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Ionic covalent organic frameworks (iCOFs) are promising materials for energy storage devices due to their ionic functional groups, which facilitate ion transport, and their highly ordered pores of their frameworks, which provide ideal pathways for long-term ion transport under harsh electrochemical conditions. In this study, we attempted for the first time to synthesize an unprecedented iCOF using a heteroatom-embedded mellitic triimido COF framework that enables practical ion channels on the Angstrom scale. This iCOF was subsequently evaluated as an anhydrous proton-conducting material. The heterocyclic pyridine group of the 2,5-diaminopyridine (DAPy) linker plays an important role, not only as an AB stacking-inducing group but also as a proton acceptor that interacts with impregnated H3PO4. The resulting PA@MTI-DAPy-COF exhibited high proton conductivity of 3.68 × 10–2 S cm–1 at 150oC under anhydrous conditions. This work paves the way for constructing efficient proton-conducting channels by leveraging the stacking structure of COF skeletons. [ABSTRACT FROM AUTHOR]

Li2S–P2S5–LiI-type solid electrolytes, such as Li4PS4I, Li7P2S8I, and Li10P3S12I, are promising candidates for anode layers in all-solid-state batteries because of their high ionic conductivity and stability toward Li anodes. However, few studies have been conducted on their detailed local structure and particle surface state. In this study, Li7P2S8I (Li2S: P2S5:LiI = 3:1:1) solid electrolytes as the chemical composition were synthesized by mechanical milling and liquid-phase shaking, and their local structures were analyzed by transmission electron microscopy. The particle surface states were analyzed by X-ray photoelectron spectroscopy, high-energy X-ray scattering measurements, and neutron total scattering experiments. The results showed that Li7P2S8I solid electrolytes are composed of nanocrystals, such as Li4PS4I, LiI, Li10P3S12I and an amorphous area as the main region, indicating that the crystalline components alone do not form ionic conductive pathways, with both the amorphous and crystalline regions contributing to the high ionic conductivity. Moreover, the ionic conductivity of the crystalline/amorphous interface of the glass-ceramic was higher than that of the Li2S–P2S5–LiI glass. Finally, an organic-solvent-derived stable surface layer, which was detected in the liquid-phase shaking sample, served as one of the factors that contributed to its high stability (which surpassed that of the mechanically milled sample) toward lithium anodes. We expect these findings to enable the effective harnessing of particle surface states to develop enhanced sulfide solid electrolytes. [ABSTRACT FROM AUTHOR]

In this study, polymer-coated anisotropic inorganic nanowires dispersed in PBI matrix were introduced to construct 1D proton conducting channels within PBI. Ionic-liquid and solvothermal methods were used for the synthesis of ZrO2 and W18O49 NWs, which were coated with PVPA and PDDA polymers to increase their proton conductivity. Our results showed that, prepared membranes have amorphous nature due to the dominating presence of PBI. SEM analysis revealed the average thickness of membrane of about 36 µm. TG/DTA analysis detected lower weight loss of W18O49 NWs (total 2.8%) compared to ZrO2 NWs (18%). Proton conductivity analysis showed that, PDDA/W18O49 NWs possess relatively 4 times higher proton conductivity (4 × 10−4 Scm−1) compared to PDDA/ZrO2 NWs (1 × 10−4 Scm−1) at 80 ℃. In addition, PDDA-coated W18O49 NWs dispersed PBI membranes showed the highest fuel cell current density (1.2 A/cm2) and power density (215 mW/cm2) at 150 ℃ after 24 h which is nearly 2.5 times higher than pure PBI membrane. In addition, they exhibited the lowest in-situ proton resistance of about (0.47 Ω) compared with that of pure PBI membrane (0.8 Ω). Our results are introducing new concepts towards the development of thin and efficient polymer electrolyte membranes for PEM fuel cells. [ABSTRACT FROM AUTHOR]

Anodic TiO2 nanotube arrays (TNTAs) have attracted much attention due to their excellent photoelectrochemical (PEC) properties. In this work, the tube length of TNTAs was optimized for efficient PEC water splitting under two different conditions, in which very few or a massive amount of gas bubbles were generated on the electrodes. As a result, relatively longer TNTAs were found to be preferable for higher PEC performance when a larger number of bubbles were generated. This suggests that the mass transport in the electrolyte is assisted by the generated bubbles, so that the electrode surfaces are more easily exposed to the fresh electrolyte, leading to the higher PEC performance. [ABSTRACT FROM AUTHOR]

Monodispersed silica (SiO2) nano- and microparticles can be fabricated by the sol-gel process. For device fabrication, precise formation of composite particles with a homogeneous and facile arrangement that form well-ordered, close-packed arrays is important. In this study, formation of electrostatically assembled SiO2–SiO2 composite particles with excellent homogeneity in arrangement was first demonstrated using sol-gel-derived monodispersed SiO2 particles with average particles sizes of 200 nm and 16 µm. Formation of two- and three-dimensionally, close-packed arrays by electrophoresis-induced stimulation with direct-current and alternating-current electric fields was achieved for the first time using these electrostatically assembled SiO2–SiO2 composite particles. Detailed morphological observation by scanning electron microscopy revealed that the structure of the SiO2–SiO2 composite particles remained intact even after electrophoretic stimulation. The feasibility of obtaining well-ordered arrays of electrostatically assembled sol–gel-derived SiO2–SiO2 composite particles is important for further development of sol-gel-related technology in various applications, such as advanced composites and optical devices. Highlights: Electrostatically assembled SiO2–SiO2 composite particles were prepared using monodispersed sol–gel-derived SiO2 particles with two sizes. Ordered two- and three-dimensional SiO2–SiO2 composite-particle arrangements were obtained. Superimposition of AC and DC electric fields through electrophoresis-induced stimulation generated a two-dimensional close-packed structure. Simultaneous gravitational sedimentation and AC field application led to formation of three-dimensionally ordered arrays. [ABSTRACT FROM AUTHOR]

In this study, nanoporous anodic film was produced by anodization of niobium, Nb in a fluoride ethylene glycol electrolyte. The effect of anodization voltage and electrolyte temperature was studied to find an optimum condition for circular, ordered, and uniform pore formation. The diameter of the pores was found to be larger when the applied voltage was increased from 20 to 80 V. The as-anodized porous film was also observed to comprise of nanocrystallites which formed due to high field-induced crystallization. The nanocrystallites grew into orthorhombic Nb2O5 after post-annealing treatment. The Cr(VI) photoreduction property of both the as-anodized and annealed Nb2O5 samples obtained using an optimized condition (anodization voltage: 60 V, electrolyte temperature: 70 °C) was compared. Interestingly, the as-anodized Nb2O5 film was found to display better photoreduction of Cr(VI) than annealed Nb2O5. However, in terms of stability, the annealed Nb2O5 presented high photocatalytic efficiency for each cycle whereas the as-anodized Nb2O5 showed degradation in photocatalytic performance when used continually. [ABSTRACT FROM AUTHOR]

A variety of nanomaterials that interact with light and exhibit localized surface plasmon resonance (LSPR) have been developed. In this chapter, a brief overview of LSPR is provided in relation to the shape and assembly state of plasmonic nanomaterials. Then, LSPR-based optical devices, such as surfaceenhanced Raman scattering substrates, polarizers, hologram recording media, solar cells, and photocatalysts, prepared in the authors’ laboratory are introduced. [ABSTRACT FROM AUTHOR]

3Li2S–1P2S5–xLiI (x = 0, 0.5, 0.9, 1) solid electrolytes were synthesized by liquid-phase shaking methods using ethyl propionate as a reaction medium. The X-ray diffraction results showed that the main phase at both x = 0.9 and 1.0 was Li4PS4I. The highest ionic conductivity at 25 °C was 7.8 × 10−4 S cm−1 for 3Li2S–1P2S5–0.9LiI (Li6.9P2S8I0.9), although it was 6.4 × 10−4 S cm−1 for 3Li2S–1P2S5–1LiI (Li7P2S8I). Despite the lower ionic conductivity of 3Li2S–1P2S5–1LiI (Li7P2S8I), it exhibited a better stability toward Li metal than 3Li2S–1P2S5–0.9LiI (Li6.9P2S8I0.9), indicating that the amount of LiI strongly affects the stability of the electrolyte against Li metal. In addition, 3Li2S–1P2S5–1LiI (Li7P2S8I) was employed in both the cathode composite and separator in the all-solid-state battery in which LiNbO3 coated-LiNi1/3Mn1/3Co1/3O2 and Li were used as cathode and anode, respectively. The all-solid-state battery showed the reversible capacity of approximately 140 mAh g−1, indicating that 3Li2S–1P2S5–1LiI (Li7P2S8I) solid electrolyte is suitable for an all-solid-state Li metal battery. Highlights: 3Li2S–1P2S5–xLiI solid electrolytes were synthesized by liquid-phase shaking methods. The amount of LiI strongly affects the stability against Li metal. The all-solid-state battery using Li7P2S8I showed a reversible capacity of 140 mAh g−1. [ABSTRACT FROM AUTHOR]

TiO2 nanotubes (TNTs) with self-aligned 7.25 ± 0.51-µm length, 66.78 ± 4.18-nm diameter, and 41.48 ± 4.31-nm wall thickness were fabricated using Ti wire in an anodic process using an ethylene glycol (EG)/NH4F–air bubbles electrolyte. The possible growth of TNTs in the electrolyte with different water content was explored. It was found that the growth rate of TNTs in an electrolyte with air bubbles and no water content was significantly faster than that in an electrolyte with 1–5-vol% water content. The degradation of methylene blue (MB) dye with sodium borohydride (NaBH4) as the sacrificial reagent (hole scavenger) under ultraviolet (UV) irradiation was investigated in a photocatalytic study of 400 °C annealed optimized TNTs. The results showed that TNTs can reduce MB at approximately 99%, 74%, and 40% removal efficiency using the first, second, and third cycles, respectively, for 70-min reaction time each. A kinetic study revealed that the photoreduction process followed the pseudo-first-order kinetic with reaction rates of 0.0280, 0.0213, and 0.0052 min−1 for the first, second, and third cycles, respectively. This study's findings will provide new insights into the design of UV light induced on anodized TNTs using Ti wire in EG/NH4F electrolytes with air bubbles aided by NaBH4 for the degradation of MB dye. [ABSTRACT FROM AUTHOR]

Synthesis technology for sulfide-based solid electrolytes based on liquid-phase processing has attracted significant interest in relation to achieving the optimal design for all-solid-state batteries. Herein, guidelines to solvent selection for the liquid-phase synthesis of superionic conductor Li7P3S11 are described through systematic examination. 70Li2S–30P2S5 system, a source of Li7P3S11, is treated via a wet chemical reaction using eight organic solvents with different physical and chemical properties (i.e., dielectric constant, molecule structure, and boiling point). We reveal that the solvent's polarity, characterized by the dielectric constant, plays an important role in the formation of crystalline Li7P3S11 via wet chemical reaction. In addition, acetonitrile (ACN) solvent with a high dielectric constant was found to lead to high-purity crystalline Li7P3S11 and intrinsically high ionic conductivity. Further, solvents with a high boiling point and ring structures that cause steric hindrance were found to be unfavorable for the wet chemical synthesis of Li7P3S11 solid electrolyte. Overall, we demonstrate that ACN solvent is the most suitable for the liquid-phase synthesis of a crystalline Li7P3S11 solid electrolyte with high purity based on its dielectric constant, molecular structure, and boiling point. [ABSTRACT FROM AUTHOR]

In this article, we have demonstrated single-step as well as scalable synthesis of zinc oxide nanoparticles (ZnO NPs) supported on highly thin/transparent reduced graphene oxide (rGO) nanocomposite (ZnO@rGO) via direct microwave irradiation using decomposition of zinc acetate dihydrate (Zn(CH3CO2)2·2H2O) along with reduction of graphite oxide. The surface microstructure of prepared ZnO@rGO nanocomposite was analyzed by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, and X-ray photo electron spectroscopy. Different characterization analysis indicates that the ZnO NPs in the nanocomposite were dispersed on the surfaces of rGO nanosheets (NSs). Raman spectra reveal the structural defects level of rGO NSs was 0.78, while it was increased to 1.66 for ZnO@rGO nanocomposites. The synthesized ZnO@rGO nanocomposite exhibits specific capacitance of 102.4 F/g at the scan rate of 30 mV/s and shows good cyclic stability of 82.5% for 3000 cycles at high scan rate 100 mV/s. [ABSTRACT FROM AUTHOR]

In this study, silver nanoparticles (AgNPs) conductive filler was attached on polydimethylsiloxane (PDMS) substrate to produce resistive-type strain sensors. The sandwich-structured-like PDMS covered AgNPs strain sensors (Ag-PDMS) and AgNPs modified PDMS composite strain sensors (Ag@PDMS) were fabricated by a drop-casting method. The effect of AgNPs loading such as 0.20 wt%, 0.25 wt%, and 0.30 wt% with PDMS was investigated and electromechanical performance were compared between Ag-PDMS and Ag@PDMS composite strain sensors. Based on the strain performance, the gauge factor of strain sensor fabricated with AgNPs loading with 0.25 wt% in PDMS (Ag0.25@PDMS) composite revealed the gauge factor of 10.08 with a strain range of 70%, which demonstrated fast time response, good stretchability, durability, and repeatability. Ag0.25@PDMS composite strain sensor fabricated in the present study is able to be used in finger motion detection, which indicates the capability of the sensor to be used for human body motion capture and other highly sensitive strain-sensing applications. [ABSTRACT FROM AUTHOR]

Water scarcity is now a serious global issue resulting from population growth, water decrease, and pollution. Traditional wastewater treatment plants are insufficient and cannot meet the basic standards of water quality at reasonable cost or processing time. In this paper we report the preparation, characterization and multiple applications of an efficient photocatalytic nanocomposite (CoxNi1−xFe2O4; x = 0.9/SiO2/TiO2/C-dots) synthesized by a layer-by-layer method. Then, the photocatalytic capabilities of the synthesized nanocomposite were extensively-studied against aqueous solutions of chloramine-T trihydrate. In addition, reaction kinetics, degradation mechanism and various parameters affecting the photocatalytic efficiency (nanocomposite dose, chloramine-T initial concentration, and reaction pH) were analyzed in detail. Further, the antimicrobial activities of the prepared nanocomposite were tested and the effect of UV-activation on the antimicrobial abilities of the prepared nanocomposite was analyzed. Finally, a comparison between the antimicrobial abilities of the current nanocomposite and our previously-reported nanocomposite (CoxNi1−xFe2O4; x = 0.9/SiO2/TiO2) had been carried out. Our results revealed that the prepared nanocomposite possessed a high degree of crystallinity, confirmed by XRD, while UV–Vis. recorded an absorption peak at 299 nm. In addition, the prepared nanocomposite possessed BET-surface area of (28.29 ± 0.19 m2/g) with narrow pore size distribution. Moreover, it had semi-spherical morphology, high-purity and an average particle size of (19.0 nm). The photocatalytic degradation efficiency was inversely-proportional to chloramine-T initial concentration and directly proportional to the photocatalyst dose. In addition, basic medium (pH 9) was the best suited for chloramine-T degradation. Moreover, UV-irradiation improved the antimicrobial abilities of the prepared nanocomposite against E. coli, B. cereus, and C. tropicalis after 60 min. The observed antimicrobial abilities (high ZOI, low MIC and more efficient antibiofilm capabilities) were unique compared to our previously-reported nanocomposite. Our work offers significant insights into more efficient water treatment and fosters the ongoing efforts looking at how pollutants degrade the water supply and the disinfection of water-borne pathogenic microorganisms. [ABSTRACT FROM AUTHOR]

The significance of graphene and its two-dimensional (2D) analogous inorganic layered materials especially as hexagonal boron nitride (h-BN) and molybdenum disulphide (MoS2) for "clean energy" applications became apparent over the last few years due to their extraordinary properties. In this review article we study the current progress and selected challenges in the syntheses of graphene, h-BN and MoS2 including energy storage applications as supercapacitors and batteries. Various substrates/catalysts (metals/insulator/semiconducting) have been used to obtain graphene, h-BN and MoS2 using different kinds of precursors. The most widespread methods for synthesis of graphene, h-BN and MoS2 layers are chemical vapor deposition (CVD), plasma-enhanced CVD, hydro/solvothermal methods, liquid phase exfoliation, physical methods etc. Current research has shown that graphene, h-BN and MoS2 layered materials modified with metal oxide can have an insightful influence on the performance of energy storage devices as supercapacitors and batteries. This review article also contains the discussion on the opportunities and perspectives of these materials (graphene, h-BN and MoS2) in the energy storage fields. We expect that this written review article including recent research on energy storage will help in generating new insights for further development and practical applications of graphene, h-BN and MoS2 layers based materials. [ABSTRACT FROM AUTHOR]

A Li7P2S8I solid electrolyte was prepared by the reaction between raw materials in an ethyl propionate medium and drying of the precursor. The obtained sample was characterized by X-ray diffraction (XRD), cyclic voltammetry, DC polarization test and AC impedance measurements. The formation of Li7P2S8I was confirmed from the results of XRD. Cyclic voltammetry and the DC polarization test indicated that the obtained Li7P2S8I was stable at low potential versus Li/Li+ and against Li metal. The all-solid-state lithium-ion battery was fabricated by using Li–In, Li7P2S8I solid electrolyte and a graphite composite that was prepared by mixing graphite, Li7P2S8I solid electrolyte and vapor grown carbon fiber with a vortex mixer. It was observed that the electrode materials were homogeneously mixed from the scanning electron microscopy image of the composite prepared by using the vortex mixer. The fabricated half-cell was characterized by the charge–discharge test. The Li7P2S8I solid electrolyte is suitable for use with a graphite anode because the charge–discharge test exhibited an initial discharge capacity of 372 mA h g−1 and high reversibility of capacity. [ABSTRACT FROM AUTHOR]

The precursor of plate-like LiPS solid electrolyte (75LiS▪25PS, SE (LS)), about 3 μm in length, 500 nm in width, and 100-200 nm in thickness, was successfully prepared from LiS and PS using ethyl propionate (EP) as a synthetic medium via liquid-phase shaking. Upon evacuating at 170 °C, the precursor decomposed to SE (LS), which exhibited ionic conductivity of about 2.0 × 10 Scm at room temperature. SEM observation revealed that the SE (LS) thus obtained had plate-like morphology with dimension of 3 μm in length, 500 nm in width, and 100-200 nm in thickness. Owing to the nanosized SE (LS), an all-solid-state half-cell using composite anode consisting of 90 wt% LiNiMnCoO (NMC) and 10 wt% SE (LS) delivered a high capacity up to 130 mAhg(NMC) at the first discharge. [ABSTRACT FROM AUTHOR]

The effects of annealing temperatures on the structure and photocurrent response of nanoporous iron oxide film prepared by anodization of iron foil in an ethylene glycol, NH4F, and H2O electrolyte were studied. The as-anodized anodic film was found to be rather amorphous and crystallized to predominantly α-Fe2O3 upon annealing in nitrogen. Nitrogen was used as to reduce the thickening of the barrier layer which affects the photocurrent response of the oxide. However, annealing must be done above 300 °C to produce crystalline oxide but must be kept lower than 500 °C since high temperature promotes grain growth, destroying the nanoporous structure and also thickens the barrier layer, which significantly reduce the photocurrent of the film. Sample annealed at 450 °C in nitrogen has the highest photocurrent of 1.04 mA/cm2 (0.5 V versus Ag/AgCl in 1 M NaOH) compared to 0.13 mA/cm2 at 0.5 V for air-annealed sample. [ABSTRACT FROM PUBLISHER]

A mesoporous SiO template containing TiO nanocrystals is synthesized via a sol-gel route, and Au nanoparticles (NPs) are deposited in the tubular mesochannels of the template by a photodeposition method (Au/SiO-TiO). Both of the photocatalytic activities under ultraviolet (UV) and visible (Vis) light irradiation are improved by the deposition of Au NPs. A commercially available photocatalyst, Degussa P25 is employed as a reference, and a comparative study shows that Au/SiO-TiO possesses higher photocatalytic activity than that of P25. An action spectrum of methylene blue (MB) photobleaching using Au/SiO-TiO reveals that the photocatalysis of Au/SiO-TiO is carried out by three triggers: UV absorption by TiO and Vis light absorptions by Au NPs and MB. Graphical abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Highly oriented edge exposure MoS nano flakes were successfully synthesized via reaction between MoO powder and S vapor at 700 °C for 2 h. The received MoS flakes were characterized with SEM, TEM/HR-TEM, Raman spectroscopy, and XRD. TEM result shows that MoS flakes are ~100 nm in diameter and compose of <10 layers (<5 nm). XRD and HR-TEM also prove that prepared MoS flakes are highly crystallized with typical honeycomb structure. [ABSTRACT FROM AUTHOR]

The volatilization of bismuth (Bi) species and bismuth oxide (Bi2O3) leads to the presence of the oxygen vacancies (V000) and consequently restrains the properties of bismuth titanate (BIT; Bi4Ti3O12). This report presents the incorporation of different atomic ratios of praseodymium ion (Pr: x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) into the BIT (Bi4-xPrxTi3O12) ceramics through an intermediate fuel agent-assisted self-combustion synthesis (IFSC). X-ray diffraction and Raman spectroscopy results revealed that some of bismuth ion (Bi3+) in the pseudo-perovskite layer containing Ti-O octahedra was substituted by Pr3+ ion. The substitution by ion with a smaller ionic radius caused the structure distortion and consequently resulted in the phase transformation from an orthorhombic symmetry to a tetragonal symmetry. Besides, it suppressed the volatilization of Bi and Bi2O3 and increased the stability of metal-oxygen octahedra in the BIT. These play a crucial role to control the crystal growth, as well as limit the V000. Dense ceramic with a relative density up to 96.2% was obtained by incorporating Pr with atomic ratio of 1.0. It exhibited high dielectric constant as 908.19 and low dissipation factor as 0.0011. The results address the possibility to control the structure, morphology and dielectric properties of BIT ceramic by incorporating Pr ion through IFSC. [ABSTRACT FROM AUTHOR]

New inorganic-organic hybrid materials were synthesized by hydrolysis and condensation of cyanopropyltriethoxysilane (CNPrTEOS) and polydimethylsiloxane (PDMS) in the presence of hydrochloric acid, HCl catalyst and methyl trimethylmethoxysilane as precursor via sol-gel method and coated on glass encased stir bar for use in stir bar sorptive extraction (SBSE). The cyano part provides polar moiety, which may improve the extraction of polar analytes. The physico-chemical properties and extraction ability of PDMS-CNPrTEOS-derived hybrid coatings can be fine tuned via manipulation of solvents (tetrahydrofuran (THF)-based and dichloromethane (DCM)-based) and PDMS-CNPrTEOS molar concentrations during the sol synthesis. Clear, homogeneous PDMS-CNPrTEOS-derived hybrid sols were obtained using THF and DCM at optimized molar ratios. The optimized molar ratios of THF:CNPrTEOS and THF:PDMS were 5:1 and 25:1, respectively. The optimized molar ratios of DCM:CNPrTEOS and DCM:PDMS were 10:1 and 70:1, respectively. FTIR spectrum showed that the intensity of the CN peak increased with increasing content of CNPrTEOS in the PDMS;CNPrTEOS-derived hybrid. The Field Emission Scanning Electron micrographs of prepared coatings revealed smooth, homogenous surfaces and crack-free coatings with film thickness of 200 nm to 2.5 μm attributing to different solvent types. All coatings prepared were thermally stable at temperature higher than 200 °C. The DCM-based PDMS-CNPrTEOS-derived coating shows more advantages in terms of physical characteristics and extraction ability compared to THF-based PDMS-CNPrTEOS-derived coatings due to higher cyano part content and its thicker coating. The PDMS-CNPrTEOS-derived hybrid coatings can be used as extraction sorbent for analysis of non steroidal anti-inflammatory drugs namely ketoprofen and diclofenac sodium in SBSE. [ABSTRACT FROM AUTHOR]

SiO·TiO coatings were prepared by a sol-gel route. The effect of the external fields including mechanical vibration and electric charge applied during hot-water treatment on titania precipitation at the surface of the coatings was investigated. The shape of the resulting precipitates tended to elongate by applying vibration in a parallel or perpendicular direction, or by applying an electric charge. The organization of titania nanocrystallites possibly occurs because of the concentration gradient of dissolved titania species generated by the external fields during the hot-water treatment. A maximum aspect ratio of 38.1 was achieved for the precipitate prepared by hot-water treatment performed under parallel vibration for 5 h. The shape of the resulting precipitates was also influenced by the content of TiO in the SiO·TiO coating, with a smaller proportion of TiO increasing the aspect ratio of the resulting precipitate. [ABSTRACT FROM AUTHOR]

SiO2–TiO2 spherical microparticles of about 0.7 μm in diameter were prepared by the sol–gel method. Anatase nanocrystals were formed in the microparticles and their specific surface area was increased after a hot-water treatment at 90 °C. From the changes in the concentration of I2 photocatalytically generated from KI aqueous solution, the activity of the SiO2–TiO2 microparticles was found to increase with increasing the hot-water treatment time. Particulate, thick films were electrophoretically deposited on indium tin oxide (ITO)-coated glass substrates using the anatase nanocrystal-precipitated SiO2–TiO2 microparticles. The thickness of the electrophoretically deposited particulate film increased to be approximately 10 μm with an increase in applied voltage. The resultant thick film showed a high photocatalytic activity. [ABSTRACT FROM AUTHOR]

Considerable amounts of anatase nanocrystals were formed on the (100 - x)SiO2·xTiO2 coatings with x of 16.5 and 25 mol% with boiling water treatment, whereas the formation of anatase nanocrystals was not clearly observed for the coatings with x of 50 and 75 mol%. Despite the lower TiO2 content, the coatings with x of 16.5 and 25 mil% showed higher concentration of Si-O-Ti bonds among the coatings. Thus, the hydrolysis of Si-O-Ti bonds and resultant sites should facilitate the nucleation and growth of anatase nanocrystals. High transparency, high photocatalytic activity, and superhydrophilicity were demonstrated for the anatase nanocrystals-precipitated coatings. [ABSTRACT FROM AUTHOR]

Proton conductive inorganic-organic hybrid films, which show high proton conductivity at temperatures higher than 100°C with low humidification, have been prepared from epoxycyclohexylethyltrimethoxysilane (EHTMS), 3-glycidoxypropyltrimethoxysilane, and orthophosphoric acid by the sol-gel method. Self-supporting, flexible, and brownish transparent films with a thickness ranging from 150 to 300 μm were obtained. Differential thermal analyses and thermogravimetric measurements revealed that the films were stable up to about 200°C. Ionic conductivity of the films increased with an increase in the content of phosphoric acid in the films. The films with a molar ratio of P/Si = 1.75 retained a high conductivity of about 6 × 10−4 S cm−1 even after holding for 150 h under 0.7% relative humidity at 130°C. The conductivity of the films increased with an increase in the relative humidity and was about 1 × 10−2 S cm−1 under 20% relative humidity at 130°C. [ABSTRACT FROM AUTHOR]

Formation process of convexly shaped oxide micropatterns using hydrophobic-hydrophilic patterned surface has been examined, and this technique was applied to several oxide thin films such as SnO2, ZrO2, TiO2 and Al2O3. Hydrophobic-hydrophilic patterned surfaces were prepared on glass substrates by selective UV irradiation through a photomask on double-layered films of a very thin TiO2 gel film as the underlayer and a hydrolyzed fluoroalkyltrimethoxysilane layer as the top layer. Precursor solutions were then spin-coated on the hydrophobic-hydrophilic patterns, and the coated substrates were dried at room temperature. The micropatterns of oxides were very difficult to be formed on the hydrophobic-hydrophilic patterned surfaces from metal-alkoxides as a precursor solution, but convexly shaped micropatterns were formed on the hydrophilic regions of the pattern when metal chlorides or oxychlorides were used as starting materials. This patterning technique potentially has a wide variety of applications such as fabrication of micro-optical components and finely patterned transparent electrodes. [ABSTRACT FROM AUTHOR]

Titania nanosheet-precipitated coatings have been prepared by treating SiO2-TiO2 gel films on glass substrates with hot water at 90°C under vibration. Longitudinal vibrations at about 6 Hz during the treatment enhanced the formation of titania nanosheet. The titania nanosheet consisted of several layers with a spacing of about 0.6 nm and was identified as hydrated titania with a lepidocrocite-type structure. The morphology of the titania nanosheet-precipitated coatings is probably achieved by lowering of the concentration of hydrolyzed titania species at the surface due to rapid water flow driven by the vibrations. The coatings were transparent in the visible range and showed high photocatalytic activity and antifogging property. [ABSTRACT FROM AUTHOR]

Transparent, superhydrophobic coating films have been prepared on polymer substrates at low temperatures through the sol-gel method. Al2O3 gel films were prepared on poly(ethylene terephthalate) substrates from Al(O- sec-C4H9)3 chemically modified with ethyl acetoacetate. A small roughness of about 20–50 nm was found to form on the surface of the Al2O3 gel films dried at room temperature and then immersed in hot water at 60°C. The electron diffraction measurements have shown that this roughened surface consists of pseudoboehmite nanocrystals. The coating of hydrolyzed fluoroalkyltrimethoxysilane on the Al2O3 gel films with the small roughness produced transparent, superhydrophobic films with contact angle for water larger than 150°. [ABSTRACT FROM AUTHOR]

Anatase nanocrystals were precipitated mainly at the surface of the silica-titania gel films with hot water treatment, whereas the addition of poly(ethylene glycol) (PEG) in the films led to the dispersion of anatase nanocrystals in the whole of the films after the treatment. Both films with and without PEG showed high photocatalytic activities for acetaldehyde, NO x and stearic acid in the gas-solid system, and for methylene blue and potassium iodide in the liquid-solid system. The addition of PEG improved the photocatalytic activities of the resultant films due to the smaller anatase crystallites and the porous film structure. The residual silica under-layer of the superficially anatase-precipitated films is expected to act as a protective one for an organic polymer substrate against the photocatalytic degradation. [ABSTRACT FROM AUTHOR]

Inorganic-organic hybrid coating films were prepared from various trifunctional silicon alkoxides with a C=C double bond in their organic components, such as vinyltriethoxysilane (VTES), allyltriethoxysilane (ATES) or trimethoxysilylpropylmethacrylate (TMSPM), and zirconium n-tetrapropoxide modified with methacrylic acid. UV light from a high-pressure mercury lamp was irradiated through a photomask on the hybrid films, and this irradiation increased refractive index and microhardness of the films and decreased solubility of the films in alcohol or alkaline solution. IR spectra of the coating films have shown that C=C bonds in these trifunctional silicon alkoxides were polymerized with the UV irradiation. Patterns with a width of about 10 μm and thickness of about 5–15 μm were formed by the etching of unirradiated region of the films. Since VTES and ATES have a shorter organic chain than TMSPM, the hybrid films prepared from VTES or ATES are expected to show small optical loss in the near-infrared region due to C—H bonds in their use as waveguides. [ABSTRACT FROM AUTHOR]

Copolymerized phenylsilsesquioxane-benzylsilsesquioxane particles were prepared from their corresponding organotriethoxysilanes by the sol-gel method. Transparent thick films of a few microns in thickness have been successfully prepared on glass substrates coated with indium tin oxide (ITO) by heat-treating the copolymerized particles which had been electrophoretically deposited on the substrates. The on-set temperature for thermal sintering of the copolymerized particles decreased from 150 to 50°C with increasing the benzylsilsesquioxane content. These on-set temperatures for thermal sintering of the particles were found to be higher by 10 to 50°C than the glass transition temperatures of the particles of the corresponding composition. The thermal sintering of the particles should occur due to a large decrease in viscosity of the particles at temperatures higher than the glass transition temperatures. The decrease in the on-set temperature with composition for thermal sintering as well as in the glass transition temperature of the particles can be related with the decreases in average molecular weight and in distribution of the molecular weight of the particles with an increase in the benzylsilsesquioxane content. [ABSTRACT FROM AUTHOR]

Anatase nanocrystals of 5 to 10 nm in diameter were formed in the silica-titania films by treatment with hot water. The formation of nanocrystals with hot water treatment was a unique phenomenon to the silica-titania system and the addition of organic polymers such as PEG was indispensable for the high dispersion of anatase nanocrystals in the films. The hydrolysis of Si—O—Ti bonds with hot water was considered to play an important role for the formation of anatase nanocrystals. The resultant films were transparent even after the formation of anatase nanocrystals. Acetaldehyde was photocatalytically decomposed into CO2 on the films which were subjected to a hot water treatment. The amounts of generated CO2 were twice of that of introduced acetaldehyde, indicating that the total acetaldehyde was completely decomposed to CO2. Anatase nanocrystals-dispersed films can be formed on various kinds of substrates including those with poor heat resistance such as organic polymers and organisms by this process, so that the substrates coated with the films are expected to be widely used for photocatalytic applications. [ABSTRACT FROM AUTHOR]

Porous silica films were obtained by a heat treatment of poly(ethyleneglycol)-containing gels for micro-patterning. Changes in porosity and the amount of adsorbed water with the heat treatment temperature in the silica films were evaluated from the refractive index of the films. The apparent refractive index of the silica films in an ambient atmosphere was much higher than the intrinsic refractive index of the film due to the large amount of adsorbed water in the films. The amount of adsorbed water in the films decreased with an increase in the heat treatment temperature and became almost zero after a heat treatment at 850°C. The decrease in the amount of adsorbed water in the films was caused by the decrease in silanol groups, which acted as the sites for water adsorption in the films. The drastic decreases in thickness and in porosity of the films at temperatures from 850 to 950°C occurred after the disappearance of silanol groups in the films. The densification of the films due to collapse of the pores at high temperatures should have resulted from the viscous flow of silica network. [ABSTRACT FROM AUTHOR]

We have successfully prepared transparent and porous anatase nanocrystals-dispersed films by treating the sol-gel derived TiO2-SiO2 films containing poly(ethylene glycol), PEG, with hot water. This process was done at temperatures lower than 100°C under atmospheric pressure, and thus anatase nanocrystals-dispersed films can be formed on various kinds of substrates including organic polymers with poor heat resistance. The changes in structure and composition of the TiO2-SiO2 gel films with hot water treatment were related to the formation process of anatase nanocrystals in the TiO2-SiO2 gel films with hot water treatment. The formation of anatase nanocrystals was found to proceed to hydrolysis of Si–O–Ti bonds and dissolution of SiO2 component. In addition, porous film structure formed by leaching of PEG with hot water treatment led to homogenous dispersion of anatase nonocrystals in the films. [ABSTRACT FROM AUTHOR]

Silica gels doped with several protonic acids such as HClO4, H2SO4 and H3PO4 have been prepared by the sol-gel method and totally solid electric double-layer capacitors have been successfully fabricated using the highly proton-conductive silica gels as an electrolyte and activated carbon powder (ACP) hybridized with the silica gels as a polarizable electrode. It was found that the addition of HClO4, which had the highest value of acid dissociation constant among these three acids, most effectively increased the proton conductivity of the resultant acid-doped silica gels. Tablets of the HClO4-doped silica gels exhibited conductivities as high as 10−5–10−2 S cm−1 at room temperature in dry N2 atmosphere. One of the capacitors fabricated using the protonic acid-doped silica gels had a capacitance of 44 F/(gram of total ACP in the capacitor), which was comparable to those of conventional capacitors using liquid electrolytes. [ABSTRACT FROM AUTHOR]

Highly proton-conductive elastic composites have been successfully prepared from H3PO4-doped silica gel and a styrene-ethylene-butylene-styrene (SEBS) block elastic copolymer. Ionic conductivities of the composites depended on the concentration of H3PO4 and the heat treatment temperature of the H3PO4-doped silica gel. It was found that H3PO4 added is present mainly as free orthophosphoric acid in the silica gel. The composite composed of H3PO4-doped silica gel with a molar ratio of H3PO4/SiO2 = 0.5 heat-treated at temperatures below 200°C and SEBS elastomer in 5 mass% showed a high conductivity of 10−5 S cm−1 at 25°C in an dry N2 atmosphere. The water adsorption during a storage in 25% relative humidity at room temperature for 1 day enhanced the ionic conductivities of composites by about one order of magnitude. Lower conductivities obtained in the composite with the H3PO4-doped silica gel heat-treated at 250°C for 1 h were due to the formation of crystalline Si3(PO4)4. The temperature dependence of conductivity of the composites was the Vogel-Tamman-Fulcher type, indicating that proton was transferred through a liquidlike phase formed in micropores of the H3PO4-doped silica gels. The temperature dependence of the modulus of the composite was similar to that of the SEBS elastomer. The thermoplastically deforming temperature of the composite was around 100°C, which was higher by 30°C than that of the SEBS elastomer. [ABSTRACT FROM AUTHOR]

This work reports on a novel controlled nanocomposite fabrication technique which is applicable for material design via a micro- and nano-assembly method. The principle is based on the use of electrostatic adsorption of the surface charge-modified particles via layer-by-layer assembly. The polarity and the zeta potential of the surface charge was controlled using polycation and polyanion, while the zeta potential strength was controlled via the number of alternating coating layers which was determined using zeta potential measurement. A systematic study was conducted to demonstrate the feasibility of composite material assembly via electrostatic adsorption using alumina (Al2O3) and silica (SiO2) composite as a study model, which was carried out as a function of surface zeta potential, surface coverage percentage, and processing time. The considerable potential of this technique for composite material design is also further demonstrated with controlled assembly involving different materials in various structural forms such as fiber, whisker, nanosheets, and even irregular-shaped foam-like structured urethane. The composite materials designed using this EA method possess good potentials to be utilized for various applications such as mechanical property control, composite ceramic films formation, selective laser sintering, and rechargeable metal-air battery. [ABSTRACT FROM AUTHOR]

Please note that in the original article [1] the name of the second author, Norio Hakiri, was erroneously ordered; the name was ordered with the given and family names the wrong way around, as 'Hakiri Norio'. [ABSTRACT FROM AUTHOR]

This work reports on the microstructure-controlled formation of interconnected carbon-layered Al2O3 ceramics using carbon nanoparticles (CNP)-alumina (Al2O3) composite particles. The Al2O3 micro-particles used in this study were obtained by granulation of nano-sized Al2O3 nanoparticles with an average diameter of 150 nm. Then, CNP-Al2O3 composite was fabricated using an electrostatic assembly method using the granulated Al2O3 and CNP. The decoration of CNP on the surface of granulated Al2O3 was investigated as a function of primary particle size and coverage percentage using a fixed amount of CNP. Notably, an interconnected layer of carbon particles at the interface of Al2O3 that resemble the grain boundaries was obtained. The mechanical properties of the samples obtained with different particle size and CNP coverage on Al2O3 particles were also investigated which presented the possibility to control the mechanical properties through microstructural design of composite ceramic materials. [ABSTRACT FROM AUTHOR]

Despite its unique properties, zinc oxide (ZnO) particles have limited usage in optoelectronic devices and biochemical sensors due to its relatively poor ultraviolet (UV) emission. In this research, the localized surface plasmon resonance (LSPR) effect of metal nanoparticles such as silver (Ag), aluminium (Al), copper (Cu) and iron (Fe) that were coupled with ZnO microrods was studied. The metal coupled ZnO microrods were synthesized by solution impregnated method. The metal nanoparticles were clearly observed deposited onto the surface of ZnO microrods using transmission electron microscope (TEM) and energy dispersive X-ray (EDX) mapping. The room temperature photoluminescence (RTPL) analysis of ZnO microrods coupled with Al, Ag, Fe showed remarkable improvement of UV emission and quenching of defect related emission. The intensity ratio (Iuv/Ivis) of ZnO microrods was 1.6 but was enhanced to 26.1, 4.4, and 4.0 by coupling of Al, Ag and Fe, respectively. However, when Cu was embedded onto ZnO microrods, the Iuv/Ivis of ZnO microrods was suppressed to 0.1. The photoluminescent mechanism of Al, Ag and Fe-ZnO particles was attributed to LSPR effect. In contrary, deposition of Cu onto ZnO microrods induced energy level in bandgap of ZnO, producing the visible light emission. [ABSTRACT FROM AUTHOR]