Dispersion Of Oxide Nanoparticles Research Articles

Porous PEO-Silica Hybrid Solid Electrolyte for All-Solid-State Lithium Ion Batteries

Dry polymer electrolytes based on poly (ethylene oxide), PEO, and Li-salt complexes are one of the most cheapest, environmentally friendly and promising materials for developing safe, cheap and durable all-solid-state Li-ion batteries. The rigid structures that are interesting from the point of view of application in all-solid-state battery cells are characterized by low conductivity at ambient temperatures. Dispersion of oxide nanoparticles inside the PEO-matrix greatly improves the physicochemical properties of the complex due to the physical interaction between the grains and the polymer matrix. Unfortunately, such a great effect drops at high loading-content, mostly above 10 wt%, owing to agglomeration of the nanoparticles and the consequence Li-ion blocking effect. In our work, we have proposed a novel approach that leads to a porous composite electrolyte consisted of higher weight fraction of nanoporous silica than PEO polymer. Here, the polymer-salt complex is being entirely soaked inside the mesoporous silica matrix that offers the mechanical support for the electrolyte. To do this, the walls of silica pores are tailored in the controlled manner with low molecular weight PEO polymer chains. The studied system that contained 70 to 80 wt% of SiO2 showed high conductivity, excellent mechanical strength and wide electrochemical potential window. Textural and structural properties of the starting materials and the hybrid electrolytes will be presented. Furthermore, the electrochemical properties of the porous electrolytes will be discussed to demonstrate the feasibility of our materials as solid electrolytes in all-solid-state Li-ion battery cells.

RETRACTED ARTICLE: Atomic insight into hydration shells around facetted nanoparticles

Nanoparticles in solution interact with their surroundings via hydration shells. Although the structure of these shells is used to explain nanoscopic properties, experimental structural insight is still missing. Here we show how to access the hydration shell structures around colloidal nanoparticles in scattering experiments. For this, we synthesize variably functionalized magnetic iron oxide nanoparticle dispersions. Irrespective of the capping agent, we identify three distinct interatomic distances within 2.5 Å from the particle surface which belong to dissociatively and molecularly adsorbed water molecules, based on theoretical predictions. A weaker restructured hydration shell extends up to 15 Å. Our results show that the crystal structure dictates the hydration shell structure. Surprisingly, facets of 7 and 15 nm particles behave like planar surfaces. These findings bridge the large gap between spectroscopic studies on hydrogen bond networks and theoretical advances in solvation science.

The Influence of Nickel Oxide Nanoparticle Dispersion on the Thermo Stability of Lubricant Oil

The homogeneous and substantial dispersion of nanoparticles into base fluids is vital since the final properties of any nanolubricant are estimated by their quality of stability. This paper addresses the effect of NiO nanoparticles dispersion into SN500 lubricant oil and its nonisothermal thermo stability. The dispersion of NiO nanoparticles is achieved by ultrasonication method. The thermo stability is estimated by Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC). The result shows that the thermo stability of base fluid enhances up to 0.3[Formula: see text]wt.% particle concentration then it decreases due to agglomeration of dispersed nanoparticles. The findings recommend that 0.1[Formula: see text]wt.% and 0.3[Formula: see text]wt.% of NiO-nanolubricant can be used for the temperature-dependent applications up to 200∘C.

Experimental investigation of alumina oxide nanoparticles effects on the performance and emission characteristics of tamarind seed biodiesel fuelled diesel engine

Abstract The present experimental research work is focused on enhancing the performance, and emission characteristics of a novel biodiesel blend- a mix of diesel (80%) and tamarind seed oil (20%), represented as tamarind seed methyl ester (TSME 20) along with alumina oxide (Al2O3) nanoparticles dispersion. The alumina nano particles (Al2O3) are added to TSME 20 at various concentrations such as 30 ppm, 60 ppm, and 90 ppm and are uniformly dispersed in biodiesel blend with the help of a magnetic stirrer as well as an ultrasonicator. The prepared Al2O3 nanoparticles are synthesized and characterised by using Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) techniques. The immersed metallic nanoparticles in TSME 20 exhibit in enhanced brake thermal efficiency as well as significant reductions in hydrocarbon and carbon monoxide emissions. Hence, the alumina oxide doped TSME biodiesel could be a viable alternative solution to diesel that can effectively address global energy crisis and environmental issues.

Optimization of condition for Cerium Oxide Nanoparticles dispersion as radioprotective agent in deionized water

Introduction: Cerium oxide nanoparticles (CONPs) are used as radiation protection agent in the in-vivo and in-vitro studies. The distribution stability of nano-suspension is one of the important factors during the studies. The aim of this study is optimization of condition for CONPs dispersion with sodium dodecyl sulfate (SDS-anionic surfactant) and tween 20 (nonionic surfactant) in deionized water. Materials and Methods: CONPs were obseved under scanning electron microscopy (SEM), then the dimensions and structure were obtained. The chemical composition of nanoceria was determined using Energy Dispersive X-Ray spectroscopy (EDS) analysis. The UV-VIS absorption spectrum of nanoceria suspension in the presence of SDS and Tween 20 surfactants were recorded and maximum absorption wavelength was determined. The mean sustained concentration of nanoceria suspension with different weight percentages of SDS (0.05, 0.15, 0.25, 0.45 and 0.65 wt%) was determined using standard curve. To increase the stability of the suspension distribution, the sonication time with a constant weight percentage of SDS was increased and the mean concentration was determined and then it was compared with suspensions containing various weight percentages of SDS. Results: According to the SEM images taken in this study, the shape of nanoceria was spherical approximately. EDS analysis determined that the CONPs consisting of cerium with 97.9 wt% and oxide with 2.1 wt% with a high percentage of confidence. The dimensions of nanoparticles were determined 29.3 nm. The UV-VIS maximum absorption of nanoceria suspension was recorded at 318 nm. The wavelength of maximum absorption was changed at the presence of tween 20. So it was removed from the study. The mean sustained concentration of nanoceria suspension with 0.45 wt% of SDS had a significant increase than the presence of 0.05, 0.15, and 0.25 wt% of SDS (P-value = 0.001). With an increase in the SDS weight percentage to 0.65%, a reverse effect was observed in the nano-suspension distribution. An increase of 5 hours of sonication time resulted in a significant increase in the mean sustained concentration of nanoceria suspension (P-value = 0.000). Conclusion: An anionic surfactant SDS with an optimum weight percentage of 0.45wt% can be used to increase the stability of the nanoceria distribution. Also, increasing the sonication time for 5 hours can be a better alternative than increasing the weight percentage of anionic surfactant SDS to achieve a stable distribution.

Solvent molecule mobilities in propylene carbonate-based electrolyte solutions coexisting with fumed oxide nanoparticles

Non-aqueous LiClO4 solutions kneaded with various fumed oxides (fumed silica, fumed alumina, and fumed titania) were employed as model systems of lithium ion batteries. The properties of the solid phase and Li+ ions, which affect solvent molecules, were evaluated using 1H NMR spectroscopy and 1H NMR relaxation time (T1, T2) measurements. The 1H NMR signals of propylene carbonate (PC) molecules were influenced by the coexisting solid phase in the LiClO4-PC solution/fumed oxide nanoparticle dispersion. The mobilities of the PC molecules drastically decreased in the presence of only 1–2 vol% of the solid phase (liquid phase thickness is 15–20 nm or less), regardless of the fumed oxide employed. In the IR spectra of the PC/fumed alumina systems, the vibrations at higher wavenumbers were predominantly observed because of indirect electron-donation from the solid surface. The 1H NMR signal detection ratios depended on the fraction of the liquid phase influenced by the solid phase. In the LiClO4-PC solution/fumed alumina systems, the 1H NMR signal detection ratios greatly decreased because of this influence; here, the large positive zeta potential of the solid phase surface of fumed alumina attracted the PC molecules, which had local negative electric fields owing to polarization. Moreover, the T1 and T2 results confirmed that the interaction between the solid phase and PC molecules is much smaller than that between the solid phase and water molecules. Additionally, it was seen that the PC solution system was more significantly affected than the aqueous solution system; the network structure of the entire PC solvent is greatly affected by the addition of the Li+ ion, and the relaxation time decreased significantly.

Study of active surface centers of Pt/CeO2 catalysts prepared using radio-frequency plasma sputtering technique

RF-plasma deposition of Pt on a nanosized ceria powder support has been performed directly in photoelectron spectrometer chambers to prepare model catalysts. The plasma deposition in an oxidizing environment results in the formation of highly dispersed oxide nanoparticles up to 2 nm large, which contain platinum solely as Pt4+ ions revealed by Eb(Pf4f7/2) = 74.6 eV. Thus prepared model catalyst samples arranged as (sub-monolayer) films of PtO2 nanoparticles on the surface of CeO2 are characterized by an increased thermal stability compared with PtO2 nanoparticles deposited on more inert supports. These PtO2/CeO2 model catalysts show a high activity in the CO oxidation even at room temperature. A detailed analysis of the O1s spectra obtained during the titration by CO of PtO2/CeO2 films strongly suggests that the reactive oxygen species are manifested with Eb(O1s) = 530.8 eV and 532.9 eV. The latter core level energies are attributed to oxygen in the platinum dioxide and to peroxide-like oxygen, presumably located at the interface between PtO2 and CeO2 particles. Results of our density-functional calculations indicate that the peroxide-like species can be energetically stabilized at the PtOx–CeO2 interfaces.

Photoluminescence and electrical conductivity measurement of liquid crystal doped with ZnO nanoparticles

ABSTRACTWe report the effect of dispersion of zinc oxide (ZnO) nanoparticles (NPs) on the conductivity, birefringence and fluorescence properties of commercially available room temperature nematic liquid crystal (LC) with the variation of dopant concentration. Significant changes have been observed in transition enthalpy, DC conductivity, photoluminescence and birefringence values of the LC material by the addition of ZnO NPs. While the inclusion of NPs enhances the electrical conductivity of the composite system, it results in a reduction in the birefringence value, which can be attributed to a decrease in the order parameter of the system due to the perturbed geometry of the LC. This also results in the increase in threshold voltage value, which has been speculated as due to the piezoelectric nature of the ZnO NPs. The analysis of the fluorescence spectrum indicates that ZnO NPs enhance the intensity in the LC phase along with a small blue shift.

Brønsted base mediated one-pot synthesis of catechol-ended amphiphilic polysarcosine-b-poly(N-butyl glycine) diblock copolypeptoids

Abstract Catechol moiety offers a versatile platform in the preparation of functionalized polymers, but it is not usually compatible with catalysis in polymerizations. To address these challenges, we suggest employment of one Brønsted base in masking the activity of catechol moiety and to modulate the polymerization. Based on this strategy, the ring-opening polymerization (ROP) of sarcosine N-carboxyanhydrides (Sar-NCA) was carried out using dopamine hydrochloride as an initiator and triethylamine as a Brønsted base. PSar with predicted molecular weights (M n,NMR=3.7 kg mol−1) and narrow dispersities (Đ<1.13) was prepared. Catechol initiator was successfully linked to PSar end as confirmed by MALDI-ToF MS. Subsequently, copolymerization of N-butyl glycine N-carboxyanhydrides (Bu-Gly-NCA) from the PSar in one-pot produced catechol end-functionalized amphiphilic polysarcosine-block-poly(N-butyl glycine) diblock copolypeptoids (cat-PSar-b-PGlyBu). Further, cat-PSar-b-PGlyBu enabled the aqueous dispersion of manganese oxide nanoparticles which was attributable to the anchor of the diblock copolymers onto the surface of the nanoparticles. The strategy for catechol masking and polymerization mediating by one Brønsted base offered a new avenue into the synthesis of catechol-ended block copolymers.

Hyperthermia Efficiency of Magnetic Nanoparticles in Dense Aggregates of Cerium Oxide/Iron Oxide Nanoparticles

Iron oxide nanoparticles are intended to be used in bio-applications for drug delivery associated with hyperthermia. However, their interactions with complex media often induces aggregation, and thus a detrimental decrease of their heating efficiency. We have investigated the role of iron oxide nanoparticles dispersion into dense aggregates composed with magnetic/non-magnetic nanoparticles and showed that, when iron oxide nanoparticles were well-distributed into the aggregates, the specific absorption rate reached 79% of the value measured for the well-dispersed case. This study should have a strong impact on the applications of magnetic nanoparticles into nanostructured materials for therapy or catalysis applications.

Silane-Capped ZnO Nanoparticles for Use as the Electron Transport Layer in Inverted Organic Solar Cells.

Zinc oxide (ZnO) nanoparticles are widely used as electron- transport layer (ETL) materials in organic solar cells and are considered to be the candidate with the most potential for ETLs in roll-to-roll (R2R)-printed photovoltaics. However, the tendency of the nanoparticles to aggregate reduces the stability of the metal oxide inks and creates many surface defects, which is a major barrier to its printing application. With the aim of improving the stability of metal oxide nanoparticle dispersions and suppressing the formation of surface defects, we prepared 3-aminopropyltrimethoxysilane (APTMS)-capped ZnO (ZnO@APTMS) nanoparticles through surface ligand exchange. The ZnO@APTMS nanoparticles exhibited excellent dispersibility in ethanol, an environmentally friendly solvent, and remained stable in air for at least one year without any aggregation. The capping of the ZnO nanoparticles with APTMS also reduced the number of surface-adsorbed oxygen defects, improved the charge transfer efficiency, and suppressed the light-soaking effect. The thickness of the ZnO@APTMS ETL could reach 100 nm without an obvious decrease in the performance. Large-area APTMS-modified ZnO films were successfully fabricated through roll-to-roll microgravure printing and exhibited good performance in flexible organic solar cells. This work demonstrated the distinct advantages of this ZnO@APTMS ETL as a potential buffer layer for printed organic electronics.

Conservation of acidic papers using a dispersion of oleic acid-modified MgO nanoparticles in a non-polar solvent

Abstract In this study, a new method was developed for the deacidification of acidic papers, by using a deacidifying dispersion of oleic acid-modified magnesium oxide (MgO) nanoparticles in cyclohexane. We reported that oleic acid-modified MgO nanoparticles were prepared by using a surface modification method. The results showed that the carboxylic group of oleic acid could react with the hydroxyl group on the surface of nanoparticles and the reaction was esterification. MgO nanoparticles were transformed from hydrophilic to lipophilic, with well dispersibility in cyclohexane for 6 h. Pure MgO nanoparticles all sank in cyclohexane after 30 s, so the deacidifying agents of pure MgO nanoparticles in cyclohexane could not be prepared for the deacidification of papers. The stable dispersion of oleic acid-modified MgO nanoparticles in cyclohexane then was used for the deacidification of papers. The accelerated aging tests were also used to evaluate the effect of the new method. Results showed that the surface pH of all types of papers were alkaline after the deacidification treatment and tensile strength values of those remained stable after accelerated aging. The deacidification treatment had ignorable influence on the appearance of papers, as well as inks and pigments on the paper surface. As the use of hydrophobic oleic acid-modified MgO nanoparticles, hydrophobicity of papers changed from hydrophilic to hydrophobic.

Transparent Dispersions of Monodispersed ZnO Nanoparticles with Ultrahigh Content and Stability for Polymer Nanocomposite Film with Excellent Optical Properties

A novel route was proposed for the synthesis of transparent dispersions of monodispersed zinc oxide (ZnO) nanoparticles via a high-gravity reactive precipitation combined with “inorganic–organic successive layer coating” method. The as-prepared nanodispersion had a uniform particle size of about 4 nm, high stability of over 12 months, and still remained transparent at ultrahigh solid content of 60 wt %. Highly transparent polylactide (PLA)/ZnO and PLA/ZnO/cesium doped tungsten oxide CsxWO3 nanocomposite films were further fabricated by a simple solution mixing method. Because of the uniform dispersion of nanoparticles, PLA/ZnO films could maintain the same visible transmittance as pure PLA film even when ZnO content reached 60 parts per hundred of PLA resin by weight (phr). Furthermore, the films could shield almost 100% ultraviolet radiation at ZnO content of up to 5 phr, thereby realizing good antiaging property. Besides their excellent transparency and UV-shielding property, PLA/ZnO/CsxWO3 films could ...

Biological Effects of Freshly Prepared and 24-h Aqueous Dispersions of Copper and Copper Oxide Nanoparticles on E. coli Bacteria

Copper and copper oxide nanoparticles are promising candidates for the role of “new antibiotics.” However, characteristics of their effect on microorganisms, depending on the nature of the dispersion medium and the time of storage of suspensions, have not been thoroughly studied, which limits the possibilities of application in practice. A comparative evaluation of the effects of freshly prepared and 24-h suspensions of copper and copper oxide nanoparticles (100 nm in size) on E. coli bacteria using the bioluminescence test is carried out. Distilled water and saline are used as dispersion media; the nanoparticle concentration is 1–0.0001 g/L. Significant differences in the antibacterial properties of freshly prepared suspensions of copper and copper oxide nanoparticles are revealed. Colloidal solutions of copper oxide in all studied concentrations have a significant toxic effect in both types of dispersion media (the survival rate of bacteria is less than 20–40%). An antibacterial effect is observed only at 1 g/L of copper nanoparticles (survival is less than 50%) in fresh aqueous dispersions and at 0.01–1 g/L in solutions based on saline (survival rate is 15–75%); i.e., in this case, the role of the dispersion medium is essential. The storage of solutions for 24 h results in a significant decrease in the toxicity of the colloid systems of copper oxide nanoparticles both in water and saline, while the antibacterial effect of suspensions of copper nanoparticles remains almost the same, regardless of the medium type. These phenomena can be caused by changes in the stability of colloidal systems accompanied by the aggregation of nanoparticles. These results indicate the importance of taking into account the nature of the dispersion medium and the time of storage of suspensions of copper-based nanoparticles for their efficient use as antimicrobial agents.

Ferrofluid synthesis using oleic acid coated Fe3O4 nanoparticles dispersed in mineral oil for heat transfer applications

Ferrofluids are stable dispersion of iron oxide nanoparticles in a carrier fluid which find potential applications in heat transfer. Fe3O4 nanoparticles of mean size in the range of 5–10 nm were synthesized using conventional co-precipitation method. This work deals with the synthesis of ferrofluids using mineral oil as a carrier fluid and oleic acid coated Fe3O4 nanoparticles as dispersed phase. Morphology (shape and size) and crystallinity of the synthesized nanoparticle is captured using TEM and XRD. Oleic acid coating on nanoparticle is probed using FTIR for confirming the stability of ferrofluid. Thermal properties of mineral oil based ferrofluid with varying concentration of nanoparticles are evaluated in terms of thermal conductivity. It was found that the thermal conductivity of ferrofluid increases upto 2.5% (w/v) nanoparticle loading, where a maximum enhancement of ∼51% in thermal conductivity was recorded as compared to the base fluid.

A mechanistic study of stable dispersion of titanium oxide nanoparticles by humic acid

Stable dispersion of nanoparticles with environmentally-friendly materials is important for their various applications including environmental remediation. In this study, we systematically examined the mechanisms of stable dispersion of two types of TiO2 nanoparticles (TNPs) with anatase and rutile crystalline structures by naturally occurring dissolved organic matter (humic acid) at different pHs, including at, below and above the Point of Zero Charge (PZC). The results showed that stable dispersion of TNPs by humic acid (HA) at all pHs tested can only be achieved with the assistance of ultra-sonication. The dispersion of TNPs by HA differed at the three pHs tested. Generally, HA greatly decreased the hydrodynamic diameters of TNPs at a very low concentration. The dispersion of TNPs became relatively stable when the HA concentration exceeded 5 mg/L, indicating that this HA concentration is required for stable dispersion of TNPs. The mechanisms involved in dispersion of TNPs by HA included electrostatic repulsion, steric hindrance and hydrophobic interaction. Electrostatic repulsion was identified to be the dominant mechanism. The dispersion of TNPs was enhanced when HA was added before ultra-sonication to avoid the partly irreversible re-aggregation of TNPs after sonication. The crystalline phases and concentrations of TNPs were also found to influence their stable dispersion. The findings from this work enhance understanding of the combined effects of HA, pH, ultra-sonication and crystalline structures of TNPs on their stable dispersion. The mechanisms identified can improve applications of TNPs in environmental water pollution control.

Hexagonal-shaped aminosilane magnetite nanoparticles: Preparation, characterization and hybrid film deposition

Hexagonal amino-functionalized magnetite nanoparticles were successfully produced by two-step method: initially, bare Fe3O4 nanoparticles were obtained by partial oxidation of ferrous ions in alkaline conditions, followed by hydroxyl groups interchanging with (3-aminopropyl) triethoxysilane (APTES) moieties. The products were evaluated for possible water repellent applications. Hybrid ternary films were prepared by spray coating in a layer-by-layer configuration: the hybrid polymeric matrix first, followed by modified iron oxide nanoparticle dispersion, both mixed with the third component, pre-hydrolyzed/precondensed sol–gel solution of hexadecyltrimethoxy silane (HSi). The found results demonstrate the ability of the hexagonal amino-functionalized magnetite nanoparticles to self-assembly and generate hierarchical roughness.

Fully metal oxide charge selective layers for n-i-p perovskite solar cells employing nickel oxide nanoparticles

An alcohol based nickel oxide nanoparticle dispersion was prepared and used to deposit hole conductor medium for a polymeric substance free perovskite solar cell in mesoscopic n-i-p configuration. In contrast to conventional p-i-n configuration or inverted type perovskite solar cells, nickel oxide layer was spin coated directly on perovskite layer and the perovskite layer was sandwiched between two metal oxides, TiO2 and NiO, resulting in n-i-p configuration. High surface area nickel oxide nanoparticles were synthesized by precipitation and successfully dispersed in isopropanol with the aid of ball milling, which was confirmed to breakdown the aggregates and stabilize the dispersion without the assistance of a stabilizing agent. This strategy leads to deposition of nickel oxide nanoparticles on perovskite layer without damaging the underneath perovskite layer and inhibiting the charge transfer between individual nanoparticles, confirmed by scanning electron microscopy, photoluminescence quenching and J-V measurements. Ultraviolet photoelectron spectroscopy analysis showed excellent matching of the band alignment of nickel oxide layers with that of perovskite. An efficiency of 10.89% was achieved after optimizing the nickel oxide layer thickness and comparing with a hole conductor free device using J-V measurements and electrochemical impedance spectroscopy revealed that nickel oxide layer possesses excellent electron blocking ability and reduces the recombination rate, which also in turn stabilizes the power output and hysteresis of the cells. This strategy is believed to be applicable for other metal oxides employed in charge selective layers of perovskite and organic solar cells.

In situ synthesis of polyaniline/Sm-doped TiO2 nanocomposites: evaluation of structural, morphological, conductivity studies and gas sensing applications

Polyaniline (PANI)/samarium doped titanium dioxide (Sm-TiO2) nanocomposites were prepared through in situ polymerization of aniline with different contents of Sm-TiO2 nanoparticles. The structure and morphology of the nanocomposites were characterized by FT-IR, UV, XRD, HRTEM, SEM, DSC and TGA. The electrical performances of the nanocomposites were investigated by AC and DC conductivity measurements. The effect of nanoparticles on PANI with the carbon monoxide, ammonia and hydrogen sulphide gas sensing properties were also studied. The results from FTIR and UV show the interaction of nanoparticles with PANI. The XRD study revealed the systematic arrangement of nanoparticles within the polymer matrix. HRTEM and SEM analysis showed the uniform structure of nanocomposites with spherically shaped dispersion of metal oxide nanoparticles. The result from DSC analysis indicated an increase in glass transition and melting temperature of nanocomposites than that of PANI. The higher thermal stability of the nanocomposite by the incorporation of nanoparticles was confirmed from TGA studies. The AC conductivity, dielectric constant and dielectric loss of composites were higher than pure PANI and the magnitude of these properties increased with the loading of nanoparticles. The DC conductivity indicates an increase in conductivity with increase in concentration of nanoparticles. The addition of metal oxide nanoparticles to PANI imparts excellent gas sensitivity to different gas at room temperature. Hence fabricated nanocomposites showed excellent thermal properties along with increased electrical conductivity and gas sensitivity, such type of nanocomposite can be used as a substitute for PANI in electrical or nanoelectronic devices.

Development of tensile-compressive asymmetry free magnesium based composite using TiO2nanoparticles dispersion

Abstract