Search

Production and characterization of molybdenum disulfide (MoS2) and other transition metal dichalcogenide materials attract significant attention of scientific community due to pronounced two‐dimensional character of their electronic properties. Herein, MoS2 synthesis by chemical vapor deposition with gaseous hydrogen sulfide (H2S) containing thermally evaporated molybdenum (Mo) is presented. The films deposited onto silicon (Si) substrate consist of flake‐like crystallites of nanometer thickness assembled of parallel atomic layers oriented predominantly along a normal to the substrate surface. The dependence of film morphology on deposition time, substrate temperature, and precursor composition in gaseous phase is investigated. The Raman spectroscopy and electron microscopy analysis reveal the presence of mono‐ and bilayered structures in the film. Photoluminescence (PL) efficiency of the films is found to be increased in comparison with the monolayer MoS2 crystallites. The high PL efficiency in combination with the high spatial uniformity of the film materials makes them prospective for application in electronic and photonic industry. [ABSTRACT FROM AUTHOR]

The boosting efficiency of perovskite solar cells (PSCs) has evoked the interest in applying them in tandem structures, especially perovskite/silicon tandem solar cells. However, the tandem solar cells still face concerns about stability, upscaling, and cost‐effectiveness on the path to commercialization. Herein, an innovative tandem architecture based on the printable mesoscopic perovskite solar cells is proposed. By investigating the effects of indium tin oxide (ITO) particle size, annealing temperature, and dispersant on the performance of ITO mesoporous films, screen‐printable mesoscopic ITO electrode with an electron mobility of 7.5 cm2 V−1 s−1 and an average visible transmittance of over 80% is successfully obtained. The screen‐printed mesoporous titania, zirconia, and ITO are used as a scaffold and a semitransparent PSC with a champion power conversion efficiency of 9.38% is fabricated infiltrated with perovskites. Further, a perovskite/silicon tandem device which can remain stable for >720 h is demonstrated, highlighting the potential of screen‐printed inorganic scaffold structure in tandem photovoltaic technique. [ABSTRACT FROM AUTHOR]

Heterostructures formed by anatase nanotitania and bidimensional semiconducting materials are expected to become the next-generation photocatalytic materials with an extended operating range and higher performances. The capability of fabricating optically transparent photocatalytic thin films is also a highly demanded technological issue, and increasing the performances of such devices would significantly impact several applications, from self-cleaning surfaces to photovoltaic systems. To improve the performances of such devices, WS2/TiO2 heterostructures obtained by incorporating two-dimensional transition metal dichalcogenides layers into titania mesoporous ordered thin films have been fabricated. The self-assembly process has been carefully controlled to avoid disruption of the order during film fabrication. WS2 nanosheets of different sizes have been exfoliated by sonication and incorporated in the mesoporous films via one-pot processing. The WS2 nanosheets result as well-dispersed within the titania anatase mesoporous film that retains a mesoporous ordered structure. An enhanced photocatalytic response due to an interparticle electron transfer effect has been observed. The structural characterization of the heterostructure has revealed a tight interplay between the matrix and nanosheets rather than a simple additive co-catalyst effect. [ABSTRACT FROM AUTHOR]

Mesoporous materials possess unique structural characteristics, such as high surface area, large pore volume, and interconnected pore networks, which make them ideal candidates for photocatalysis. The objective of this review is to critically analyse the synthesis methods, characterization techniques, and photocatalytic performance of mesoporous titania films for photocatalysis. The article begins by providing a short overview of the chemical-physical processes involved in photocatalysis of titania. It highlights the need for efficient photocatalytic materials with enhanced surface area and light harvesting capabilities. Subsequently, the synthesis methods for creating mesoporous titania films are discussed, including sol-gel chemistry, templating approaches, and self-assembly techniques. Emphasis is placed on the control of pore size, distribution, and film thickness to optimize the photocatalytic performance. The influence of synthesis parameters on the film porosity, crystallinity, and surface area is examined in detail. Furthermore, the review highlights recent advancements in the field, including strategies to enhance the photocatalytic performance of mesoporous titania films through doping, surface modification, and heterostructure formation. These approaches aim to improve the light absorption, charge separation, and reactant accessibility, thus maximizing the utilization of solar energy for efficient photocatalysis. In conclusion, mesoporous titania films demonstrate great potential as effective photocatalytic materials. Their unique structural features, combined with proper synthesis and characterization, contribute to enhanced photocatalytic performance. Further research and development in this area may lead to the design and fabrication of advanced mesoporous titania films for a wide range of environmental and energy applications. [Display omitted] • Mesoporous ordered titania films show a remarkable photocatalytic activity. • Control of pore size, distribution, and film thickness optimize the photocatalytic performance. • Mesoporous titania films exhibit improved photocatalysis with respect to dense titania films. • Engineering of titania-based heterojunction enhances the light harvesting to the visible range. [ABSTRACT FROM AUTHOR]

In this study, an emphasis is put on vapor-sensitive Bragg stacks as an important class of optical sensors. All-niobia Bragg stacks were deposited by spin-coating of sol-gel Nb2O5 thin films alternated with mesoporous layers after proper design through optimization of operating wavelength and number of layers in the stack. Mesoporous Nb2O5 films with different morphology and identical structure were obtained using organic templates (Pluronics PE6200 and PE6800) and subsequent annealing. Transmittance measurements were performed as a detection method that offers technological simplicity and accuracy. It was demonstrated that stacks including PE6200 templated films exhibit higher sensitivity than stacks templated with PE6800. It was assumed and verified by computer-aided modelling of experimental data that mesoporous films prepared with addition of PE6200, although less porous, were more stable compared to those templated with PE6800, and did not collapse during the thermal treatment of the stacks. Furthermore, the reproducibility of optical response was studied by sorption and desorption cycles of acetone vapors. The suitability of all-niobia Bragg stacks for optical sensing of VOCs was discussed.

Composite self-supporting Al 2 O 3 -Fe films with different component ratios were obtained using sol-gel and selective reduction approaches. A comprehensive study of the composition, microstructure, as well as the textural, optical, catalytic and adsorption characteristics was carried out using XRD, Raman spectroscopy, HRTEM, AFM, N 2 physisorption and UV–vis absorption spectroscopy. The films have a mesoporous structure with a high specific surface area (up to 239 m2/g) and narrow pore size distribution. Iron species in the films predominantly exist in the form of metal (α-Fe) nanoparticles and disordered Fe 3 O 4. The most suitable sample for catalytic (H 2 O 2 decomposition) and Cr(VI) adsorption applications is the composite F 20 film due to a combination of its high textural characteristics, excellent catalytic, adsorption and magnetic properties. The Al 2 O 3 -Fe films can be easily separated from a liquid medium due to the rapid settling of large fragments or the possibility of magnetic separation. Image 1 • Mesoporous Al 2 O 3 -Fe films were prepared by sol-gel and selective reduction approaches. • Films have a high specific surface area and narrow pore size distribution. • Change of Fe content allows to vary the optical, catalytic and adsorption properties. • The most suitable sample (F 20) for catalysis and adsorption was identified. [ABSTRACT FROM AUTHOR]

Water compartmentalization in a two-dimensional (2D) configuration is a challenging and thriving field. Here, we form fluid-fluid structures called 2D vesicles in which aqueous solutions are encapsulated within small oil barriers into a mesoporous thin film that allows them to communicate with a surrounding aqueous environment through predefined paths. Each area in the 2D space can also be programmed to specifically achieve different chemical processes. The framework of these nanopore-supported 2D vesicles has exciting applications in advanced surface developments and multi-device technologies. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Introduction of colloidal Pt nanoparticles in ordered mesoporous carbon (OMC). • Carbonized PtNP/OMC coatings are homogeneous, conductive and show high surface area. • Nanoparticles retain size despite high temperatures due to pore confinement effects. • Coatings attach without binder which would block active sites or pores. • PtNP/OMC coatings reach two times higher activities in HER than commercial Pt/C. Abstract Platinum is the best catalyst known so far for the hydrogen evolution reaction (HER) in acidic environments, but it is also a scarce and expensive resource. Maximizing its performance per metal atom is essential in order to reduce costs. The deposition of small Pt nanoparticles (2–3 nm) onto electrically conductive, highly accessible and stable carbon supports leads to active catalysts. However, blocking of pores and active sites by Nafion, which acts as a binding species, reduces the catalytic activity. Moreover, inaccessible Pt located in micropores diminishes an efficient exploitation of the noble metal. We report a new synthesis approach to ordered mesoporous carbon (OMC) coatings with preformed Pt nanoparticles. The particles are exclusively located inside the mesopores. Furthermore, no Nafion binder is needed. As a consequence, the PtNP/OMC catalyst film outperforms Pt/C catalysts reported in literature particularly at high current densities. PtNP/OMC catalyst films with a geometric Pt loading of 1.6 µg Pt /cm2 achieve a current density of −100 mA/cm2 at an overpotential of ca. −70 mV. [ABSTRACT FROM AUTHOR]

Calixarenes have been drawing tremendous interest due to their special structure, superior properties and numerous applications. In this work, a novel adsorbent material, calix[4]arenes functionalized dual‐imprinted mesoporous film (DIMFs) for the simultaneous selective recovery of Li(I) and Rb(I), was prepared via surface ionic imprinting. Compared with ordinary adsorbent materials, the synthesis process of the films used a cheap bio‐template and did not require extra steps but significantly enhances adsorption properties. The morphology and structure of prepared DIMFs were characterized by scanning electron microscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT‐IR) and nitrogen adsorption–desorption measurements. Adsorption parameters (pH and temperature), adsorption kinetics and adsorption isotherms of the DIMFs were investigated by adsorption experiments. This novel adsorbent has inorganic–organic hybrid frameworks, high specific surface area and uniform pore size. The Langmuir and Freundlich isotherms, pseudo‐first‐order and pseudo‐second‐order kinetics of DIMFs were investigated; suggesting that the adsorption data well fits the Langmuir isotherm model, and the adsorption kinetics can be described by the pseudo‐second‐order kinetic model. In addition, dual‐imprinted mesoporous film exhibited superior selectivity for Li(I) and Rb(I). Cycle test demonstrated an outstanding of reusability, which appreciating their potential for industrial application. [ABSTRACT FROM AUTHOR]

Abstract: Creating CsPbBr3 perovskite nanocrystals with bright blue emission is challenging because their optical properties depend sensitively on structure. Growing perovskites in mesoporous templates bypasses some of these purification issues because the size of the nanocrystal is governed by the dimensions of the pores. Mesoporous silica consisting of aligned channels with tunable diameter can be easily synthesized and used as a template. When the perovskite solution evaporates and retreats, some of the liquid remains trapped in the interconnecting pores by discontinuous dewetting. The precursor crystallizes, generating stable ca. 3.1 nm blue‐emitting perovskite nanocrystals. The mesoporous template also serves as a protective barrier to preserve the optical properties of the CsPbBr3 from atmospheric conditions. Compared to the bulk crystals and the powder composite, the strong blue‐shift of the emission peak in the film is accompanied by a decrease in the longer lifetime component and an 8‐fold increase in the external quantum efficiency. [ABSTRACT FROM AUTHOR]

SiO 2 does not have magnetic elements; therefore, it behaves as a diamagnetic material with a possible paramagnetism due to oxygen vacancy defects. Incorporation of magnetic elements and pores into SiO 2 films can add an additional functionality to its dielectric and insulating properties. Herein we report the incorporation of Co element into the mesoporous framework of SiO 2 (Co–SiO 2) thin films through chemical sol-gel based-spin coating processes. The thus obtained Co–SiO 2 thin film exhibits transition in the magnetic properties, increase in the specific surface area and a decrease in the leakage current while maintaining better electric conductivity. For comparison, the bare mesoporous SiO 2 (m -SiO 2) films were prepared at identical conditions. Interestingly, a S-type shape on the isothermal magnetization measurements versus magnetic field (M vs. H) curves appeared at 5 K in case of the Co–SiO 2 films, and a paramagnetic behavior was observed at 50 K and above. The temperature-dependent magnetization (M vs. T) measurements of the Co–SiO 2 films also showed an increase of magnetization below 50 K. It is anticipated that Co substitutes Si although presence of the CoO and/or Co 3 O 4 phases cannot be completely ruled out. These results support the idea that a ferromagnetic-like transition takes place in the Co-doped SiO 2 films below 50 K due to Co doping. At the same time, a reduction in the leakage current density was determined in Co–SiO 2 , while maintaining better charge transfer in 1.0 M KOH for ion conducting devices. A successful doping of Co element in the framework of mesoporous SiO 2 thin films was demonstrated. The magnetization measurements support the idea that a ferromagnetic-like transition takes place in the Co-doped SiO 2 films below 50 K, while the bare SiO 2 did not show any magnetic properties. At the same time the leakage current was reduced by Co-doping with a slight increase in the dielectric constant (ε) due to Co doping, while maintaining better electric conductivity. [Display omitted] • Co-doped mesoporous SiO 2 (Co–SiO 2) thin films on Si were successfully prepared. • S-type shape on M vs H curves appeared at 5 K supports a ferromagnetic transition. • A paramagnetic behavior was observed at 50 K and above in the M vs. T curves. • The M vs T measurement also showed an increase of magnetization below 50 K. • The leakage current density was reduced, while maintaining better charge transfer. [ABSTRACT FROM AUTHOR]

We report the formation of mesoporous films consisting of SBA-15 particles grown directly onto substrates and their usage as catalysts in esterification of acetic acid and ethanol. The film thickness was altered between 80 nm and 750 nm by adding NH4F to the synthesis solution. The salt also affects the formation rate of the particles, and substrates must be added during the formation of the siliceous network in the solution. Various substrate functionalizations were tested and hydrophobic substrates are required for a successful film growth. We show that large surfaces (> 75 cm2), as well as 3D substrates, can be homogenously coated. Further, the films were functionalized, either with acetic acid through co-condensation, or by coating the films with a thin carbon layer through exposure to furfuryl alcohol fumes followed by carbonization and sulfonation with H2SO4. The carbon-coated film was shown to be an efficient catalyst in the esterification reaction with acetic acid and ethanol. Due to the short, accessible mesopores, chemical variability, and possibility to homogenously cover large, rough surfaces. the films have a large potential for usage in various applications such as catalysis, sensing, and drug delivery.

The precise control of primary reactions in solutions is one of the most significant steps for the nanoscale design of inorganic solids in multidisciplinary fields. However, further growth of the inorganic species to give bulkier species disturbs such designs. The surfactant-assisted synthesis of mesoporous materials is a good strategy for addressing such concerns because pores formed by supramolecularly mediated processes are surrounded by nanometer-sized continuous frameworks. Many experiments are generally conducted to optimize the reaction conditions for the synthesis of highly ordered mesostructures. Herein, to minimize such trial-and-error efforts, a new and practical concept is proposed for the precise design of porous materials. By adjusting the reactivity between bisphosphonates and metal sources through molecular design of the starting bisphosphonate compound, it was possible to synthesize mesoporous films with unique compositions by a surfactant-assisted approach. [ABSTRACT FROM AUTHOR]

Zirconium oxide (ZrO) is acquiring considerable attention of most of the research groups and leading to a large number of publications due to its unique properties, especially in the context of emerging trends in the third generation of solar cell research. ZrO films offer magnificent aspects related to physicochemical properties, and the properties are found to be dependent on synthesis methods. In the present review, various deposition techniques used to grow zirconium oxide thin films and their application to enhance the quantum efficiency of titanium oxide (TiO) based dye-sensitized solar cells (DSSCs) are discussed. Also, the modulated performances of DSSCs fabricated by growing the conformal ZrO insulating films to retard interfacial recombination dynamics on preformed TiO films are discussed. [ABSTRACT FROM AUTHOR]

Real-time measurements of fluidic phenomena inside nano/mesoporous films offer an alternative way to study fundamental processes, as well as to explore novel applications. Most current techniques use optical measurement methods or microgravimetric approaches. Here it is shown that a metal-oxide-semiconductor (MOS) capacitor can be used to detect fluidic transport inside mesoporous networks. The MOS stack, which consists of two contacts (Cu and silicon) separated by a supramolecularly templated mesoporous oxide film to form a MOS capacitor, detects fluid changes that can be quantified from an effective permittivity model of mesoporous structures interacting with a fluid. The device was used to monitor liquids infiltration and subsequent evaporation in both titania and silica mesoporous films. It was observed how the evaporation dynamics significantly depends on film characteristics and fluid properties. [ABSTRACT FROM AUTHOR]

In the present work, 2.4 nm gold nanoparticles (Au NPs) are uniformly dispersed on mesoporous titania thin films which are structurally tuned by controlling the calcination temperature. The gold content of the catalyst is as high as 27.8 wt %. To our knowledge, such a high loading of Au NPs with good dispersity has not been reported until now. Furthermore, the reaction rate of the gold particles is enhanced by one order of magnitude when supported on mesoporous titania compared to non-porous titania. This significant improvement can be explained by an increase in the diffusivity of the substrate due to the presence of mesopores, the resistance to agglomeration, and improved oxygen activation. [ABSTRACT FROM AUTHOR]

The precisely tailored refractive index of optical materials is the key to utilizing and manipulating light during its propagation through the matrix, thereby improving their application performances. In this paper, mesoporous metal fluoride films with engineered composition (MgF 2 :LaF 3 ) are demonstrated to achieve finely tunable refractive indices. These films are prepared using a precursor-derived one-step assembly approach via the simple mixing of precursor solutions (Mg(CF 3 OO) 2 and La(CF 3 OO) 3 ); then pores are formed simultaneously during solidification owing to the inherent instability of La(CF 3 OO) 3 . The mesoporous structures are realized through Mg(CF 3 OO) 2 and La(CF 3 OO) 3 ions, which interacted with each other based on their electrostatic forces, providing a wide range of refractive indices (from 1.37 to 1.16 at 633 nm). Furthermore, it is systematically several MgF 2(1-x) -LaF 3(x) layers with different compositions (x = 0.0, 0.3, and 0.5) to form the graded refractive index coating that is optically consecutive between the substrate and the air for broadband and omnidirectional antireflection. An average transmittance of ≈98.03% (400-1100 nm) is achieved with a peak transmittance of ≈99.04% (at 571 nm), and the average antireflectivity is maintained at ≈15.75% even at an incidence of light of 65° (400-850 nm)., (© 2023 The Authors. Small published by Wiley-VCH GmbH.)

The controlled growth of Ag nanoparticles into graphene-TiO mesoporous films has been triggered by hard X-ray exposure provided by a synchrotron storage ring. The kinetic process has been studied by UV-visible spectroscopy as a function of the X-ray dose and compared to the nanoparticle growth induced in a bare mesoporous titania matrix. The graphene layers act as a preferential nucleation sites, allowing a faster nucleation of the nanoparticles. Moreover, the growth of larger nanoparticles is also promoted as a function of the exposure dose. The combined bottom-up and top-down approach to fabricate nanocomposites porous films embedding both graphene and plasmonic nanoparticles is expected to be a fundamental tool for the design of new analytical platforms based on the enhancement of the Raman signals. Graphical Abstract: [ABSTRACT FROM AUTHOR]

The formation of highly ordered chiral organic/inorganic films with high density and long-range orientation is important in constructing chiral devices, such as broadband polarization devices, liquid-crystal displays, or negative-reflection materials. A feasible strategy is presented to fabricate three-dimensional mesostructured chiral DNA-silica assemblies into large-scale oriented arrangements. The highly ordered film was aligned by a mica crystal substrate with the bridging effect of suitable divalent metal ions, followed by the growth of the DNA-silica composite by bottom-up assembly with a 'quartet templating' method. This simple and effective route would perform well in the alignment and arrangement of highly charged biomolecules, such as polypeptides, proteins, viruses, and their inorganic assemblies, and furthermore could allow the fabrication of chiral optical materials with long-range ordering. [ABSTRACT FROM AUTHOR]

In the present study, as-prepared silver nanoparticles have been incorporated into SiO and TiO sols. The characterisation of the silver nanoparticles was performed through transmission electron microscopy, grazing X-ray diffraction, and UV-visible spectroscopy, before and after mixing with the different sols. Multilayer coatings doped with silver nanoparticles were also prepared by combining different compositions and analysed by TEM and GXRD. The photocatalytic activity was studied through the degradation of methyl orange in aqueous solution under UV light exposure. High photocatalytic efficiency was observed for all the multilayer coatings. The highest efficiency was obtained for the Ag-SiO/TiO mesoporous system that reached a degradation percentage of methyl orange up to 94 % after 2.5 h of irradiation, near the complete elimination of the pollutant. The mechanism that explains the high photocatalytic efficiency of this multilayer coating is associated with the high porosity of the mesoporous coatings and with the increase in the local electric field, associated with the effect of plasmon resonance surface produced for the presence of metallic silver nanoparticles in the SiO film. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Porous inorganic films of different materials and pore architecture: mesoporous γ-alumina, mesoporous yttria stabilized zirconia (YSZ), macroporous YSZ and macroporous/microporous zeolite silicalite, were synthesized by the sol–gel spin-coating or dip-coating methods on silicon wafers of different surface roughness. Their surface chemical properties, pore and phase structure, and surface roughness were studied by various surface characterization methods. The pore sizes of these films are determined by their primary particle size. All the films studied are hydrophilic due to the presence of hydroxyl groups on the external crystallite surface, and their hydrophilicity increases in the order: macroporous YSZ < mesoporous YSZ < silicalite < γ-alumina. The γ-alumina films have highly smooth surfaces, while mesoporous YSZ, macroporous YSZ and silicalite films have similar surface roughness much rougher than γ-alumina films. The surface roughness of these coated films does not depend on the coating method, surface roughness of the substrate, surface chemistry or pore structure of the films. It is more controlled by the shape and size of the primary particles and aggregates in the sol or suspension from which the films are obtained. [ABSTRACT FROM AUTHOR]

Polymeric sol–gel route has been used for the preparation of TiO2 and RE2O3–TiO2 (RE=Eu, Er) mesoporous thin films by evaporation induced self-assembly method using Si (100) as a substrate. The influence of the relative humidity (RH) on the preparation of the film has been studied being necessary to work under 40% RH in order to obtain homogeneous and transparent thin films. The films were annealed at different temperatures until 900°C/1h and the anatase crystallization and its crystal size evolution were followed by low angle X-ray diffraction. Neither the anatase–rutile transition nor the formation of other compounds was observed in the studied temperature range. Ellipsoporosimetry studies demonstrated that the thickness of the thin films did not change after calcination at 500°C, the porosity was constant until 700°C, the pore size increased and the specific surface area decreased with temperature. Moreover, the effect of the doping with Er3+ and Eu3+ was studied and a clear inhibition of the crystal growth and the sintering process was detected (by transmission electron and atomic force microscopy) when the doped films are compared with the undoped ones. Finally, Eu3+ and Er3+ f–f transitions were detected by PL measurements. [ABSTRACT FROM AUTHOR]

Abstract: The development of nanostructured electrodes for electrochemical biosensors is of significant interest for modern detection, portable devices, and enhanced performance. However, development of such sensors still remains challenging due to the time-consuming, detriment-to-nature, and costly modifications of both electrodes and enzymes. In this work, we report a simple one-step approach to fabricating high-performance, direct electron transfer (DET) based nanoporous enzyme-embedded electrodes by electrodeposition coupled with recent progress in potential-controlled interfacial surfactant assemblies. In contrast to those previously electrodeposited mesoporous materials that are not bioactive, we imparted the biofunctionality to electrodeposited mesoporous thin films by means of the amphiphilic phospholipid templates strongly interacting with enzymes. Thus, phospholipid-templated mesoporous ZnO films covalently inlaid with the pristine enzymes were prepared by simple one-step electrodeposition. We further demonstrate two examples of such hybrid film electrodes embedded with alcohol dehydrogenase (ADH) and glucose oxidase (GOx), which are effectively employed as electrochemical biosensors for amperometric sensing of ethanol and glucose without using any electron relays. The favorable mass transport and large contact surface area provided by nanopores play an important role in improving the performance of these two biosensors, such as excellent sensitivities, low detection limits, and fast response. The matrix mesoporous films acting as effective electronic bridges are responsible for DET between enzyme molecules and metal electrode. [Copyright &y& Elsevier]

Highlights: [•] Mesoporous NiO nanowall arrays are prepared by a hydrothermal method. [•] Mesoporous structure is favorable for fast ion/electron transfer. [•] Mesoporous NiO nanowall arrays show fast switching speed and high color contrast. [Copyright &y& Elsevier]

Fit to print: This work describes a novel vapor‐phase synthesis system to directly replicate mesoporous silica films from block copolymer films without phase transitions (see figure). [ABSTRACT FROM AUTHOR]

The synthesis of highly crystalline perovskite BaSnO3 nanoparticles for use as photoanode materials in dye-sensitized solar cells (DSSCs) is reported, and the photovoltaic properties of DSSCs based on BaSnO3 nanoparticles (BaSnO3 cells) are demonstrated. The resulting DSSCs exhibit remarkably rapid charge collection and a DSSC fabricated with a BaSnO3 film thickness of 43 µm leads to a high energy conversion efficiency of 5.2 %, which is one of the highest reported for ternary oxide-based DSSCs. More importantly, the BaSnO3 cells show superior charge collection in nanoparticle films compared to TiO2 cells and could offer a breakthrough in the efficiencies of DSSCs. [ABSTRACT FROM AUTHOR]

This paper quantifies the migration of silver contained within mesostructured hybrid silica films and mesoporous titania films under exposure to modulated light. This quantization allows to demonstrate that all of the initial silver salt can be concentrated and reduced in domains accumulating the higher photonic energy. Entirely reduced in the form of nanoparticles of few nanometers size embedded in the silica matrix, silver is then quite stable even under subsequent homogeneous exposures. It is also shown that thanks to the relatively slow nanoparticle growth, successive multiple exposures can be used to create complex 3D microstructures within silica films using a simple dual beam interferometer. In mesoporous titania films, the UV photo-growth of silver nanoparticles remains limited to the vicinity of the film interface because of the matrix absorption and cannot provide deep 3D patterns of silver nanoparticles. However, 2D refractive index patterns can be obtained under UV exposure, erased with visible light and updated thanks to a reversible photochromic behavior. In such films, opposite migration flows of silver species are proven under UV intensity gradient and homogeneous visible exposure. [ABSTRACT FROM AUTHOR]

Abstract: This study quantifies the highest perturbation encountered by the first layer of a TiO2 12 layers-mesoporous coating, which is submitted to a multistep calcination process. Besides, we propose an alternative thermal treatment in order to limit the degradation induced by repeated calcinations. This paper reports and compares the modifications in film thickness, surface area, anatase crystallite size and global crystallinity of films obtained from different thermal treatments. It defines the maximum crystal size compatible with the preservation of the mesoarchitecture initially induced by templating. Differences in microporosity and rate of crystallization are also discussed. [Copyright &y& Elsevier]

Abstract: The effect of zirconium dioxide addition on crystal structure of sol–gel TiO2 mesoporous films and powders has been investigated by means of Raman spectroscopy, X-Ray diffraction, and Atomic force microscopy. Zirconium incorporation (up to 30mol%) into TiO2 lattice resulted in the formation of Ti1−xZrxO2 solid solution with anatase structure for the binary powders has been proved. Appearance of tetragonal ZrO2 phase was observed for the samples with high zirconium content. [Copyright &y& Elsevier]

Mesoporous Thin Films (MTF) can be created by combining sol-gel synthesis, template self-assembly and chemical surface modification. A wide palette of inorganic (oxides, phosphates, carbon-based, etc.) and hybrid organic-inorganic frameworks with a variety of composition, pore sizes, and nanoscale, organic or biological functions located in the inorganic skeleton, pore surface or pore interior can be obtained. The properties of the functional pore systems are tuned by the pore size and geometry, wall composition and surface features. These MTF with interesting electronic and optical controlled features are indeed a ' nanofacility'. Well-defined monodisperse sized pores also act as nanoreactors, or nanocavities with controlled environment and behaviour. In the last years, the production of accessible MTF, in which either the pore surface or pore volume can be modified by organic functional groups or nanoparticles has been thoroughly explored. Each highly controlled MTF originated from a reproducible and modular synthesis is in itself a building block for more complex structures, presenting order at different length scales (molecular, mesoscopic, macroscopic), and novel properties derived thereof. Selected examples of optical and chemical behaviour of these multiscale materials are presented to illustrate these points. [ABSTRACT FROM AUTHOR]

Abstract: Porous TiO2 thin films have been prepared using an amphiphilic graft copolymer, i.e. poly(vinylidene fluoride-co-chlorotrifluoroethylene)-graft-poly(oxyethylene methacrylate) (P(VDF-co-CTFE)-g-POEM) as a structure-directing agent via the sol–gel process. The graft copolymer was synthesized via atom transfer radical polymerization using CTFE units as an initiating site and designed to have a hydrophobic P(VDF-co-CTFE) domain and a hydrophilic POEM domain. Fourier transform-infra red spectroscopy indicated that a hydrophilic titania precursor was selectively incorporated into hydrophilic POEM domains. In-situ formation and morphologies of porous TiO2 thin films were confirmed by ultraviolet–visible spectroscopy, X-ray diffraction, transmission electron microscopy and thermogravimetric analysis. The resultant porous TiO2 films with 10–25nm in size were used as a photoelectrode for solid-state dye-sensitized solar cells, exhibiting energy conversion efficiency of 2.8% at 100mW/cm2. [ABSTRACT FROM AUTHOR]

Abstract: ZnO:SiO2 films are intensively investigated for optical and electronic applications. Additionally, porous ZnO:SiO2 films are of great interest as catalyst and gas-sensing materials. The sol–gel method is an efficient and low-cost process for the deposition of meso- and microporous silica-based films. The present paper studies the effect of the withdrawal speed on the microstructure and optical properties of mesoporous ZnO:SiO2 films obtained by the sol–gel method. The morphology of the films was investigated by atomic force microscopy and the overall structure was studied by X-ray diffraction. The structure and size of the zinc oxide nanoparticles embedded in the silica matrix were investigated in more detail by transmission electron microscopy. These techniques showed ZnO:SiO2 films with crack-free mesoporous morphology and highly efficient embedding of ZnO nanoparticles with (100) preferred orientation. Furthermore, the optical transmittance (in the visible and near infrared regions) and the optical band gap value were observed to vary with withdrawal speed. It is shown that ZnO:SiO2 nanocomposites films which possess ZnO particles exhibiting a (100) orientation, with possible special applications in non-linear optics, could be prepared by the low-temperature crystallization sol–gel method. [ABSTRACT FROM AUTHOR]

Abstract: Topography at the nanoscale can lead to dramatic changes in the adhesion of cells to surfaces and their subsequent viability. For biological applications, including tissue engineering and cell-based sensing, the large internal surface area of ordered mesoporous carbons provides an opportunity for enhanced sensitivity and performance, but the mesostructure also affects the topography of the material. In this work, we probe the viability and adhesion of osteoblasts on ordered mesoporous materials with different morphologies and matrix chemistries. FDU-15 (hexagonal) and FDU-16 (cubic) films were processed at either 350°C (polymeric) or 800°C (carbon) to provide these different materials. For the films processed at 350°C, the cell adhesion was markedly improved on the mesoporous films in comparison to a dense film analog, consistent with many reports in the literature that nanostructuring of surfaces improves the viability and adhesion of osteoblasts. Conversely, osteoblast adhesion was reduced on the carbonized surfaces processed at 800°C when ordered mesopores were introduced, particularly for the cubic mesostructure (FDU-16). We attribute the decrease in cell adhesion to the propensity of the ordered mesoporous carbon films to sorb organics from aqueous solution, which could lead to removal of adhesion-promoting compounds at the film surface. These results suggest that cell viability on mesoporous polymer and carbon films can be controlled through simple changes in the pyrolysis temperature. [Copyright &y& Elsevier]

Abstract: A new sol–gel synthesis procedure of stable calcium copper titanate (CaCu3Ti4O12—CCTO) precursor sols for the fabrication of porous films was developed. The composition of the sol was selected in order to avoid the precipitation of undesired phases; ethanol was used as solvent, acetic acid as modifier and poly(ethyleneglycol) as a linker agent. Films deposited by spin-coating onto oxidized silicon substrates were annealed at 700°C. The main phase present in the samples, as detected by X-ray diffraction and Raman spectroscopy, was CaCu3Ti4O12. Scanning electron microscopy analysis showed that mesoporous structures, with thicknesses between 200 and 400nm, were developed as a result of the processing conditions. The films were tested regarding their sensibility towards oxygen and nitrogen at atmospheric pressure using working temperatures from 200 to 290°C. The samples exhibited n-type conductivity, high sensitivity and short response times. These characteristics indicate that CCTO mesoporous structures obtained by sol–gel are suitable for application in gas sensing. [Copyright &y& Elsevier]

Abstract: Large-size mesoporous thin films with a mixed titania-silica framework and an cubic-derived or worm-like mesostructure were obtained by combining sol-gel and macromolecular templating techniques. These materials presented accessible mesopores (20 to 25% pore volume), tunable refractive index and high molecular-scale mixing of both ions, as demonstrated by UV-Visible, FTIR and XANES spectroscopy. In addition, a composition effect in the catalytic reduction of silver was found, which permitted one to obtain homogeneous metal nanoparticle-mesoporous film nanocomposites with tuned plasmon position. [Copyright &y& Elsevier]

Abstract: Ethanol adsorption–desorption isotherms on well-organized mesoporous silica and titania films with hexagonal pores structure were studied by ellipsometric porosimetry. The mesopore volume was calculated from the change of the effective refractive index at the end points of the isotherm. An improved Derjaguin–Broekhoff–de Boer (IDBdB) model for cylindrical pores is proposed for the determination of the pore size. In this model, the disjoining pressure isotherms were obtained by measuring the thickness of the ethanol film on a non-porous film with the same chemical composition. This approach eliminates uncertainties related to the application of the statistical film thickness determined via t-plots in previous versions of the DBdB model. The deviation in the surface tension of ethanol in the mesopores from that of a flat interface was described by the Tolman parameter in the Gibbs–Tolman–Koening–Buff equation. A positive value of the Tolman parameter of 0.2nm was found from the fitting of the desorption branch of the isotherms to the experimental data obtained by Low Angle X-ray Diffraction (LA-XRD) and Transmission Electron Microscopy (TEM) measurements in the range of pore diameters between 2.1 and 8.3nm. [Copyright &y& Elsevier]

• Ti/SnO 2 –Sb 2 O 5 –IrO 2 are made using micelle templates of amphiphilic block-copolymers. • Template method produces anodes with mesoporous surfaces and enhanced active area. • The template-made anode is highly active towards the removal of reactive black 5-dye. • The template-made anode is 3-fold more stable than the Pechini-made anode. The mixed metal-oxide anode Ti/SnO 2 –Sb 2 O 5 –IrO 2 is a prominent candidate for the electro-oxidation of organic compounds in wastewater treatment systems. The catalytic activity of this material depends on its surface morphology, which strongly depends on the synthesis method used. Hence, here we manufactured innovative Ti/SnO 2 –Sb 2 O 5 –IrO 2 anodes using micelle templates made of amphiphilic block-copolymers and compared them with anodes made of the same composition using the Pechini method. Scanning electron microscopy, X-ray dispersive energy analysis, X-ray diffraction, cyclic voltammetry, and electrochemical impedance spectroscopy were used to characterise the morphology, composition, and electrochemical properties of the developed anodes. The "template method" produces anodes with mesoporous surfaces (11.0 ± 4 nm of pore diameter), which enhanced the electroactive area compared with the anodes made through the Pechini method. The templated anodes are more conductive than the Pechini-made ones and are more active for removing the reactive black 5-dye from 0.1 mol dm−3 Na 2 SO 4 aqueous solutions. The enhanced catalytic activity of the templated anode strongly increases with the addition of low concentrations of NaCl. The rate constants increase 3.9 and 4.7-fold when adding 200 ppm and 1168.8-ppm chloride, respectively. The templated anode removes 100% of the dye after only 15 min of electrolysis applying 20 mA cm−2 and leads to ∼50% mineralization after 60 min of oxidation. Notably, the template anode is 3-fold more stable in accelerated service lifetime tests than the Pechini-made anode. Therefore, our study shows that Ti/SnO 2 –Sb 2 O 5 –IrO 2 anodes made using the template method are highly promising for the electrochemical treatment of wastewater polluted with organic compounds. [ABSTRACT FROM AUTHOR]

We have prepared mesoporous composite Ni–Mo–O films (Ni–Mo–O MCFs) on conductive Au substrates via electrodeposition with the help of a soft template, and determined the optimal electrodeposition conditions of the films such as ethanol concentration, rotate speed, and current density. The composition of the films can be adjusted with the deposition current density and ethanol content to a Ni content within 50–75 wt.%. Mesoporosity is constantly present and homogeneously distributed on the films with a pore diameter about 5 nm–10 nm, and the film thickness is uniform at 200 nm. We propose a mechanism for the Ni–Mo–O MCFs formation, and evaluate the electrocatalytic activity for hydrogen evolution reaction (HER). Results show that the Ni–Mo–O MCFs display an improved active surface area and higher catalytic activity for HER, and excellent stability for over 70 h in 1 M KOH solution. The overpotential can reach a value of 222.8 mV at 10 mA cm−2 current density, with a Tafel slope of 141.66 mV dec−1, compared to bare substrate (558.57 mV at 10 mA cm−2). The improved electrocatalytic performance of Ni–Mo–O MCFs is attributed to the synergetic effect of the larger actual surface and the enhanced electrochemical activity of the films. • Mesoporous composite Ni–Mo–O films were prepared successfully via electrodeposition. • The size of mesopores can be effectively adjusted by optimal ethanol concentration. • The Ni–Mo–O MCF exhibit excellent HER activity and durability. [ABSTRACT FROM AUTHOR]

Abstract: Surface functionalised carbon nanoparticles of ca. 8nm diameter co-assemble with chitosan into stable thin film electrodes at glassy carbon surfaces. Robust electrodes for application in sensing or electrocatalysis are obtained in a simple solvent evaporation process. The ratio of chitosan binder backbone to carbon nanoparticle conductor determines the properties of the resulting films. Chitosan (a poly-d-glucosamine) has a dual effect (i) as the binder for the mesoporous carbon composite structure and (ii) as binding site for redox active probes. Physisorption due to the positively charged ammonium group (pK A ≈6.5) occurs, for example, with anionic indigo carmine (a reversible 2e−–2H+ reduction system in aqueous media). Chemisorption at the amine functionalities is demonstrated with 2-bromo-methyl-anthraquinone in acetonitrile (resulting in a reversible 2e−–2H+ anthraquinone reduction system in aqueous media). Redox processes within the carbon nanoparticle-chitosan films are studied and at sufficiently high scan rates diffusion of protons (buffer concentration depended) is shown to be rate limiting. The chemisorption process provides a much more stable interfacial redox system with a characteristic and stable pH response over a pH 2–12 range. Chemisorption and physisorption can be employed simultaneously in a complementary binding process. [Copyright &y& Elsevier]

Abstract: Mesoporous silica films covalently doped with hydrophobic disperse red chromophores have been prepared with a new pre-modification-direct synthesis route via a dip-coating technique using P123 surfactant as the structure-directing agent under acidic conditions. The disperse red chromophores were pre-modified with hydrophilic alkoxylsilanes and then hydrolyzed and co-condensed with tetraethylorthosilicate to form mesostructured hybrid films. The effect of aging time of starting sols and chromophore concentrations on the mesostructures and dye aggregations were investigated. Non-mesostructured films were also prepared as a reference. In the mesostructured hybrid films, the hydrophilic silane groups of the modified disperse red were covalently linked onto the pore surface while the hydrophobic disperse red chromophores monomerically dispersed in the pore spaces of the films rather than restricted within the silica walls due to its hydrophobic nature. [Copyright &y& Elsevier]

Abstract: Mesoporous films of TiO2 were prepared by a sol–gel procedure using a Pluronic® block copolymer and the dip-coating technique. The film thickness was controlled by changing the film withdrawal rate and by repetitive coatings. The amount of dye molecules adsorbed onto the mesoporous film depends on the dye properties, with thionine and methylene blue being more strongly adsorbed than rhodamine B, methyl orange and methyl red. The photocatalytic efficiency of the degradation of these dyes strongly depends on their respective degradation mechanism. It was found that the optimum efficiency is achieved when the target molecule is adsorbed only to some extent thus enabling its decomposition directly by the attack of holes. On the other hand, secondary oxidizing species such as O2 − and HO2 likely even OHrucial role in the oxidation mechanism, which is particularly evident in the case of methylene red. Higher concentrations of adsorbed species to be degraded may even be detrimental as found when thionine was employed as the model compound. [Copyright &y& Elsevier]