Polymeric Precursor Solution Research Articles

Patterned Liquid Crystal Polymer Thin Films Improved Energy Conversion Efficiency at High Incident Angles for Photovoltaic Cells.

In this report, micro-patterned silicon semiconductor photovoltaic cells have been proposed to improve the efficiency in various incident sunlight angles, using homeotropic liquid crystal polymers. The anisotropic liquid crystal precursor solution based on a reactive mesogen has good flowing characteristics. It can be evenly coated on the silicon solar cells' surface by a conventional spreading technique, such as spin coating. Once cured, the polymers exhibit asymmetric transmittance properties. The optical retardation characteristics of the coated polymer films can be eventually determined by the applicable coating and curing parameters during the processes. The birefringence of light then influences the optical path and the divergence of any encountered sunlight. This allows more photons to enter the active semiconductor layers for optical absorption, resulting in an increase in the photon-to-electron conversion, and thus improving the photovoltaic cell efficiency. This new design is straightforward and could allow various patterns to be created for scientific development. The experimental results have evidenced that the energy conversion efficiency could be improved by 2-3% for the silicon photovoltaic cells, under direct sunlight or at no inclination, when the liquid crystal polymer precursor solution is prepared at 5%. In addition, the efficiency could be much more significantly improved to 14-16% when the angle is inclined to 45°. The unique patterned liquid crystal polymer thin films provide enhanced energy conversion efficiency for silicon photovoltaic cells. The design could be further evaluated for other solar cell applications.

Bulk and interface engineering with the combined addition of Na+ and E5+ (E = Nb5+, Ta5+) in the design of hematite photoanodes

In this letter, the synergistic effects of multiple element modification through a single polymeric precursor solution in hematite-based photoanodes using Na/Nb and Na/Ta as dopants are evaluated. Linear sweep voltammetry curves showed that the photoelectrochemical response was improved after Na/Nb (or Ta) addition. In both circumstances, an anodic shift (∼200 mV) in the onset potential was noticeable due to surface states created after Nb5+/Ta5+ segregation. The energetic loss caused by Nb (and Ta) segregation was partially restituted by NiFeOx addition due to the passivation of surface states, acting as recombination centers created by pentavalent modifiers. These combined modifications brought a three and four-fold increase for Na0.1HemNb1.5 NiFeOx and Na0.1HemTa1.0NiFeOx respectively. Charge carrier dynamics analysis studied by intensity modulated photocurrent spectroscopy revealed that the PEC enhancement in both systems is mainly associated with improved charge separation efficiency.

Charge dynamics in semiconductors for photoelectrochemical water splitting

This letter focuses on monitoring alterations in the charge carrier dynamics associated with in-situ modifications into hematite photoanodes, employing advanced electrochemical techniques. A simple and scalable polymeric precursor solution, deposited by spin-coating, was employed to synthesize hematite based photoanodes. Among various modifications, Tantalum (Ta+5) shows the most promising results, yielding a hydrogen production rate of 24.0 μmol cm−2h−1 at 1.23VRHE. This is attributed to Ta5+ segregation at hematite grain surface, which facilitates the charge transport efficiency and leads to higher external quantum efficiency. Conversely, sodium (Na+) primarily increases the film thickness with limited observable effects on charge carrier dynamics, while zinc (Zn+2) adversely affects hematite performance due to its negative effect on charge separation efficiency and increased bulk recombination.

Interfacial engineering of hematite photoanodes toward high water splitting performance

Efficient and scalable photoelectrochemical water splitting electrode designs are a challenge. This study focuses on hafnium-modified hematite (X%Hf-HEM) photoanodes, prepared via spin-coating polymeric precursor solutions with varying Hf4+/Fe3+ (mol) ratios (1.0%, 3.0%, 4.0%, and 5.0%) onto fluorine-doped tin oxide substrates. Structural, morphological, and compositional analyses confirm pure hematite phases in all X%Hf-HEM samples. Increasing Hf4+ content correlated with reduced grain size, thickness, and surface roughness due to Hf4+ segregation at grain boundaries during thermal treatment. Hafnium segregation at hematite grain boundaries and hematite|fluorine-doped tin oxide interfaces is confirmed using scanning transmission electron microscopy coupled with energy dispersive spectroscopy. Notably, the 4%Hf-HEM photoanode exhibits exceptional efficiency enhancement, outperforming HEM efficiency by 4.5 times. Gas chromatography results highlight O2 and H2 evolution rates of 14.49 ± 0.09 μmol/cm2/h and 8.1 ± 0.5 μmol/cm2/h, respectively, for 4%Hf-HEM, with a H2/O2 ratio close to 2:1. The charge dynamics investigated from intensity-modulated photocurrent spectroscopy evidence the main Hf4+ effect of improving charge separation, achieving greater efficiency for 4%Hf-HEM. Shifts in valence band maximum from ultraviolet photoelectron spectroscopy measurements indicate surface state presence, supported by ηtransfer trends calculated from intensity-modulated photocurrent spectroscopy. This research presents a scalable, cost-effective approach to multiinterface photoanode development, holding promise for innovative photoelectrochemical water splitting technologies.

Oxide Films and Nanoparticles for Lithium Ion Battery and Oxygen Electrocatalyst Applications

The global energy crisis coupling with the consumption of fossil fuels and the associated environmental issues, has stimulated extensive interest in searching for clean, efficient and sustainable energy storage and conversion systems. In this talk we are going to introduce a novel chemical solution approach for epitaxial thin film deposition and oxide nanoparticle network synthesis. The use of water soluable polymer to bind the metal ions has several advantages. The formation of covalent complexes between the lone pairs on the nitrogen atoms of the polymer and the metal cations make it possible to prepare almost any metal polymer precursor solutions. The unique chemistry and processing design of this technique deliver stable and homogeneous solutions at a molecular level that allows epitaxial growth of high-quality thin films and oxide nanoparticle network materials. Oxygen electrocatalysis, including both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), dominates the performance of the devices. However, the sluggish kinetics of these two reactions limits their performance. Therefore, development of non-precious metal-based oxygen electrocatalysts is greatly demanded. Metal oxides have attracted extensive interest as alternative electrocatalysts due to their low price and good endurance under relatively high temperature, which can be doped with a wide range of cations attributed to their flexible compositions and structures, leading to easy manipulation of their electrocatalytic properties. We study the nanoscale engineering of perovskite oxides and layered oxides in energy conversion/storage devices and focus on the electrode catalyst design and fabrication for boosting ORR and OER electrocatalysis.

Fabrication and characterization of starch-copper nanoparticles/rutin nanofiber hybrid scaffold

Rutin has antiviral, anticancer, anti-inflammatory and heart disease protective activities but its poor solubility plays a critical role in limiting its activity. To relieve this problem, we prepared polyvinylpyrrolidone (PVP) electrospun nanofibers as carrier to release rutin for potential applications. Starch-coated copper nanoparticles were also added to the polymeric precursor solution before electrospinning to increase the activity of rutin. The water soluble monodisperse starch-protected zero-valent copper nanoparticles of about 36 nm diameter have been synthesized by chemical reduction route using starch as green capping agent. The resulting starch coated copper nanoparticles were characterized by transmission electron microscopy and energy dispersive X-ray analysis (EDX). It was found that copper nanoparticles were significantly protected by starch coating. PVP solutions incorporated with rutin and starch capped copper nanoparticles were electrospun at different weight percentages. The nanofibers were characterized by using scanning electron microscopy, energy dispersive spectroscopy, and Raman spectroscopy. We confirmed that copper nanoparticles were embedded in PVP nanofibers. The cytotoxic efficacy of the nanofiber involving starch capped copper nanoparticles and rutin against L929 mouse fibroblast cells was compared using a standard MTT assay. The in vitro release studies were performed using rutin-copper loaded nanofibers through dialysis membrane on the Franz diffusion cells. The nanofiber involving starch capped copper nanoparticles and rutin exhibited no cytotoxicity compared to PVP nanofibers.

Formation of copper oxide II in polymer solution-blow-spun fibers and the successful non-woven ceramic production

Copper oxide II is a p-type semiconductor that can be used in several applications. Focusing on producing such material using an easy and low-cost technique, we followed an acetate one-pot-like route for producing a polymer precursor solution with different acetates:PVP (polyvinylpyrrolidone) weight ratios. Then, composite nanofibers were produced using the solution blow spinning (SBS) technique. The ceramic CuO samples were obtained after a calcination process at 600 °C for 2 h, applying a heating rate of 0.5 °C/min. Non-woven fabric-like ceramic samples with average diameters lower than 300 nm were successfully obtained. SEM images show relatively smooth fibers with a granular morphology. XRD shows the formation of randomly oriented grains of CuO. In addition, FTIR and XRD analyses show the CuO formation before the heat treatment. Thus, a chemical reaction sequence was proposed to explain the results.

Tuning and fixing of uniform Bragg reflection color of gel-immobilized colloidal photonic crystal films

We demonstrate the facile tuning of uniform Bragg reflection color from red to blue by uniaxial compression of gel films containing single-crystalline loosely packed colloidal crystals. The tuned colors can be fixed by photopolymerization of a polymer precursor solution contained in the compressed gel films.

Role of seed layer in van der Waals growth of vanadium dioxide film on mica prepared by chemical solution deposition

Vanadium dioxide (VO2) has unique electrical and optical properties, which have practical applications in many devices. However, preparing high-quality VO2 films and transferring them to flexible substrates by an economic and simple way are still challenging. Functional thin films can be grown on van der Waals (vdW) substrates and then transferred to flexible substrates due to the weak interaction between films and their substrates. Herein, VO2 thin films were grown on mica substrates by using the polymer-assisted deposition technique. By controlling the ion concentration in the polymer precursor solution, a flat seed layer was prepared at the initial growth stage. It was found that the introduction of the seed layer can improve the crystallinity, increase the grain size and reduce the defects of the VO2 thin films. It is believed that less nucleation density and layered growth at the initial growth stage are critical to the formation of large size grains. Our results confirmed that chemical solution deposition can prepared high-quality VO2 films on vdW substrates.

Mixed Dye Removal Efficiency of Electrospun Polyacrylonitrile-Graphene Oxide Composite Membranes.

Exfoliated graphene oxide (GO) was reliably modified with a cetyltrimethylammonium chloride (CTAC) surfactant to greatly improve the dispersity of the GO in a polyacrylonitrile (PAN) polymer precursor solution. Subsequent electrospinning of the mixture readily resulted in the formation of GO–PAN composite nanofibers containing up to 30 wt % of GO as a filler without notable defects. The absence of common electrospinning problems associated with clogging and phase separation indicated the systematic and uniform integration of the GO within the PAN nanofibers beyond the typical limits. After thoroughly examining the formation and maximum loading efficiency of the modified GO in the PAN nanofibers, the resulting composite nanofibers were thermally treated to form membrane-type sheets. The wettability and pore properties of the composite membranes were notably improved with respect to the pristine PAN nanofiber membrane, possibly due to the reinforcing filler effect. In addition, the more GO loaded into the PAN nanofiber membranes, the higher the removal ability of the methylene blue (MB) and methyl red (MR) dyes in the aqueous system. The adsorption kinetics of a mixed dye solution were also monitored to understand how these MB and MR dyes interact differently with the composite nanofiber membranes. The simple surface modification of the fillers greatly facilitated the integration efficiency and improved the ability to control the overall physical properties of the nanofiber-based membranes, which highly impacted the removal performance of various dyes from water.

Successful production of solution blow spun YBCO+Ag complex ceramics

YBCO fabrics composed of nanowires, produced by solution blow spinning (SBS) are so brittle that the Lorentz force produced by induced currents can be strong enough to damage them. On the other hand, it is known that silver addition improves the mechanical and flux pinning properties of ceramic superconductors. Thus, in this work, we show how we successfully obtained a polymeric precursor solution containing YBCO+Ag salts, which can be spun by the SBS route to produce ceramic samples. Yttrium, barium, copper, and silver metal acetates, and polyvinylpyrrolidone (PVP) (in a ratio of 5:1 wt [PVP:acetates]) were dissolved in a solution with 61.5 wt% of methanol, 12 wt% of propionic acid, and 26.5 wt% of ammonium hydroxide, together with 6 wt% of PVP in solution. Three different amounts of silver (10 wt%, 20 wt%, and 30 wt%) were used in YBa2Cu3O7−x. The TGA characterizations revealed a lowering of crystallization and partial melting temperatures by about 30 °C. SEM images show that after burning out the polymer, a fabric composed of nanowires of diameters up to 380 nm is produced. However, after the sintering process at 925 °C for 1 h, the nanowires shrink into a porous-like sample.

Low oxygen pressure synthesis of NdNiO3-δ nanowires by electrospinning

Synthesis of RNiO3 (R = rare earth) nanowires can be interesting as building blocks with potential applications in optoelectronic devices. Here, we describe the synthesis and characterization of NdNiO3-δ (NNO) nanowires produced by electrospinning technique via polymeric precursor solution at relatively low temperature and oxygen pressure. These NNO nanowires were characterized by x-ray diffraction (XRD), x-ray photodetection spectroscopy (XPS), Field Emission Scanning Electron Microscopy (Fe-SEM), Magnetization (M(T)) and electrical resistance (R(T)) measurements. SEM images revealed a granular nanowire microstructure of NNO nanostructures, with a distribution of nanowire diameters ranging from 50 to 150 nm. The NNO nanowires also exhibit granular characteristics with an average grain diameter of 40 nm. The x-ray diffraction patterns of the NNO nanowires indicated that these samples exhibited a high degree of crystallinity and their Bragg reflections can be indexed to an orthorhombic-distorted (Pbnm symmetry) perovskite structure. The crystalline structure seems to be slightly texturized in some Bragg directions and with a slightly strained crystallite. M(T) and R(T) measurement as a function of temperature curves show that these NNO samples present a metal-insulator (MI) transition close to TMI ∼ 198 K, which is usually observed in NNO thin films and bulk samples. The nanostructured shape and these experimental observations can be promising in designing new electronic devices using this strongly correlated oxide.

Tuning the charge carrier density and exciton pair separation in electrospun 1D ZnO-C composite nanofibers and its effect on photodegradation of emerging contaminants

Maximizing anion (carbon) doping is thought to increase the charge carrier density in ZnO and other semiconductor metal oxide photocatalysts. It also enhances the photocatalytic activity of ZnO nanostructures by imparting visible light responsiveness. However, the effect of the carbon source on the doping efficiency, and in turn on the photocatalytic activity of ZnO nanostructures has been overlooked thus far. In this study one dimensional (1D) ZnO-Carbon composite nanofibers were prepared from different polymer (polyacrylonitrile, polystyrene, polyvinylpyrrolidone) precursor solutions and the C-doping efficiency and its effect on the photocatalytic activity were studied. The prepared nanofiber photocatalysts were characterized by XRD, XPS, FE-SEM, BET, TGA, FT-IR, photoelectrochemical and optical analyses techniques. Based on the thermal degradation profile of the polymer sources, the C-doping efficiencies varied among the samples prepared and so does their photocatalytic activity. Caffeine molecule was selected as a model emerging contaminant and its photodegradation was analyzed in the presence of the as-prepared photocatalysts. Upon the C-doping, new energy level was introduced within the bandgap of ZnO that lowers its bandgap energy by 0.35 eV. Additionally, the charge carrier density of ZnO increased and the flat band potential showed positive shift. These, together with the 1D nature of the photocatalysts, enhanced the photocatalytic activity of pristine ZnO by ~58% and 2.8 folds faster kinetics. Mechanistic study showed that hydroxyl radicals were the most active reactive species responsible for the caffeine molecule degradation. This study underscores that the photocatalytic activity of ZnO for the degradation of environmental pollutants can be maximized by C-doping through careful selection of the carbon source.

Formation of Nanocomposite Solid Oxide Fuel Cell Cathodes by Preferential Clustering of Cations from a Single Polymeric Precursor.

Conventional composite cathodes used in solid oxide fuel cells (SOFCs) are fabricated by co-sintering of electrocatalyst and ionic conductor powders at 1100-1250 °C. The relatively high-temperature heat treatments required to ensure bonding among the powders and between the powders and electrolyte results in the formation of resistive phases and coarse microstructures corresponding to short triple-phase boundary (TPB) length and, consequently, low oxygen reduction activity. In the present work, to achieve long TPBs and avoid resistive phase formation, we propose to fabricate nanocomposite La0.8Sr0.2MnO3-Ce0.8Sm0.2O2 (LSM-SDC) and La0.8Ca0.2MnO3-Ce0.8Sm0.2O2 (LCM-SDC) thin film cathodes by a low-temperature method, which involves the use of a single polymeric precursor solution containing all the respective cations. Owing to the molecular level mixing and the liquid lack of any powder-based starting material, we envision that preferential clustering of cations forming nanoscale electrocatalyst and ionic conductor particles will take place upon heat treatment at relatively low temperatures of 600-800 °C. Here, we report for the first time in the literature, a correlation between the heat-treatment temperature-phase evolution-cluster formation-surface chemistry evolution and electrochemical activity of nanocomposite thin film cathodes fabricated from a single polymeric precursor. Our experiments reveal that highest electrochemical activity is achieved when the electrocatalyst phase is poorly crystallized, complete clustering of cations takes place, and A-site dopant segregation at the surface is minimal.

Abstract 999: In vivo breast tumor stiffness and vascular drug delivery recapitulated in a microfluidic tumor-on-a-chip

Abstract Biomimetic tissue engineered microfluidic cancer models offer a higher degree of spatial, temporal and structural precision in controlling the physical parameters and component characteristics of the native tumor microenvironment (TME). Current models working to establish a biomimetic in vitro breast TME are limited by their ability to recapitulate various degrees of in vivo complexities and poor correlation of the diffusional gradients of oxygen, nutrients and anti-cancer drugs. To establish a model and address these challenges, we have used poly(ethylene glycol)-fibrinogen (PEG-Fb) as our biomimetic material to engineer 3D breast tumor tissues and recapitulate the mechanical stiffness of core, midpoint and peripherial zones of the native tumor in a vascularized microfluidic chip. To assess the mechanical stiffness, the in vivo breast tumor (MDA-MB-231 flank xenograft in Athymic nude mice) and engineered tumor constructs were subjected to parallel plate compression test using Cell Scale Microsquisher and the resulting force versus displacement data was acquired to calculate Young’s modulus. Tumor mimetic (“high perfusion chip” (HPC) and “low perfusion chip” (LPC), differ with respect to the vascular network surrounding their respective primary and secondary tumor compartments were used in this study. Breast cancer-associated endothelial cells (hBTEC) were seeded in the vascular network and allowed to form a lumen. Metastatic breast cancer cells MDA-MB-231/ human foreskin fibroblast BJ5ta (ATCC) cells were mixed with polymer precursor solution containing PEG-Fb and Eosin Y. The precursor was loaded into the primary tumor compartment and cross-linked for 2 minutes under visible light. Stiffness was modulated by adding poly(ethylene glycol) diacrylate (PEGDA) to the polymer precursor for recapitulating the different zones of the in vivo tumor. hBTEC media was perfused through the endothelial cell networks were continuously monitored for cell behavior and metastasis. In vivo breast tumor stiffness at core, midpoint and periphery was found to be within the range of the 3D engineered breast tumor tissues with time in culture through day 29. In the vascularized microfluidic chip, cell laden biomaterial was incorporated, the cancer cells were observed to undergo key events of the TME such as intravasation, circulating tumor cells in the endothelial vascular channel, adherence and migration to the secondary chamber resulting in metastasis. In the native TME there are regional differences in drug diffusion; TRITC dextran (4.4 kDa) was administered at a constant flow rate through the chips’ vascularized networks and found to have vascular network geometry and engineered tumor construct stiffness dependent differences in diffusion into the primary tumor chamber, mimicking the in vivo phenomena. Citation Format: Benjamin Anbiah, Iman Hassani, Nicole Habbit, Lani Jasper, Deborah Ramsay, Balabhaskar Prabhakarpandian, Robert Arnold, Elizabeth Lipke. In vivo breast tumor stiffness and vascular drug delivery recapitulated in a microfluidic tumor-on-a-chip [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 999.

Improvement of Sensing Performance of Impedancemetric C₂H₂ Sensor Using SmFeO₃ Thin-Films Prepared by a Polymer Precursor Method.

A sensitive an impedancemetric acetylene (C2H2) gas sensor device could be fabricated by using perovskite-type SmFeO3 thin-film as a sensor material. The uniform SmFeO3 thin-films were prepared by spin-coating and focusing on the effects of polymer precursor solutions. The prepared precursors and thin-films were characterized by means of thermal analysis, Fourier-transform infrared spectroscopy, ultraviolet–visible spectroscopy, X-ray diffraction analysis, scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that particle growth and increase in homogeneity of the prepared thin-film could be accelerated by the addition of acetyl acetone (AcAc) as a coordination agent in the polymer precursor solution. Moreover, the highly crystallized thin-film-based sensor showed good response properties and stabilities to a low C2H2 concentration between 0.5 and 2.0 ppm.

Synthesis of (Bi,Pb)-2223 superconductor powder by pechini method

In this paper, we present a detailed route of synthesis to produce ceramic superconductor Bi1,6Pb0,4Sr2Ca2Cu3Ox (Bi,Pb)-2223 powder by Pechini method. The obtained polymeric precursor solution was produced by using inexpensive chemical reagents, which showed a great stability for three weeks with high concentration of BPSCCO inorganic ions. The crystallization kinetic of BPSCCO powder was investigated by thermal analysis (DSC/TGA) and X-ray diffraction (XRD) techniques. The thermal treatment of the BPSCCO powder at different temperatures showed that complex phase equilibrium occurs to the system. The three superconductor phases seems to coexist in a large range of temperature, the Bi-2201 phase was crystallized around 500 oC and then, after 840 oC the desirable (Bi,Pb)-2223 phase appears with coexistence of the Bi-2212 phase at low quantity. Finally, the powder morphology was characterized by scanning electron microscopy (SEM), the results point to a typical plate like formation of the grains.

Performance Enhancement of La0.3Ca0.7Fe0.7Cr0.3O3-δ Air Electrodes by Infiltration Methods

Our recent studies have shown that La0.3Ca0.7Fe0.7Cr0.3O3-δ (LCFCr) is an extremely promising material for use as an air electrode in reversible solid oxide cells (RSOFCS), due to its excellent activity towards the oxygen reduction and evolution reactions. LCFCr has also been shown to be a very active catalyst for CO2/CO reactions at the fuel electrode, thus making it a good candidate for use in symmetrical RSOFCs. In the present work, GDC and GDC + LCFCr polymeric precursor solutions were infiltrated into a porous LCFCr scaffold to further enhance the performance, producing a high surface area, nanoporous coating on the LCFCr surface. GDC infiltration resulted in a ca. 2-fold decrease in polarization resistance, specifically lowering the high frequency resistance, which is associated with the electrode/electrolyte interface. When the porous LCFCr electrode structure was co-infiltrated with GDC + LCFCr, the resistance of both the high and low frequency processes decreased, which according to our model, indicates that the quality of both the electrode/electrolyte (high frequency) and solid/gas (low frequency) interfaces were improved. Overall, it was shown to be possible to reduce the polarization resistance of the LCFCr air electrode by up to ca. 2.5 times using these infiltration approaches.

Innovative Oxygen Selective Membrane for Li-Air Battery Operating in Ambient Air

The demand for high-energy storage systems is constantly increasing, as is the interest to explore alternatives to commercially available batteries. The rechargeable Li-air battery represents an exciting opportunity to design batteries that may satisfy some of the requirements of our future by coupling the light Li metal with the inexhaustible source of O2 of the surrounding air, resulting in high theoretical specific energy density. Currently, most of the researches on the Li-air battery comprise a cell fed with pure O2 allowing that way to maintain long-term operation, owing to the high O2 concentration free of contaminants. However, for many practical applications such as EV, air is the only viable option to supply the battery. In this context, moisture and gases other than O2 may cause side reactions and corrosion. Herein, we report a facile strategy to fabricate an effective oxygen selective membrane with poly(vinylidene fluoride co-hexafluoropropylene) (PVDF-HFP) via non-solvent induced phase separation, casted as a 240 micron thin sheets for cell protection in ambient air condition. The use of different additives helps enhancing the barrier properties as well as the membrane specificity toward O2. For instance, sacrificial silica nanoparticles (SiO2 NPs) were incorporated into the precursor solution to create a controlled alveolar-like structure inside the membrane. The membrane was loaded with polydimethylsiloxane (PDMS) under vacuum. Another kind of additive considered is the cyclodextrine. Indeed, thanks to their unique structure, cyclodextrines are able to form host-guest complexes with hydrophobic molecules such as our polymer matrix. Nanosponges based on cyclodextrines were prepared and added to the polymer precursor solution before membrane casting. The as prepared membranes showed higher oxygen permeability and lower water permeability. Galvanostatic charge-discharge cycling tests of a Li-air pouch cell in a potential/time controlled mode showed an outstanding cycling life superior to 1500h with more than 150 cycles.

Photoelectron yield spectroscopy and inverse photoemission spectroscopy evaluations of p-type amorphous silicon carbide films prepared using liquid materials

Phosphorus-doped amorphous silicon carbide films were prepared using a polymeric precursor solution. Unlike conventional polymeric precursors, this polymer requires neither catalysts nor oxidation for its synthesis and cross-linkage, providing semiconducting properties in the films. The valence and conduction states of resultant films were determined directly through the combination of inverse photoemission spectroscopy and photoelectron yield spectroscopy. The incorporated carbon widened energy gap and optical gap comparably in the films with lower carbon concentrations. In contrast, a large deviation between the energy gap and the optical gap was observed at higher carbon contents because of exponential widening of the band tail.