Control of Optical Properties of Thin Films Doped with Au Fine Particles by the Sol-Gel Method

We have developed tinted glasses with thin films doped with Au particles by the sol-gel method for automotive windows. Pink-colored glasses are mass-produced. The observed color is from absorption due to surface plasma resonance of Au particles. The squeeze-out of fine Au particles out of gel films was restrained by an organic additive. The index of the matrix was adjusted by the mixing ratio of TiO₂ (refractive index n = 2.20) to SiO₂ (n = 1.46). The absorption of Au particles is more intense with the higher index of the matrix, and its peak varies from 530 nm for n = 1.46 to 630 nm for n = 2.20, which yields a transmission color from pink to blue. The combination of the color of the glass substrate and the absorption by the Au particles in the thin films with various indices yields a variety of tinted glasses such as pink, orange, blue, blue-green and gray.     

Control of optical properties of gel-derived oxide coating films containing fine metal particles

Control of the optical properties of gel-derived oxide films containing fine metal particles is described. The duration of the aging of Si(OC₂H₅)₄-derived sols and the amount of water for hydrolyzing Si(OC₂H₅)₄ were found to greatly affect the size and the shape of Au particles formed in the silica matrix, and accordingly the optical absorption of the Au/SiO₂ composite films. Employing dielectric media with high refractive indices like TiO₂ was shown to shift the absorption peak of Au particles to longer wavelengths. Pd/TiO₂ and Pt/TiO₂ composite films showed absorption in the visible region.     

Sol-Gel Preparation of Coating Films Containing Noble Metal Colloids

Coating films containing Au, Ag, Pt and Pd metal colloids have been prepared by sol-gel processing. It is shown that for oxide films the temperature where the metal particles are precipitated by heating in air depends on metal species: 200°C for Au, 600°C for Ag, 800°C for Pt and 1000°C for Pd. The use of reducing atmosphere lowers the temperature for formation of noble metal colloids. This procedure can be used for direct formation of metal colloids from metal ions in the film as well as reduction of oxide particles to metal particles in the film. For an organic-inorganic matrix, noble metal colloids are precipitated by thermal reduction or photo-reduction. Thermal reduction occurs as a result of reduction by decomposing organic matter. Photo-reduction occurs as a result of UV irradiation.     

金属β－二酮化合物用于MOCVD法生长铁电氧化物薄膜

对用于MOCVD法生长铁电氧化物薄膜的金属β－二酮化合物的制备、结构及性质进行了评述，对它们在生长铁电薄膜中的应用现状进行了介绍，并对它们的应用前景作了展望。     

MoO3, WO3 Single and Binary Oxide Prepared by Sol-Gel Method for Gas Sensing Applications

MoO₃, WO₃ single and Mo/W binary compounds at different Mo/W atomic percentages were deposited by sol-gel spin coating technique on Si/Si₃N₄ substrates provided with Pt interdigital electrodes and annealed at 450°C for 1 h. Films were characterized by SEM, grazing incidence XRD and XPS techniques. Electrical responses to different gases were obtained by exposing the films to 30 ppm CO and 1 ppm NO₂. Increasing the Mo/W content the selectivity to NO₂ is enhanced. Gas responses resulted to be influenced by the Mo/W weight ratio, films morphology and amount of crystalline phases.     

Preparation of coating films doped with gold metal particles from methyltriethoxysilane-tetraethoxysilane solutions

Silica coating films of 0.5–0.7 m in thickness doped with gold metal particles were prepared by heating gel coating films obtained from solutions of acid-catalyzed methyltriethoxysilane (MTES) and tetraethoxysilane (TEOS) mixture containing chlorauric acid tetrahydrate. Transparent coating films with deep blue, red, and purple colors were obtained. Changes in size and shape of the gold particles with the MTES content were observed. Lower MTES contents gave bigger and non-spherical particles, while higher MTES contents produced smaller and more spherical particles with a more uniform size distribution. The effect of heat-treatment temeprature on the shape, size, and size distribution of the metallic gold particles was also studied.On leave from Dipartimento di Ingegneria Meccanica, Sezione Materiali, Universita di Padova, Via Marzolo, 9-35131 Padova, Italy.     

Atomic Force Microscopic Studies of Porous TiO2 Thin Films Prepared by the Sol-Gel Method

Porous titanium dioxide thin films were prepared from alkoxide solutions with and without polyethylene glycol (PEG) by the sol-gel method on soda-lime glass. The effects of PEG addition to the precursor solution on the microstructure and roughness of the resultant thin films were investigated by atomic force microscopy (AFM). It was found that TiO₂ films prepared from the precursor solution without PEG had granular microstructure and flat texture, and was composed of about 100 nm spherical particles. With an increase in the times of coating cycles, the roughness of films decreased and the size of TiO₂ particles increased. On the other hand, the larger the amount and molecular weight of the added PEG in precursor solutions, the larger the diameter and the depth of pores in the resultant films on the decomposition of PEG during heat-treatment. The surface of the films was also rougher, and fewer pores were produced during heat-treatment. The mechanism of porous structure formation in the TiO₂ films was explained using the principle of spinodal phase separation.     

Probing the Catalytic Activity of Reduced Graphene Oxide Decorated with Au Nanoparticles Triggered by Visible Light

Hybrid materials in which reduced graphene oxide (rGO) is decorated with Au nanoparticles (rGO–Au NPs) were obtained by the in situ reduction of GO and AuCl₄^?_(aq) by ascorbic acid. On laser excitation, rGO could be oxidized as a result of the surface plasmon resonance (SPR) excitation in the Au NPs, which generates activated O₂ through the transfer of SPR‐excited hot electrons to O₂ molecules adsorbed from air. The SPR‐mediated catalytic oxidation of p‐aminothiophenol (PATP) to p,p′‐dimercaptoazobenzene (DMAB) was then employed as a model reaction to probe the effect of rGO as a support for Au NPs on their SPR‐mediated catalytic activities. The increased conversion of PATP to DMAB relative to individual Au NPs indicated that charge‐transfer processes from rGO to Au took place and contributed to improved SPR‐mediated activity. Since the transfer of electrons from Au to adsorbed O₂ molecules is the crucial step for PATP oxidation, in addition to the SPR‐excited hot electrons of Au NPs, the transfer of electrons from rGO to Au contributed to increasing the electron density of Au above the Fermi level and thus the Au‐to‐O₂ charge‐transfer process.     

Novel Cellulose Derivatives Containing Metal (Cu,Fe, Ni) Oxide Nanoparticles as Eco-Friendly Corrosion Inhibitors for C-Steel in Acidic Chloride Solutions

Novel environmentally-friendly corrosion inhibitors based on primary aminated modified cellulose (PAC) containing nano-oxide of some metals (MONPs), for instance iron oxide nanoparticles (Fe₃O₄NPs), copper oxide nanoparticles (CuONPs), and nickel oxide nanoparticles (NiONPs), were successfully synthesized. The as-prepared PAC/MONPs nanocomposites were categorized using Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and selected area diffraction pattern (SAED) techniques. The data from spectroscopy indicated that successful formation of PAC/MONPs nanocomposites, as well as the TEM images, declared the synthesized PAC/Fe₃O₄NPs, PAC/CuONPs, and PAC/NiONPs with regular distribution with particle size diameters of 10, 23 and 43 nm, respectively. The protection performance of the as-prepared PAC and PAC/MONPs nanocomposites on the corrosion of C-steel in molar HCl was studied by the electrochemical and weight-loss approaches. The outcomes confirmed that the protection power increased with a rise in the [inhibitor]. The protection efficiency reached 88.1, 93.2, 96.1 and 98.6% with 250 ppm of PAC/CuONP, PAC/Fe₃O₄NPs, and PAC/NiONPs, respectively. PAC and all PAC/MONPs nanocomposites worked as mixed-kind inhibitors and their adsorption on the C-steel interface followed the isotherm Langmuir model. The findings were reinforced by FT-IR, FE-SEM and EDX analyses.     

溶剂化金属原子浸渍法制备高分散Au/TiO2低温CO氧化催化剂

用溶剂化金属原子浸渍法制备了不同金含量的高分散Ａｕ／ＴｉＯ２催化剂,ＸＲＤ和ＴＥＭ测定结果表明,随着金含量的增加,金颗粒度增大,但直径都在１．８～３．５ｎｍ范围内,ＸＰＳ研究表明上于金属态,Ａｕ／ＴｉＯ２在低温下就显示出较高的ＣＯ知性,３２３Ｋ时ＣＯ的转化率可达到１００％,金颗粒度为１．８ｎｍ的Ａｕ／ＴｉＯ２催化剂活性最高。     

Macroporous Morphology of the Titania Films Prepared by a Sol-Gel Dip-Coating Method from the System Containing Poly(Ethylene Glycol). I. Effect of Humidity

The influence of humidity upon the macroporous morphology of the titania films has been studied for a sol-gel dip-coating system containing poly(ethylene glycol) (PEG). The water adsorption from the ambient atmosphere modifies the polycondensation rate of TiO2 oligomer and the phase separation rate between the TiO2-PEG complex and solvent mixture, and greatly varies the macroscopic morphology of the resultant TiO2 film.     

织构气体扩散层表面氢氧燃料电池阴极超低Pt载量催化层的磁控溅射法制备

采用磁控溅射技术在具有织构结构的气体扩散层(GDL)表面制备了可应用于氢氧质子交换膜燃料电池的超低Pt载量阴极催化层, 并通过SEM、 轮廓仪和XRD等测试方法表征了GDL及其载Pt后的形貌和物相, 利用XPS分析溅射Pt的化学价态, 使用电池测试台表征其电池性能. 测试结果表明, 磁控溅射法在GDL表面沉积的Pt催化层载量可控且分布均匀; 与商业GDL对比, Pt在织构GDL表面具有更大的可附着面积. 电池性能测试结果显示, 当Pt载量为0.04 mg/cm²时, 以织构GDL作基材的样品质量比功率高达26.25 kW/g Pt, 远大于商业GDL作基材时的17.76 kW/g Pt, 也大于同等Pt载量下商业Pt/C催化剂的24.00 kW/g Pt.     

Macroporous Morphology of the Titania Films Prepared by a Sol-Gel Dip-Coating Method from the System Containing Poly(Ethylene Glycol). II. Effect of Solution Composition

The influences of water and alkoxide concentrations, as well as the relative humidity upon the macroporous morphology of the titania (TiO2) films have been studied for a sol-gel dip-coating system containing poly(ethylene glycol) (PEG). The distribution of resultant morphology against the withdrawal speed and relative humidity is varied significantly by mainly modifying the polycondensation and phase separation processes during the dipping operation, even by the small change in starting composition of the dipping solution.     

Low‐Temperature Atomic Layer Deposition of Copper Metal Thin Films: Self‐Limiting Surface Reaction of Copper Dimethylamino‐2‐propoxide with Diethylzinc

A uniform, conformal, pure copper metal thin film was grown at very low substrate temperatures (100–120 °C) on Si(100) substrates by atomic layer deposition involving the ligand exchange of [Cu(OCHMeCH₂NMe₂)₂] with Et₂Zn (see scheme). Patterned copper thin films of Cu nanotubes (diameter 150 nm, length 12 μm) were fabricated.

     

Au-TiO2/Ti Hybrid Coating as a Liquid and Gas Diffusion Layer with Improved Performance and Stability in Proton Exchange Membrane Water Electrolyzer

The liquid and gas diffusion layer is a key component of proton exchange membrane water electrolyzer (PEMWE), and its interfacial contact resistance (ICR) and corrosion resistance have a great impact on the performance and durability of PEMWE. In this work, a novel hybrid coating with Au contacts discontinuously embedded in a titanium oxidized layer was constructed on a Ti felt via facile electrochemical metallizing and followed by a pre-oxidization process. The physicochemical characterizations, such as scanning electron microscopy, energy dispersive spectrometer, and X-ray diffraction results confirmed that the distribution and morphology of the Au contacts could be regulated with the electrical pulse time, and a hybrid coating (Au-TiO₂/Ti) was eventually achieved after the long-term stability test under anode environment. At the compaction force of 140 N cm⁻², the ICR was reduced from 19.7 mΩ cm² of the P-Ti to 4.2 mΩ cm² of the Au-TiO₂/Ti. The corrosion current density at 1.8 V (RHE) is 0.689 μA cm⁻². Both the ICR and corrosion resistance results showed that the prepared protective coating could provide comparable ICR and corrosion resistance to a dense Au coating.     

Morphology,Structure, and Dynamics of Pentacene Thin Films and Their Nanocomposites with [C2C1im][NTf2] and [C2C1im][OTF] Ionic Liquids

In this study, a homogeneous thin film growth of pentacene onto indium tin oxide (ITO) coated glass surfaces is explored using a high-resolution and reproducible vapor deposition methodology. Moreover, vacuum thermal evaporation of ionic liquids (ILs) ([C₂C₁im][NTf₂] and [C₂C₁im][OTF]) onto ITO, gold/palladium (AuPd) and pentacene surfaces were performed. A greater wettability behavior of ILs is observed for surfaces containing AuPd. Sequential and simultaneous depositions of ILs and pentacene were explored. Simultaneous depositions lead to the formation of nanocomposites films, consisting of IL micro- and nanodroplets covered by pentacene layers. Plasma surface treatment was used to induce the ILs droplets coalescence and explore the dynamics and phase separation of the nanocomposites. The [C₂C₁im][OTF] droplets were found to be completely covered with pentacene, which suggests a great affinity between cation-anion pairs and the aromatic moiety. Pentacene films and their nanocomposites with ILs exhibit a typical optical band gap of E_gap=1.77 eV, indicating that the nanocomposite phase domains are large enough to behavior as the bulk.     

Non‐Fouling Character of Poly[2‐(methacryloyloxy)ethyl Phosphorylcholine]‐Modified Gold Surfaces Fabricated by the ‘Grafting to’ Method: Comparison of its Protein Resistance with Poly(ethylene glycol)‐Modified Gold Surfaces

Poly[2‐(methacryloyloxy)ethyl phosphorylcholine] ‐modified gold surfaces, which have been newly prepared by a ‘grafting to’ method using a series of monosulfanyl‐terminated PMPC, are characterized by protein adsorption experiments based on surface plasmon resonance spectroscopy and ellipsometry measurements. The extent of BSA adsorption on PMPC‐modified surfaces was systematically reduced for thicker PMPC layers, thus the number of MPC units on the gold surface appears to be an important factor for the excellent protein resistance offered by PMPC‐modified gold surfaces fabricated by the ‘grafting to’ method, which is sharp contrast to that of PEG tethered chains.

     

Speciation and detection of arsenic in aqueous samples: A review of recent progress in non-atomic spectrometric methods

Inorganic arsenic (As) displays extreme toxicity and is a class A human carcinogen. It is of interest to both analytical chemists and environmental scientists. Facile and sensitive determination of As and knowledge of the speciation of forms of As in aqueous samples are vitally important. Nearly every nation has relevant official regulations on permissible limits of drinking water As content. The size of the literature on As is therefore formidable. The heart of this review consists of two tables: one is a compilation of principal official documents and major review articles, including the toxicology and chemistry of As. This includes comprehensive official compendia on As speciation, sample treatment, recommended procedures for the determination of As in specific sample matrices with specific analytical instrument(s), procedures for multi-element (including As) speciation and analysis, and prior comprehensive reviews on arsenic analysis. The second table focuses on the recent literature (2005–2013, the coverage for 2013 is incomplete) on As measurement in aqueous matrices. Recent As speciation and analysis methods based on spectrometric and electrochemical methods, inductively coupled plasma-mass spectrometry, neutron activation analysis and biosensors are summarized. We have deliberately excluded atomic optical spectrometric techniques (atomic absorption, atomic fluorescence, inductively coupled plasma-optical emission spectrometry) not because they are not important (in fact the majority of arsenic determinations are possibly carried out by one of these techniques) but because these methods are sufficiently mature and little meaningful innovation has been made beyond what is in the officially prescribed compendia (which are included) and recent reviews are available.