Multifunctional high-reflective and antireflective layer systems with easy-to-clean properties

High-reflective (HR) and even more antireflective (AR) layer systems are in use for widespread applications. Multifunctional layer systems providing high optical functionality with an easy-to-clean or a self-cleaning behaviour would be preferable for many applications to avoid soiling of the surface. In this paper, the feasibility of fabrication by highly productive pulse magnetron sputtering in an in-line coating plant is investigated. Easy-to-clean properties are achieved by a top layer of photocatalytic and photoinduced hydrophilic TiO₂.Multifunctional HR layer systems were successfully deposited on glass and polyethylene terephthalate (PET) substrates at a low deposition temperature of 150 °C, demonstrating the possibility of coating certain polymer materials. Double-sided multifunctional AR layer systems with a single-sided photoinduced hydrophilic TiO₂ top coating have a resulting reflectivity of about 3% and transmittance of about 97% in the visible range of light.     

Deposition of photocatalytic TiO2 layers by pulse magnetron sputtering and by plasma-activated evaporation

Crystalline TiO₂ thin films, especially layers with predominantly anatase phase, exhibit photocatalytic activities resulting in photoinduced hydrophilic, self-cleaning and antifogging properties. In this paper, a comparison of the photocatalytic properties of layers deposited with two different PVD techniques is given.On one hand, a reactive pulse magnetron sputtering (PMS) system has been used to obtain TiO₂ films at dynamic deposition rates from 8 to 50 nm m/min. On the other hand, TiO₂ layers were deposited by reactive electron beam evaporation at very high deposition rates between 500 and 1000 nm m/min. An additional spotless arc discharge (Spotless arc Activated Deposition—SAD process) was used for plasma activation to improve layer properties. Photoinduced hydrophilicity was investigated by measuring the decrease of the water contact angle during UV-A irradiation.     

CuO/TiO_2异质多孔纳米结构的制备及其光催化性能

以Cu(OH)_2纳米棒阵列为前驱体,钛酸四丁酯为钛源,采用外向包覆合成法,利用Cu(OH)_2自身热分解产生的微量水分子与负载在其表面的钛酸四丁酯缓慢反应,制备了CuO/TiO_2异质多孔纳米结构,并研究了产物对罗丹明B(RhB)的光催化降解性能。结果表明,得到的产物薄膜为直径2~4μm的微孔组成的多孔纳米结构,微孔的孔壁由直径500nm左右的纳米棒组装而成。产物CuO/TiO_2异质多孔纳米结构比纯TiO_2纳米结构对RhB有更好的光催化降解性能,这主要是由两方面的原因引起的:一方面,CuO/TiO_2异质多孔纳米结构具有更好的吸附性能和更大的比表面积;另一方面,产物CuO/TiO_2为异质复合纳米结构,异质结的存在能有效地降低光生电子空穴对的复合,从而提高产物的光催化降解效果。     

Ni掺杂TiO2薄膜的甩胶喷雾热分解法制备和自清洁性能的研究

以钛酸丁脂（Ti（C4H9O）4）为先驱体,硝酸镍（NiNO3）为掺杂物,采用甩胶喷雾热分解方法在玻璃衬底上制备出了镍掺杂TiO2自清洁薄膜,通过扫描电镜（SEM）、X射线衍射（XRD）、紫外-可见透射光谱（UV-Vis）、光催化和亲水性能测定等手段对样品进行分析,结果表明,500r/min为理想衬底转速,350℃是理想的衬底沉积温度,500℃是理想的样品退火温度。随着镍掺杂量的不断增加,TiO2薄膜的亲水性能也越好,当镍掺杂量达2%-3%时,TiO2薄膜的亲水性能达到最好。     

高效光催化降解气相苯纳米TiO2微球的制备EI北大核心CSCD

以四氯化钛为钛源,尿素为沉淀剂前驱物,硫酸钠为分散剂,利用水热法在水-醇体系中制备出纳米TiO2微球。运用X射线衍射、电子显微镜、N2吸附-脱附和紫外-可见光谱等手段表征样品的结构和性质,并考察了水热温度对纳米TiO2微球结构及光催化降解气相苯活性的影响。结果表明,此类微球由纳米颗粒组成,且比表面积大,介孔结构明显,光吸收出现明显的“蓝移”。光催化结果显示,微球具有很高的光催化活性,尤其是180℃下制备的微球仅用20min将苯完全去除,但生成CO2的量仍随时间有所增加,表明微球的强吸附性能促进其光催化降解过程,且矿化率高达5.5,是P25(2.7)的2倍。     

Study of the adhesion of Staphylococcus aureus to coated glass substrates

The adhesion of Staphylococcus aureus was studied using a selection of laboratory-prepared and commercially available coated glass substrates using a simple methodology. Substrates were examined by scanning electron microscopy, atomic force microscopy and water droplet contact angles. It was found that microbial adhesion was independent of surface roughness, when this was of a lower magnitude than microbial size. It was also found that microbial adhesion was greater for hydrophilic surfaces than for hydrophobic ones, but that on a photoinduced superhydrophilic surface, microbes were more spread out—a potential benefit for more effective photocatalytic disinfection. It is suggested that hydrophobic and photoinduced superhydrophilic surface coatings both have potential as a means of reducing microbial fouling of surfaces.     

Visible light photocatalytic H₂-production activity of CuS/ZnS porous nanosheets based on photoinduced interfacial charge transfer

Visible light photocatalytic H(2) production through water splitting is of great importance for its potential application in converting solar energy into chemical energy. In this study, a novel visible-light-driven photocatalyst was designed based on photoinduced interfacial charge transfer (IFCT) through surface modification of ZnS porous nanosheets by CuS. CuS/ZnS porous nanosheet photocatalysts were prepared by a simple hydrothermal and cation exchange reaction between preformed ZnS(en)(0.5) nanosheets and Cu(NO(3))(2). Even without a Pt cocatalyst, the as-prepared CuS/ZnS porous nanosheets reach a high H(2)-production rate of 4147 μmol h(-1) g(-1) at CuS loading content of 2 mol % and an apparent quantum efficiency of 20% at 420 nm. This high visible light photocatalytic H(2)-production activity is due to the IFCT from the valence band of ZnS to CuS, which causes the reduction of partial CuS to Cu(2)S and thus enhances H(2)-production activity. This work not only shows a possibility for substituting low-cost CuS for noble metals in the photocatalytic H(2) production but also for the first time exhibits a facile method for enhancing H(2)-production activity by photoinduced IFCT.     

Synthesis of cactus-like zincoxysulfide (ZnOxS1−x) nanostructures assisted by a task-specific ionic liquid and their photocatalytic activities

A hydrothermal method has been employed to prepare cactus-like zincoxysulfide ZnO_xS_1?x nanostructures with the assistance of a dicationic task-specific ionic liquid (TSIL), [mim]{(CH)₂}₃[imm](SCN)₂. To the best of our knowledge, this is the first time that this TSIL with the SCN anion has been used in place of conventional reagents as a source of S to prepare a ZnO_xS_1?x nanostructure. The photocatalytic activities of the ZnO_xS_1?x nanostructures have been compared using UV and visible lights. BET results showed that the surface areas and photocatalytic activities of cactus-like zincoxysulfide ZnO_xS_1?x nanostructures were higher than those of other samples. ZnO_xS_1?x nanostructures with cactus-like morphology exhibited a significant enhancement of photocatalytic activity toward the degradation of methyl orange (MO) as compared to other samples, as revealed by photoluminescence measurements. This could be attributed to enhanced oxygen vacancies and crystallite defects formed as a result of substitution of S^2? in the lattice of ZnO.     

Solar-light photoamperometric and photocatalytic properties of quasi-transparent TiO2 nanoporous thin films

Transparent photocatalytic surfaces are of ever increasing importance for many applications on self-cleaning windows and tiles in everyday applications. Here, we report the formation and photocatalytic testing of a quasi-transparent thin and nanoporous titania films deposited on glass plates. Sputtered Ti thin films were anodized in fluoride-ion-containing neutral electrolytes to form optically semitransparent nanoporous films, which transformed to be completely transparent after thermal annealing. The nanoporous films were studied at different stages, such as before and after anodization, as well as after thermal annealing using scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-vis and Raman spectroscopy. It was observed that anodization at 20 V of high-temperature deposited titanium films resulted in regular nanopore films with pore diameters of 30 nm. Structural investigations on the transparent nanopore arrays reveal the presence of anatase phase TiO(2) even after annealing at 500 °C, which was confirmed by XRD and Raman spectroscopy measurements. The solar-light induced photocatalytic decomposition of stearic acid and photoconductivity characteristics of these nanoporous thin films are also presented.     

Mechanically durable superhydrophobic surfaces

Development of durable non-wetting surfaces is hindered by the fragility of the microscopic roughness features that are necessary for superhydrophobicity. Mechanical wear on superhydrophobic surfaces usually shows as increased sticking of water, leading to loss of non-wettability. Increased wear resistance has been demonstrated by exploiting hierarchical roughness where nanoscale roughness is protected to some degree by large scale features, and avoiding the use of hydrophilic bulk materials is shown to help prevent the formation of hydrophilic defects as a result of wear. Additionally, self-healing hydrophobic layers and roughness patterns have been suggested and demonstrated. Nevertheless, mechanical contact not only causes damage to roughness patterns but also surface contamination, which shortens the lifetime of superhydrophobic surfaces in spite of the self-cleaning effect. The use of photocatalytic effect and reduced electric resistance have been suggested to prevent the accumulation of surface contaminants. Resistance to organic contaminants is more challenging, however, oleophobic surface patterns which are non-wetting to organic liquids have been demonstrated. While the fragility of superhydrophobic surfaces currently limits their applicability, development of mechanically durable surfaces will enable a wide range of new applications in the future.     

Photocatalytic activity and stability of TiO2/ZnAl layered double hydroxide based coatings on mortar substrates

The surface properties and photocatalytic activity of the cement and pozzolanic mortar samples coated with TiO₂/ZnAl layered double hydroxides were studied with the intention to design suitable protective, hydrophilic coatings. In order to underline the existing correlation between the water uptake characteristics and the surface features, the coated mortars were subjected to water absorption test by capillarity, to photo-induced surface water absorption test and to photo-induced hydrophilicity test by contact angle measurements. The self-cleaning behavior of the mortar systems was evaluated by monitoring the photocatalytic rhodamine B removal efficiency in correlation with the development of photo-induced surface hydrophilicity. The coating durability was assessed towards the weathering effect of rain (essential for the coating self-cleaning properties). The positive result of the coating deposition was the improvement of photocatalytic activity, photo-induced hydrophilicity and the decrease of mortar systems surface roughness. The study revealed that the developed coating promotes self-cleaning effect.     

Simple template-free solution route for the synthesis of Ni(SO(4))(0.3)(OH)(1.4) nanobelts and their thermal degradation

Nanobelts of nickel hydroxyl sulfate have been prepared on a large scale via a simple template-free hydrothermal reaction on the basis of a complex [Ni(NH(3))(6)](2+) formed with Ni(2+) and ammonia in an ethanol-water solution. The as-synthesized nanobelts were single crystals, with several tens of microns in length and 50-150?nm in width. The nanobelts were enclosed by top surfaces (100) and side surfaces (001) and their growth direction was parallel to [010]. The function of aqueous ammonia and ethanol was discussed. Furthermore, nanostructures of a mixture of crystralline NiO and amorphous nickel sulfate with various morphologies, such as nanobelts, porous nanobelts, and nanoparticles, were obtained by the thermal treatment of the as-synthesized Ni(SO(4))(0.3)(OH)(1.4) nanobelts at different temperatures.     

Preparation of Au-BiVO4 heterogeneous nanostructures as highly efficient visible-light photocatalysts

Au-BiVO(4) heterogeneous nanostructures have been successfully prepared through in situ growth of gold nanoparticles on BiVO(4) microtubes and nanosheets via a cysteine-linking strategy. The experimental results reveal that these Au-BiVO(4) heterogeneous nanostructures exhibit much higher visible-light photocatalytic activities than the individual BiVO(4) microtubes and nanosheets for both dye degradation and water oxidation. The enhanced photocatalytic efficiencies are attributed to the charge transfer from BiVO(4) to the attached gold nanoparticles as well as their surface plasmon resonance (SPR) absorption. These new heteronanostructures are expected to show considerable potential applications in solar-driven wastewater treatment and water splitting.     

Synthesis and photocatalytic characterization of porous cuprous oxide octahedra

Porous cuprous oxide octahedra with a mean diameter of 1 μm have been successfully prepared with high yield via a hydrothermal reduction process at a low temperature. The growth mechanism and the influences of the poly(vinylpyrrolidone) (PVP) and citric acid have been discussed. And then, the samples were used as photocatalytic in the degradation of methyl red (MR). Thanks to the 3D architecture of the product, the photocatalytic performance has been significantly improved. We believe that the present work will open up to systematically explore ways to fabricate porous nanostructures and thus find use in a variety of applications.     

(Metal yolk)/(porous ceria shell) nanostructures for high-performance plasmonic photocatalysis under visible light

We describe a route to the preparation of (metal yolk)/(porous ceria shell) nanostructures through the heterogeneous growth of ceria on porous metal nanoparticles followed by the calcination-induced shrinkage of the nanoparticles. The approach allows for the control of the ceria shell thickness, the metal yolk composition and size, which is difficult to realize through common templating approaches. The yolk/shell nanostructures with monometallic Pt and bimetallic PtAg yolks featuring plasmon-induced broadband light absorption in the visible region are rationally designed and constructed. The superior photocatalytic activities of the obtained nanostructures are demonstrated by the selective oxidation of benzyl alcohol under visible light. The excellent activities are ascribed to the synergistic effects of the metal yolk and the ceria shell on the light absorption, electron-hole separation and efficient mass transfer. Our synthesis of the (metal yolk)/(porous ceria shell) nanostructures points out a way to the creation of sophisticated heteronanostructures for high-performance photocatalysis.

     

Au纳米粒子表面等离子共振效应(SPR)增强Au/Bi2WO6异质纳米结构的光催化活性

采用水热-光还原法在三维Bi₂WO₆的二级结构纳米片表面原位沉积Au纳米粒子(Au NPs), 成功获得了具有可见光响应活性的Au/Bi₂WO₆异质光催化剂, 并借助XRD、FE-SEM、HR-TEM、XPS和 UV-Vis-DRS谱等手段对其物相组成、形貌和光吸收特性进行表征, 以罗丹明B(RhB)和苯酚为模型污染物对其光催化性能进行研究。实验结果表明, 与纯Bi₂WO₆相比, 所得Au/Bi₂WO₆异质纳米结构对染料降解具有较高的活性, 当Au负载量为1.5at%时, Au/Bi₂WO₆复合催化剂的催化活性最好, 其光催化降解RhB和苯酚的表观速率常数分别是纯Bi₂WO₆的1.5倍和2.2倍。自由基捕获实验表明, 光生空穴(h⁺)和∙O₂^-是RhB在Au/Bi₂WO₆催化材料上光催化降解的主要活性物种。机理分析表明, Au/Bi₂WO₆活性增强归因于光生电子从Bi₂WO₆的导带向AuNPs表面迁移, 降低光生电子-空穴对的复合率, 同时, Au NPs 的等离子共振效应(SPR)拓展了催化剂在可见光区的响应范围, 从而显著提高了Au/Bi₂WO₆异质光催化的剂活性。Au NPs修饰Bi₂WO₆异质催化剂光太阳能驱动在污水处理方面具有潜在应用。     

Facile preparation of porous carbon nitride for visible light photocatalytic reduction and oxidation applications

In this work, we have employed melamine, cyanuric acid and thymine to fabricate triazine-based carbon nitrides (CNs) by supramolecular approach. The resultant CNs possess large specific surface area, hierarchical porous structure, better light absorption capacity and high separation rate of photoinduced carriers. Then, the photocatalytic reduction and oxidation performance has been evaluated. The obtained CNs exhibit enhanced photocatalytic reduction performance on water splitting to H₂, the largest hydrogen evolution rate can reach 8466.3 μmol g^?1 h^?1, which is 81.9 times as high as that of bulk CN. Simultaneously, the porous CNs show excellent photocatalytic reduction ability on the conversion of CO₂ to H₂, CO and CH₄. Of particular interest is that they have high selectivity for CO. It’s worth noting that the porous CNs also possess outstanding photocatalytic oxidation ability on high concentration nitric oxide (NO), and the highest NO conversion rate can reach 79.3% under visible light. The enhanced photocatalytic performance for the multifunctional porous CN can be ascribed to the synergic effect of large specific surface area, strong light absorption capacity and fast separation of photoinduced electron–hole pairs. Finally, the photocatalytic reduction and oxidation mechanism of the porous CN is also proposed and discussed.     

Wettability control of a transparent substrate using ZnO nanorods

This paper presents a simple way of controlling the wettability of a structured surface with ZnO nanorods on a transparent substrate. A combination of ZnO nanostructures and stearic acid was used to create superhydrophobic surfaces with the potential properties of being self-cleaning, waterproof, and antifog. ZnO nanorods were uniformly covered on glass substrates through a simple hydrothermal method with varying growth time which affects the surface morphology. When a substrate is dipped into 10 mM stearic acid in ethanol for 24 h, chemisorption of the stearic acid takes place on the ZnO nanorod surface, after which the hydrophilic ZnO nanorod surfaces are modified into hydrophobic ones. The contact angle of a water droplet on this superhydrophobic ZnO nanorod surface increased from 110 degrees to 150 degrees depending on the growth time (from 3 to 6 h) with a high transparency of above 60%. In addition, the water contact angle can be made to as low as 27 degrees after exposing the substrate to 10-mW/cm2 UV for 1 h.     

Micro and nano-texturization of intermetallic oxide alloys by a single anodization step: preparation of artificial self-cleaning surfaces

Micro- and nanostructures of Ti-γCu (γ = 0, 30, 50, 70, and 100 wt %) intermetallic alloys were produced through a single anodization step. It was found that the original alloy composition influences the final oxide morphology obtained after anodization which presented formation of a microstructure with nanotubes, nanoparticles or nanopillars on the surface. Pure Ti and Cu oxide metals and their alloys presented hydrophilic or superhydrophilic properties immediately after anodization. When the anodized pure metal and/or Ti-γCu surfaces were functionalized with trimethoxypropylsilane (TPMSi), by dipping and coating with a thin perfluorinated layer, the treated substrates became in all cases superhydrophobic (water contact angles in the range of 152-166°), showing excellent self-cleaning properties with hysteresis below 3°. These results can be explained by a combination of nanomicro morphologies with low surface energy compounds in the topmost monolayers. The decrease in hysteresis was associated with a higher M-OH bond concentration on the anodized surfaces, which allowed for more complete TMPSi coating coverage. This study also indicates that easy and effective fabrication of superhydrophobic surfaces in pure metals and alloys is possible without involving traditional multistep processes.     

光催化自清洁陶瓷的制备及其特性

制备了表面镀有光催化剂薄膜的自清洁陶瓷,并利用ＸＲＤ、ＡＥＳ和原位光催化反应方法等研究了其光催化降解油酸和灭菌的特性,考察了热处理条件和膜厚度等光催化膜制备与反应条件对自清洁陶瓷光催化活性的影响．研究结果表明,灭菌效果和油酸光降解速度取决于负载光催化膜的晶相组成、晶粒大小及其比表面积．