in semiconductor nanoparticles in suspension. However, the effect of nanoparticle morphology on ultrasonic-triggered H2 production is still unclear. To this end, herein, nanorods CeO2 (nrCeO2), CeO2 nanocubes (ncCeO2), and CeO2 nanospheres (nsCeO2) were successfully synthesized. Among them, one-dimensional nrCeO2 had the most abundant O-vacancies. As revealed by the COMSOL simulation, nanoparticle deformation was easier in nanorods compared with nanocubes and nanospheres, resulting in more efficient charge separation and facilitating H2 production reaction in nrCeO2. In detail, within a 5 h’ period, nrCeO2 presented the highest H2 production activity of 983.1 μmol g−1 h−1 with the positive charge (q+) trapping agent of CH3OH, and that of 278.1 μmol g−1 h−1 in pure water. This work presents a new understanding about the relationship between nanoparticle morphology and H2 production activity, and provides a promising, efficient, and clean H2 production approach, which can be further extended to multi-field coupling reactor.

Silver-chitosan and gold-chitosan substrates for surface-enhanced Raman spectroscopy (SERS): Effect of nanoparticle morphology on SERS performance

The search for cost-effective methods for the fabrication of sensitive and selective surface-enhanced Raman spectroscopy (SERS) substrates has led to recent studies exploring the incorporation of biopolymers as the supporting scaffold or nanostructure stabilizer. In this paper, we report on the effect of the enhancing nanostructure morphology on the SERS performance of chitosan-containing substrates. For this work, silver nanospheres, silver nanocubes, gold nanospheres, and gold nanorods were synthesized and fully characterized; then, SERS substrates were prepared using all of the morphologies and chitosan with varying concentrations and molecular weight to also test the effect of the biopolymer on the SERS effect. This work showed that the chitosan film allows for trapping of analyte molecules and thus, higher Raman intensities. It was found that the chitosan concentration plays an important role in this effect. The fabricated substrates showed minimum values of detected concentration between 10−4 and 10−9 M using p-ATP as probe molecule, depending on the nanostructure morphology used, showing that the silver nanocubes lead to a higher sensitivity and Raman intensities enhancement compared to the other dispersions studied.

An Experimental Study on the Effect of Particle Morphology, Temperature and Mass Fraction on the Density of Biomass-based Green Nanofluid

A novel class of fluids called nanofluids have been used for several applications among which is applications relating to heat transfer. Studying the thermo-physical properties of nanofluids will go a long way in designing nanofluids that will suit the desired application. In light of this, the present study presents the results obtained from the measurement of density from coconut fibre (CF) nanosphere-based nanofluids and CF nanotube-based nanofluids which were obtained from the dispersion of CF nanospere and CF nanotubes in 60:40 ethylene glycol/water (EG/W) in a ratio of 1:3.5. The temperature range was 15 o C to 60 o C at 15 o C intervals. The results obtained show a decrease in nanofluid density as temperature increased. On the other hand, the effect of nanoparticle morphology on the density of the nanofluids indicate that the nanofluids that contained CF nanotube had a higher density compared to the nanofluid containg CF nanosphere. A maximum density of 27.3% and 26.4% has been observed for CF nanotube-based nanofluid and CF nanosphere-based nanofluid respectively.

The effect of nanoparticle morphology in the filtration efficiency and saturation of a silicon beads fluidized bed

AbstractPolysilicon is a key commodity required for both electronics and solar photovoltaic modules. The traditional route to produce polysilicon involves the Siemens reactor, an energy intensive batch process. A more efficient, but more complex alternative process is the fluidized bed reactor (FBR). In an FBR silane is pyrolysed producing chemical vapor deposition (CVD) and aerosols. Efficient FBR operation requires yield optimization together with continuous and stable operation of the reactor. Such optimization is not straightforward because the aerosol formation mechanisms and incorporation into the FBR beads are not completely understood. In this work, two model aerosols with different morphology were tested and their filtration efficiency between 20 and 800 nm was determined. Bead saturation at different times was determined for each morphology and the scavenging factor over time for each case is reported. Such information can be of interest for establishing bed recirculation needs in a silicon FBR.

The effect of nanoparticle morphology on heat transfer and entropy generation of supported nanofluids in a heat sink solar collector

The thermal conductivity enhancement of nanofluids can be attributed to several factors such as volume fraction, temperature, material type, size and shape. In this study the effects of different morphology of supported nanoparticles, including copper (Cu), silver (Ag), aluminum dioxide (Al2O3), boehmite alumina (γ-AlOOH), molybdenum disulfide (MoS2) and silicon dioxide (SiO2), on heat transfer and entropy generation have been investigated in compression with each other in case of a water-based heat-sink solar collector located in Isfahan city, Iran. The control volume approach was used to solve the system of classical single phase three-dimensional governing equations by using the finite volume method (FVM). The standard k–ε turbulence model with enhanced wall function was selected. Furthermore, the spectral radiative transfer equation (RTE) was used to consider radiative heat transfer effects. Based on obtained results, the maximum value of averaged Nusselt number is achieved for MoS2 nanoparticles with sphere shape in φ = 4%, and it is followed by Ag with sphere shape in φ = 0.15%, Cu with sphere shape in φ = 0.20%, γ-AlOOH with sphere shape in φ = 4%, Al2O3 with sphere shape in φ = 4% and SiO2 with sphere shape in φ = 4%. The maximum value of outlet temperature is achieved for Ag nanoparticles with sphere shape in φ = 0.15%, and it is followed by Cu with sphere shape in φ = 0.20%, MoS2 with sphere shape in φ = 4%, Al2O3 with sphere shape in φ = 4%, SiO2 with sphere shape in φ = 4% and γ-AlOOH with sphere shape in φ = 4%. The minimum value of entropy generation is achieved for γ-AlOOH nanoparticles with bricks shape in φ = 2%, and it is followed by SiO2 with bricks shape in φ = 1%, MoS2 with bricks shape in φ = 1%, Ag with sphere shape in φ = 0.05%, Cu with sphere shape in φ = 0.05% and Al2O3 with bricks shape in φ = 1%. In case of heat transfer for all studied nanoparticles (metal and nonmetal nanoparticles), sphere shape is the best morphology for each nanoparticle material. For metal nanoparticles the minimum value of entropy generation is achieved by sphere shape. But for nonmetal nanoparticles the minimum value of entropy generation is reached by bricks shape morphology. Due to fulfill a heat exchanger with more energy efficiency (1st law view point), usage of sphere nanoparticles with optimum size and volume fraction is suggested. In order to achieve a heat exchanger with less entropy generation (2nd law view point), usage of bricks shape nonmetal nanoparticles with optimum size and volume fraction and sphere shape metal nanoparticles with optimum size and volume fraction is suggested.

Giant Pickering Droplets: Effect of Nanoparticle Size and Morphology on Stability.

The interaction between a pair of millimeter-sized nanoparticle-stabilized n-dodecane droplets was analyzed using a high-speed video camera. The droplets were grown in the presence of either poly(glycerol monomethacrylate)-poly(benzyl methacrylate) (PGMA-PBzMA) diblock copolymer spheres or poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate)-poly(benzyl methacrylate) (PGMA-PHPMA-PBzMA) triblock copolymer worms prepared by polymerization-induced self-assembly. The effect of nanoparticle morphology on droplet coalescence was analyzed by comparing 22 nm spheres to highly anisotropic worms with a mean worm width of 26 nm and comparable particle contact angle. Both morphologies lowered the interfacial tension, providing direct evidence for nanoparticle adsorption at the oil-water interface. At 0.03 w/v % copolymer, an aging time of at least 90 s was required to stabilize the n-dodecane droplets in the presence of the worms, whereas no aging was required to produce stable droplets when using the spheres, suggesting faster diffusion of the latter to the surface of the oil droplets. The enhanced stability of the sphere-coated droplets is consistent with the higher capillary pressure in this system as the planar interfaces approach. However, the more strongly adsorbing worms ultimately also confer stability. At lower copolymer concentrations (≤0.01 w/v %), worm adsorption promoted droplet stability, whereas the spheres were unable to stabilize droplets even after longer aging times. The effect of mean sphere diameter on droplet stability was also assessed while maintaining an approximately constant particle contact angle. Small spheres of either 22 or 41 nm stabilized n-dodecane droplets, whereas larger spheres of either 60 or 91 nm were unable to prevent coalescence when the two droplets were brought into contact. These observations are consistent with the greater capillary pressure stabilizing the oil-water interfaces coated with the smaller spheres. Addition of an oil-soluble polymeric diisocyanate cross-linker to either the 60 or the 91 nm spheres produced highly stable colloidosomes, thus confirming adsorption of these nanoparticles.

Double-layer antireflection from silver nanoparticle integrated SiO2 layer on silicon wafer: effect of nanoparticle morphology and SiO2 film thickness

Optical properties of silver nanoparticles (Ag NPs) on SiO2 thin films of variable thickness, as a plasmonic double layer on a plain silicon wafer, are investigated for broadband antireflection. The light confinement into the silicon is found to be sensitive to the SiO2 film thickness of a few nanometers due to an evanescent character of the Ag NPs’ near-fields. The Ag NPs’ size anisotropy plays a pivotal role in incident light coupling due to the sub-wavelength spatial variation of near-fields at the interface, which leads to reflectance spectrum oscillation behavior in the nanoparticles’ surface plasmon resonance and off-resonance regions. With an optimized SiO2/Ag NP double layer, the average reflectance in the 300–1200 nm spectral range is reduced to 14% in comparison to 42% in bare silicon, with a flat minimum reflectance of 3.5% in the 725–1020 nm spectral region. Finite difference time domain calculations are performed for spatial variation of near-fields and their angular distribution of far-fields at different inhomogeneous interfaces (where near-fields exist). The total reflectance from various configurations is simulated theoretically by considering the experimentally optimized physical parameters of the plasmonic double layer to support the observations. To verify the role of SiO2 surface topology apart from the nanoparticle morphology in plasmon near-field coupling, thermally grown SiO2 films are investigated along with the sputtered SiO2 thin films.

Real-time tracking of the hierarchical structure of biodegradable poly(butylene succinate-co-terephthalate) nanocomposites with fibrous attapulgite nanoparticles

Clearly understanding the structural development of materials during their preparation and processing allows for the fabrication of materials with expected properties that can be tailored for specific applications. In this work, we first presented the generation of poly(butylene succinate-co-terephthalate) (PBST) nanocomposites by combining the polymerization of copolymer with the simultaneous incorporation of fibrous attapulgite (ATP) nanoparticles with good dispersion. The lamellar structure, crystallization behavior and mechanical properties of PBST nanocomposites can be regulated by tuning the content of nanoparticles. The effects of nanoparticle morphology on the structure and properties of PBST nanocomposites with fibrous ATP and spherical silica nanoparticles also were investigated. The question why ATP nanoparticles always bring about faster crystallization rate and larger elongation at break than those caused by silica nanoparticles was answered as well. Furthermore, a schematic for the evolution of the hierarchical structure of PBST nanocomposites at each level during cooling was proposed. It was found that the formation and development of the hierarchical structure of PBST nanocomposites were highly temperature-dependent, and their cumulative growth leads to the final crystalline and hierarchical state. Studies of nanoparticles themselves and detailed changes of polymer structure in various scales are opening pathways for engineering flexible composites that can exploit the advantages of both polymers and nanoparticles.

The effect of nanoparticle morphology on the specific heat of nanosalts

Enhancing the specific heat capacity of molten salts by nanoparticle dispersion has emerged as a means to reduce the capital costs of thermal storage for concentrating solar thermal power plants, enabling cheaper solar electricity. Although several studies have shown near 30% enhancement in the specific heat of nanosalts other studies have reported a decrease of similar magnitude. In order to explain discrepancies reported in the literature, this study investigates the influence of various nanoparticle morphologies and preparation methods on the specific heat of nanosalts, which has not been systematically explored. To date, the extent of initial dispersion and the dispersion stability have only been reported on an ad-hoc basis in the literature. In the present study surface chemistry and sonication energy are controlled independently during preparation. By controlling both of these factors, the change of specific heat in nanosalts, results of this study present achieving up to 18% enhancement in specific heat of nanosalts by preparing an optimal nanosalt with distinctive nanoparticles.

Effects of Nanoparticle Morphology and Acyl Chain Length on Spontaneous Lipid Transfer Rates.

We report on studies of lipid transfer rates between different morphology nanoparticles and lipids with different length acyl chains. The lipid transfer rate of dimyristoylphosphatidylcholine (di-C14, DMPC) in discoidal "bicelles" (0.156 h(-1)) is 2 orders of magnitude greater than that of DMPC vesicles (ULVs) (1.1 × 10(-3) h(-1)). For both bicellar and ULV morphologies, increasing the acyl chain length by two carbons [going from di-C14 DMPC to di-C16, dipalmitoylphosphatidylcholine (DPPC)] causes lipid transfer rates to decrease by more than 2 orders of magnitude. Results from small angle neutron scattering (SANS), differential scanning calorimetry (DSC), and fluorescence correlation spectroscopy (FCS) are in good agreement. The present studies highlight the importance of lipid dynamic processes taking place in different morphology biomimetic membranes.

Manipulation of nanoparticles of different shapes inside a scanning electron microscope

In this work polyhedron-like gold and sphere-like silver nanoparticles (NPs) were manipulated on an oxidized Si substrate to study the dependence of the static friction and the contact area on the particle geometry. Measurements were performed inside a scanning electron microscope (SEM) that was equipped with a high-precision XYZ-nanomanipulator. To register the occurring forces a quartz tuning fork (QTF) with a glued sharp probe was used. Contact areas and static friction forces were calculated by using different models and compared with the experimentally measured force. The effect of NP morphology on the nanoscale friction is discussed.

The Effect of Nanoparticle Morphology on the Measurement Accuracy of Mobility Particle Sizers

The influence of particle morphology on the accuracy of nanoparticle size distributions measured by the engine exhaust particle sizer spectrometer (EEPS, TSI Model 3090) was studied using the scanning mobility particle sizer (SMPS, TSI Model 3936) as a reference. The EEPS shows higher total number concentrations with the maximum relative difference up to 67 % and smaller number median mobility diameters for polydisperse silver nanoparticles generated in the laboratory. To provide a quantitative explanation of the difference, generated polydisperse nanoparticles were classified as monodisperse particles with the initial equivalent mobility diameter (d m1) and sintered in the second furnace at different temperatures (room temperature to 600 °C), to change their morphologies for the comparison tests. Without sintering (room temperature), results show that the measured mobility diameter (d m2) of the EEPS is smaller than that measured by the SMPS when d m1 is larger than 30 nm and the difference increases as d m1 is increased from 30 to 300 nm. But the difference decreases as the morphology of particles is changed from branched chain agglomerates to spheres for d m1 less than 80 nm and the sintering temperature higher than 200 °C. Theoretical analysis shows that the mean charge per agglomerates is more than that of spheres resulting in overestimation of the electrical mobility and underestimation of the d m2 by the EEPS.

Thermophysical Properties of Nanoparticle-Enhanced Ionic Liquids (NEILs) Heat-Transfer Fluids

An experimental investigation was completed on nanoparticle-enhanced ionic liquid (NEIL) heat-transfer fluids (HTFs) as an alternative to conventional organic-based HTFs. These nanoparticle-based HTFs have the potential to deliver higher thermal conductivity than the base fluid without a significant increase in viscosity at elevated temperatures. The effect of nanoparticle morphology and chemistry on thermophysical properties was examined. Whisker-shaped nanomaterials were found to have the largest thermal conductivity temperature dependence and were also less likely to agglomerate in the base fluid than spherical-shaped nanomaterials.

Hybrid Polymer/Zinc Oxide Photovoltaic Devices with Vertically Oriented ZnO Nanorods and an Amphiphilic Molecular Interface Layer

We report on the effect of nanoparticle morphology and interfacial modification on the performance of hybrid polymer/zinc oxide photovoltaic devices. We compare structures consisting of poly-3-hexylthiophene (P3HT) polymer in contact with three different types of ZnO layer: a flat ZnO backing layer alone; vertically aligned ZnO nanorods on a ZnO backing layer; and ZnO nanoparticles on a ZnO backing layer. We use scanning electron microscopy, steady state and transient absorption spectroscopies, and photovoltaic device measurements to study the morphology, charge separation, recombination behavior and device performance of the three types of structures. We find that charge recombination in the structures containing vertically aligned ZnO nanorods is remarkably slow, with a half-life of several milliseconds, over 2 orders of magnitude slower than that for randomly oriented ZnO nanoparticles. A photovoltaic device based on the nanorod structure that has been treated with an amphiphilic dye before deposition of the P3HT polymer yields a power conversion efficiency over four times greater than that for a similar device based on the nanoparticle structure. The best ZnO nanorod:P3HT device yields a short circuit current density of 2 mAcm(-2) under AM1.5 illumination (100 mW cm(-2)) and a peak external quantum efficiency over 14%, resulting in a power conversion efficiency of 0.20%.