Ethanol Dispersion Research Articles

Influence of Charge Transport Layers on Open-Circuit Voltage and Hysteresis in Perovskite Solar Cells

Summary Perovskite materials have experienced an impressive improvement in photovoltaic performance due to their unique combination of optoelectronic properties. Their remarkable progression, facilitated by the use of different device architectures, compositional engineering, and processing methodologies, contrasts with the lack of understanding of the materials properties and interface phenomena. Here we directly target the interplay between the charge-transporting layers (CTLs) and open-circuit potential ( V OC ) in the operation mechanism of the state-of-the-art CH 3 NH 3 PbI 3 solar cells. Our results suggest that the V OC is controlled by the splitting of quasi-Fermi levels and recombination inside the perovskite, rather than being governed by any internal electric field established by the difference in the CTL work functions. In addition, we provide novel insights into the hysteretic origin in perovskite solar cells, identifying the nature of the contacts as a critical factor in defining the charge accumulation at its interface, leading to either ionic, electronic, or mixed ionic-electronic accumulation.

Mass-Producible Organic Nanocapsule with Water-Responsive Releasing Ability

An organic nanocapsule was obtained by mixing zinc acetate powder into a peptide lipid dispersion in ethanol. The nanocapsule was mass-produced at a scale of over 100 g L–1 within 1 h. Fourier transform infrared spectroscopy and scanning electron microscopy revealed that a zinc-peptide lipid complex was formed within 15 min, which subsequently transformed into a nanocapsule as a result of changes in the hydrogen bonding networks between the peptides. A variety of organic dyes could be encapsulated by simply adding them during the nanocapsule formation. We also confirmed their high stabilities in organic solvents, water-responsive morphological change, and resulting guest release. The water-responsive nanocapsule is expected to be useful in a variety of fields.

27Al, 63Cu NMR spectroscopy and electrical transport in Heusler Cu–Mn–Al alloy powders

The ultrafine powder of the Heusler Cu-13,1Mn-12,6Al (wt.%) alloy produced by electrical spark dispersion (ESD) in ethanol and the pellets prepared by pressing of the powders and aged in various gas environment (air, Ar, vacuum) were studied by XRD, nuclear magnetic resonance, magnetic and electric transport methods. The constituent phases were identified as b.c.c. α–Cu–Mn–Al, f.c.c. γ-Cu–Mn–Al, Cu2MnAl, and oxides. The sizes of the coherently scattering domains (CSD) and the saturation magnetizations were in the range of 4–90 nm and 0–1.5 Am2/kg, respectively. 27Al and 63Cu NMR spectra of the powders and pellets have shown hyperfine structure caused by contributions from atomic nuclei of the constituent phases. The aging of pellets in different gas environments had effect on their phase composition but no effect on dispersion of the phases. In contrast to the as-cast alloy, electrical resistance of the pellets evidenced semiconducting behavior at elevated temperatures due to the presence of metal oxides formed on the surfaces of nanoparticles.

Graphene-catalyzed formation of C\u2261N bonds via cleavage of C-C and N-O bonds in ethanol and nitrate under room temperature

The cleavage of carbon-carbon bonds and the formation of carbon-nitrogen bonds play crucial roles in chemical synthesis. However, these reactions usually proceed at high temperature and involve multiple steps. Herein, we report an unusual and novel reaction catalyzed by graphene. The C-C bond in ethanol and the N-O bond in nitrate can be broken under room temperature, accompanied by the formation of the C≡N bond. We demonstrate these reactions and elucidate their mechanisms by verifying that the product is silver cyanide which was formed when mixing a solution of silver nitrate and ethanol with graphene dispersion in ethanol at room temperature. The pivotal reason for the reaction is the formation of the precipitated silver cyanide. In a broader context, this discovery opens a significant new path for the breakage of the C-C bond in ethanol and the synthesis of nitriles under mild conditions. Also, the graphene was first reported as a catalyst for the room-temperature reaction.

Soluble Graphene Nanosheets from Recycled Graphite of Spent Lithium Ion Batteries

Soluble graphene nanosheets are fabricated from recycled graphite of spent lithium ion batteries through a modified Hammers process followed by deoxygenation with NaOH–KOH eutectic. Ultrasonic exfoliation in N-methyl-pyrrolidone indicates the loosened graphene layers in recycled graphite are prone to exfoliation. Reduction of the exfoliated graphene oxide sheets was conducted in molten NaOH–KOH eutectic at different temperatures. The results show that molten NaOH–KOH effectively eliminates the unsaturated oxygen-containing moieties from the exfoliated graphene oxide sheets while creating more hydroxyl functional groups. Higher temperature treatment is more prone to remove hydroxyls while producing the shrinkage on the surface of graphene sheets. Graphene sheet with a good solubility is produced when the graphene oxide is heat-treated at 220 °C for 10 h. After reduction, the graphene oxide sheets exhibit excellent dispersibility or solubility in water, ethanol and other polar solvents, therefore being highly desirable for solution processing of graphene materials. Such study not only identifies a high-quality stockpile to prepare soluble graphene but also paves a feasible alternative of graphite recycling from spent lithium batteries.

In Situ FT-IR and DFT Study of the Synergistic Effects of Cerium Presence in the Framework and the Surface in NH3-SCR

Mn-Ce/CeAPSO-34 was prepared, in which manganese and cerium were supported on the surface through using the Ethanol dispersion method, while cerium was incorporated in the SAPO-34 framework by a one-step hydrothermal method. Based on our previous study, a strong synergistic effect of cerium presented in the framework and the surface was existing in Mn-Ce/CeAPSO-34 catalyst, which showed outstanding SO2 tolerance and H2O resistance in the low-temperature NH3-SCR. In situ FT-IR and DFT calculations were used to investigate the synergistic effects. Based on the characterization results of in situ FT-IR study, it was found that more amount of nitrate species and NH3 species adsorbed on the surface of Mn-Ce/CeAPSO-34, while less the amount of sulfate species deposited during reaction process, which in the presence of SO2. Meanwhile, DFT calculations revealed that Ce site supported on the surface, which neighbored by Ce site in the framework more were capable of reacting with NO and NH3.

Simple fabrication of rough halloysite nanotubes coatings by thermal spraying for high performance tumor cells capture

Here, we reported a fast, low-cost, and effective fabrication method of large-area and rough halloysite nanotubes (HNTs) coatings by thermal spraying of HNTs ethanol dispersions. A uniform HNTs coating with high transparence is achieved with tailorable surface roughness and thickness. Compared with normal cells, the tumor cells can be captured effectively with high capture yield by the HNTs coatings (expect HeLa cells), which is attributed to the enhanced topographic interactions between HNTs coating and cancer cells. HNTs coating formed from 2.5% ethanol dispersions shows the highest tumor cells capture yeild (90%), which is related to the appropriate roughness and anti-EpCAM conjugation. The capture yield of HNTs coating towards MCF-7 cells can be further improved to 93% within 2h under dynamic shear using a peristaltic pump. The capture yield increases with the incubation time, and the flow rate with 1.25mL/min leads to the maximum capture yield. The HNTs coatings are also effective for capture of tumor cells spiked in artificial blood samples and blood samples from patients with metastatic breast cancer. More than 90% targeted MCF-7 cells and very small amounts of white blood cells are captured by the anti-EpCAM conjugated HNTs coatings from a blood sample. HNTs are further loaded anticancer drug doxorubicin (DOX) and then thermally sprayed into coatings. The MCF-7 cells captured on DOX loaded HNTs coating display significant membrane rupture characteristic and only 3% cell viability after 16h. The high capture efficiency of tumor cells by HNTs coating fabricated by the thermal spraying method makes them show promising applications in clinical circulating tumor cells capture for early diagnosis and monitoring of cancer patients. The high killing ability of the DOX loaded HNTs coating can also be designed as an implantable therapeutic device for preventing tumor metastasis.

Comparative study of the modification of multi-wall carbon nanotubes by gamma irradiation and sonochemically assisted acid etching

Multi-walled carbon nanotubes (CNTs) have been treated with gamma irradiation in air or by using dilute acids (H2SO4/HNO3) combined with 20 kHz ultrasound to compare their effects. The CNT microstructure has been investigated using transmission electron microscopy which revealed that both methods effectively modified the CNTs to overcome aggregation of the nanotubes, resulting in efficient dispersion in ethanol. The nature of the surface modifications was investigated using Raman and FTIR spectroscopies. The introduction of oxygenated species at the CNT surface was detected. At longer treatment times or high ultrasound intensities, the sonochemically assisted acid treatment showed the highest degree of reaction and functionalisation. Modification of the structure with γ-radiation with doses of 100 kGy or 200 kGy also resulted in a reduction of defects, attributed to an annealing and reorganisation process. The observed effects could be correlated with the time and intensity of the ultrasound used or the dose and dose rate of the γ-radiation. Both methods offer the possibility for processes with lower environmental inpact than those that currently exist. Our results also illustrate the importance of careful control over these experimental parameters if optimum results are to be obtained.

Nonaqueous Sol-Gel Synthesis of Anatase Nanoparticles and Their Electrophoretic Deposition in Porous Alumina.

Titanium dioxide (TiO2) nanoparticles were synthesized by nonaqueous sol-gel route using titanium tetrachloride and benzyl alcohol as the solvent. The obtained 4 nm-sized anatase nanocrystals were readily dispersible in various polar solvents allowing for simple preparation of colloidal dispersions in water, isopropyl alcohol, dimethyl sulfoxide, and ethanol. Results showed that dispersed nanoparticles have acidic properties and exhibit positive zeta-potential which is suitable for their deposition by cathodic electrophoresis. Aluminum substrates were anodized in phosphoric acid in order to produce porous anodic oxide layers with pores ranging from 160 to 320 nm. The resulting nanopores were then filled with TiO2 nanoparticles by electrophoretic deposition. The influence of the solvent, the electric field, and the morphological characteristics of the alumina layer (i.e., barrier layer and porosity) were studied.

Nanostructured lime-based materials for the conservation of calcareous substrates

Nanostructured lime-based materials for the conservation of calcareous substrates

Two-Dimensional GeSe as an Isostructural and Isoelectronic Analogue of Phosphorene: Sonication-Assisted Synthesis, Chemical Stability, and Optical Properties

Monochalcogenides of germanium (or tin) are considered as isoelectronic and isostructural analogues of black phosphorus. Here, we demonstrate the synthesis of atomically thin GeSe by direct sonication-assisted liquid phase exfoliation (LPE) of bulk microcrystalline powders in organic solvents. The thickness of the GeSe sheets is dependent on the exfoliation conditions, and highly crystalline few-layer GeSe sheets of 4–10 layer stacks with lateral sizes over 200 nm were obtained. In ambient atmosphere, the LPE sheets deposited on the substrate demonstrate strong resistance against degradation, while decomposition into elemental Ge and Se nanostructures occurs at a moderate rate for ethanol dispersions. Density functional theory calculation together with optical characterizations confirm the blue-shifted bandgap for the GeSe sheets as a result of strong quantum confinement effect. In addition, we show that the few-layer GeSe sheets with favorable optical bandgap allow for efficient solar light harvesting fo...

SURFACE CHARACTER OF IRON OXIDE/CARBON NANOPARTICLES SYNTHESIZED BY SUBMERGED ARC DISCHARGE METHOD IN ETHANOL/UREA MEDIUM

<p>Synthesis of iron oxide nanoparticles modified with carbon has been successfully performed by submerged arc-discharge method in ethanol/urea medium. Iron oxide used in the fabrication process was prepared by iron electrolysis in an electrolyte solution of NaCl. Fabrication of nanoparticles in this method uses two graphite electrodes. One of them was made in a pointed shape and the other graphite electrodes hollowed out and filled with a mixture of iron oxide, graphite and glue silica (as binder) with a ratio of 1:3:1 (w/w/w). The liquid medium used in this method is a mixture solution of ethanol 50% and urea (0%, 10%, 25% and 50%) with a volume ratio of 1:1 (v/v). The crystalline of iron oxide was characterized using X-Ray Diffraction (XRD), compared to JCPDS No. 89-0597, No. 89-0691 and No. 39-1346. Variations in the urea concentration in the liquid medium provided the changes of the surface character of the synthesized nanoparticles. The changes of surface character were analyzed by the Fourier Transform Infra Red (FTIR) spectra and nanoparticle dispersion in water and ethanol. FTIR spectra showed the absorption of Fe-O, CH, CN, C = O, OH and NH at 460-555 cm<sup>-1</sup>, 650-1000 cm<sup>-1</sup>, 1000-1350 cm<sup>-1</sup>, 1640-1680 cm<sup>-1</sup>, 2400-3400 cm<sup>-1</sup>, 3200-3400 cm<sup>-1</sup>, 3100-3500 cm<sup>-1</sup>, respectively. The best hydrophilic surface character achieved when the nanoparticle was synthesized in medium of ethanol 50% with the addition of urea50%. The existence of a functional group attached on the surface of nanoparticles synthesized in ethanol/urea makes these nanoparticles had better dispersion than nanoparticles synthesized in ethanol medium without urea addition.</p>

Aggregation of zein in aqueous ethanol dispersions: Effect on cast film properties

In this study, we evaluate the influence of zein aggregation in aqueous ethanol dispersions on the properties of zein films. The effects of zein concentration, ethanol content and temperature on transmittance of zein dispersions were investigated. Dynamic light scattering was used to measure the degree of zein aggregation in the dispersions. The results indicate that particle size of zein increased with higher zein concentration, lower ethanol level and at lower temperatures. Zein films were prepared by casting from 70% and 90% aqueous ethanol dispersions at different drying temperatures and were evaluated for appearance, thermomechanical and mechanical properties. Higher ethanol levels and higher drying temperatures promoted the formation of more homogenous films. Films made from higher ethanol dispersions had lower glass transition temperatures than those made from lower ethanol dispersions. Moreover, the fragility factor classified the films as strong systems. Mechanical properties of films were measured at different drying temperatures. Stiffer and more resistant films were developed as the drying temperature increased. In conclusion, film properties can be tailored by controlling the composition of the film casting solvent and the drying temperature. Differences in film properties were found to relate to differences in initial degree of aggregation of zein dispersions.

A facile and low-cost preparation of durable amphiphobic coatings with fluoride–silica@poly(methacrylic acid) hybrid nanocomposites

Poor robustness, high cost and complicated preparation are the main barriers to the large-scale industrial application of amphiphobic coatings. A facile and low-cost method to fabricate durable amphiphobic coatings is reported in this work. The coatings were composed of top and bottom paints. The top paint was prepared by the F–Si@PMAA hybrid nanocomposites dispersion. The hybrid nanocomposites with dual structure were prepared via the co-condensation reaction of tetraethoxysilane (TEOS) and 1H,1H,2H,2H-Perfluorodecyl triethoxysilane (HDFTES) on the surface of the presynthesized PMAA nanoparticles in ethanol dispersion. The bottom one was a type of inexpensive car refinishing paint. The resulting coatings could be sprayed onto different substrates. All the coated substrates exhibited good amphiphobicity with superhydrophobicity with the water contact angle greater than 150°, water roll-off angle less than 4°, and high oleophobicity with the oil contact angle greater than 130°. Moreover, all of the prepared coatings exhibited great robustness after water jetting, sand abrasion, and knife scratching. This method can be an effective strategy for fabricating amphiphobic surfaces for practical industrial applications.

The synergistic effects of cerium presence in the framework and the surface resistance to SO 2 and H 2 O in NH 3 -SCR

Abstract Mn-Ce/CeAPSO-34 was prepared, in which cerium was incorporated in the SAPO-34 framework through using a one-step hydrothermal method, while manganese and cerium were supported on the surface by the Ethanol dispersion method. The conversion of NO x in selective catalytic reaction with NH 3 (NH 3 -SCR) over Mn-Ce/CeAPSO-34 catalyst reached nearly 97.7% at 140 °C and remained about 100% in the temperature range of 160–240 °C. Besides, the synergistic effects of cerium in the framework and the surface on the resistance to SO 2 and H 2 O in low-temperature NH 3 -SCR were investigated. The results demonstrated that a strong synergistic effect existed in Mn-Ce/CeAPSO-34 catalyst, which showed outstanding SO 2 tolerance and H 2 O resistance. At the same time, the structural properties and possible metal-support interaction of the catalysts were characterized by XRD, SEM, H 2 -TPR, XPS and TG-DSC. According to the characterization results, Ce could inhibit the deposition of NH 4 HSO 4 on the surface of the catalysts and preferred to react with SO 2 , hence protecting the manganese active sites. Meanwhile, the theoretical results of DFT calculations suggested that Ce site supported on the surface neighbored by Ce site in the framework was more capable of reacting with SO 2 .

Experimental demonstration of nonlinear enhancement in a graphene-deposited microfiber.

Nonlinear enhancement is experimentally demonstrated by depositing graphene scraps from graphene ethanol dispersion onto a tapered microfiber. The enhancement of the nonlinearity is verified by observing the four-wave mixing (FWM) effect in the homemade graphene-deposited microfiber (GDMF). When the incident pump power is 24.2dBm, the FWM conversion efficiency in the GDMF reaches -57.1 dB. Compared to the bare microfiber with the same dimensions, the conversion efficiency is improved by more than 3dB. Our fabricated GDMF provides a simple way to enhance the fiber nonlinearity, and it will be suitable for nonlinear applications such as wavelength conversion and other optical signal processing operations.

Silica-Derived Hydrophobic Colloidal Nano-Si for Lithium-Ion Batteries.

Silica can be converted to silicon by magnesium reduction. Here, this classical reaction is renovated for more efficient preparation of silicon nanoparticles (nano-Si). By reducing the particle size of the starting materials, the reaction can be completed within 10 min by mechanical milling at ambient temperature. The obtained nano-Si with high surface reactivity are directly reacted with 1-pentanol to form an alkoxyl-functionalized hydrophobic colloid, which significantly simplifies the separation process and minimizes the loss of small Si particles. Nano-Si in 5 g scale can be obtained in one single batch with laboratory scale setups with very high yield of 89%. Utilizing the excellent dispersion in ethanol of the alkoxyl-functionalized nano-Si, surface carbon coating can be readily achieved by using ethanol soluble oligomeric phenolic resin as the precursor. The nano-Si after carbon coating exhibit excellent lithium storage performance comparable to the state of the art Si-based anode materials, featured for the high reversible capacity of 1756 mAh·g-1 after 500 cycles at a current density of 2.1 A·g-1. The preparation approach will effectively promote the development of nano-Si-based anode materials for lithium-ion batteries.

Dispersion enhancing effect of sonochemically functionalized graphene oxide for catalysing antioxidant efficacy of curcumin

The non-hazardous sonochemical approach has been developed for the functionalization of graphene oxide (GrO) with 5-Aminoindazole (5-AIND). The formation of f-(5-AIND) GrO is confirmed with 13C solid state NMR, HRXPS, XRD, Raman, TGA, DSC, FTIR etc. The >80% cell viabilities on MCF-7 and Vero cell lines have confirmed the high cytocompatibility of f-(5-AIND) GrO. Additionally, the morphological impact on Vero cell line has evidently confirmed the biocompatibility of f-(5-AIND) GrO. As compared to GrO, the f-(5-AIND) GrO has demonstrated an enhanced antioxidant efficacy of 69.4–72%, evaluated with 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical assay. With a similar objective (0.01–0.05)mL peanut oil based curcumin micro and nanoemulsions have been prepared using ethanol and glycerol as co-solvent and co-surfactant respectively. The prepared emulsions are subsequently characterised with respect to morphological and physicochemical parameters via density, surface tension, viscosity, friccohesity measurement and DLS analysis. Henceforth, with an expectation to achieve higher dispersion, an ethanolic dispersion of f-(5-AIND) GrO has been mixed with curcumin carrying emulsions in 1:1. Notably, the radical scavenging activities (RSA) of the combined formulations are significantly enhanced to an extent of 26.6%.

Tailoring the phase of Li–Al–O nanoparticles by nonaqueous sol–gel chemistry

A facile nonaqueous sol–gel synthesis for Li–Al–O nanoparticles with tunable stoichiometry and phase purity has been developed. Adjusting the reaction conditions, γ-Al2O3, α-Al2O3, LiAl5O8, β-LiAlO2, and γ-LiAlO2 nanoparticles can be synthesized. For the first time, the synthesis of phase-pure nanoscaled β-LiAlO2 is obtained at low temperature. All the products were characterized by X-ray powder diffraction, Fourier-transformed infrared, small-angle X-ray scattering, transmission electron microscopy/scanning electron microscopy, nitrogen sorption and elemental analysis. The extensive characterization points out some main features for the products: phase purity, nanoscale size, high surface area, good thermal stability, and good dispersion in ethanol. These properties are rarely combined in a single product, making the proposed protocol an important tool for the future applications of Li–Al–O nanoparticles in the field of catalysis and absorptive materials. Nonaqueous sol–gel chemistry: an easy and versatile protocol for compositionally tuneable, phase-pure, and high surface area Li–Al–O nanoparticles.

Improving the filler dispersion and performance of silicone rubber/multi-walled carbon nanotube composites by noncovalent functionalization of polymethylphenylsiloxane

In this work, multi-walled carbon nanotubes (CNTs) were noncovalently functionalized with different amount of polymethylphenylsiloxane (PMPS) successfully, and then the products named as PMPS-1/CNTs, PMPS-2/CNTs and PMPS-3/CNTs, respectively, were introduced into silicone rubber (SR) to prepare a series of SR-based composites. Subsequent characterizations were used to analyze the noncovalent functionalization in addition to the thermal oxidative stability and mechanical properties of SR-based composites. The results showed that PMPS was wrapped on CNTs via physical absorption. PMPS/CNTs had good dispersibility in ethanol, and the solutions could remain stable without any visible precipitation even for 6 months. The physical absorption was thought to mainly result from π–π stacking, CH–π interactions and the van der Waals force between PMPS and the sp2 hybridized network of CNTs. Both the thermal oxidative stability and mechanical properties of PMPS/CNTs/SR composites before and after thermal oxidative aging could be improved by noncovalent functionalization of PMPS. For example, compared with CNTs/SR, the tensile strength before and after thermal oxidative aging of PMPS-2/CNTs/SR could be improved by 13 and 62%, respectively. Moreover, it was found that only the appropriate amount of PMPS can maximize the enhancement of noncovalent functionalization.