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Temperature-induced sorption in porous materials is a well-known process. What is more challenging is to determine how the rate at which temperature is varied affects these processes. To address this question, we introduce a methodology called ‘‘cyclic thermo-ellipsometry’’ to explore the thermo-kinetics of vapor physisorption in metal–organic framework films. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) nanorods were coated on glass substrates and used as photocatalysts to evaluate the kinetic behavior of three different aromatic structures: i) single aromatic ring (phenol), ii) poly-aromatic ring (methylene blue), and iii) complex macromolecule (humic acid). The kinetics of all the tested molecules obey a pseudo-first-order model regardless of their initial concentrations. The apparent rate constants are largely controlled by the bond dissociation energy and the number of oxidation steps in each organic molecule. For instance, methylene blue presents the weakest dissociation bond energy and the highest degradation rate constant compared to humic acid and phenol. [Display omitted] • ZnO nanorods were deposited on glass substrates by hydrothermal growth method. • Photocatalytic tests were carried-out on methylene blue, humic acid & phenol. • Degradation mechanisms over ZnO photocatalysts follow pseudo-first-order kinetics. • Oxidative pathways are directly governed by the chemical structure of each molecule. • Apparent rate constants are depend on bond dissociation energies & oxidative steps. [ABSTRACT FROM AUTHOR]

A new type of acidic macrocellular and mesoporous silica–alumina foam is obtained via a one pot alkaline sol–gel route coupled with a concentrated emulsion-based templating technique. The mixed oxide monolith exhibits high surface acidity, translating into excellent performance in the acid-catalyzed dehydration of bioethanol to ethene. [ABSTRACT FROM AUTHOR]

Abstract: The complete understanding of the properties of a material goes in close relationship with a correct description of their structure. This is particularly true for mesoporous silica that exhibits different shapes and sizes of the porous framework as well as different degrees of crosslinking of the silica network itself. These variations can affect drastically the specific properties of these materials as well as their hydrothermal resistance. Hydrothermal resistance and adsorption properties are governed by the surface structure, but the later parameter is not frequently studied because it can be difficult to characterize. Therefore a simple parameter such as surface roughness could be helpful in relating the properties of materials with their surface structure. The direct determination of surface roughness is impossible, but it has been demonstrated that a single mathematical parameter, the surface fractal dimension Ds, can be related within a certain limit with surface roughness. Here we demonstrate using nitrogen adsorption data that a correlation can be drawn between the values of the surface fractal dimension Ds used as a gauge of the surface roughness and the structural evolution of a series of mesoporous silicas. Among the different adsorption models for obtaining Ds that are available nowadays, we selected the one proposed by Avnir and Jaroniec. We demonstrate in this report that there exists a real correlation between the evolution of Ds, when applied to a series of samples prepared under different synthesis conditions, with the evolution of their structure and properties. By example, this study allowed us to link the range of hydrothermal resistance of different mesoporous silicas (e.g. the HMS, MSU, MCM, SBA families of silicas) with their surface roughness. Moreover, we found that HMS silica, a very resistant material toward hydrothermal treatment, exhibits actually the lowest surface roughness. We could demonstrate too how different synthesis parameters such as temperature, can modify this surface roughness, hence the final properties of the mesoporous silica. Finally, we show that this method can even be applied to water ellipsoporometry and help to follow the crystallization of thin layers of metal oxide. Bearing in mind that Ds is a parameter that can readily be determined using the existing software – based on different models – associated with most commercial adsorption equipment, we urge the broader use of the Ds parameter for the structural characterization of surface roughness in mesoporous materials and metal oxide thin layers. [Copyright &y& Elsevier]

Academic and industrial research groups are currently working to obtain high-quality transparent ultralow-refractive-index and ultralow-dielectric-constant thin films, as they are important for designing smart devices and systems for microoptics and microelectronics (for example, multilayer structures, optical resonators, photonic crystals, Cu interconnects, insulating layers and so on). Here, we report a robust and simple procedure to prepare highly porous and resistant semicrystalline magnesium oxyfluoride thin films through liquid deposition followed by a flash and short thermal treatment. These films are water insensitive, mechanically resistant (E=1 GPa), exhibit high optical quality and have an ultralow refractive index (n700 nm=1.09) and an ultralow dielectric constant (k100 kHz=1.6) which are required for the above-mentioned applications. Moreover, the process used to prepare these nanomaterials is well suited for industrial production on larger surfaces. [ABSTRACT FROM AUTHOR]

Abstract: Thickness, refractive index n and extinction coefficient k of eriochrome cyanine R (ECR) dye doped mesostructured silica film (ECRMSSF) dip-coated on silicon wafers without prior removal of surfactant have been determined in the visible range of the spectrum by spectroscopic-ellipsometry (SE). ECRMSSF was used as sensing detection layer of Cu2+ in aqueous solutions of known pH. The dependence of optical parameters on the pH range of the aqueous phase (pH=6–8) was investigated. The detection reversibility of ECRMSSF was demonstrated. An electron paramagnetic resonance spectrum demonstrated the complexation of Cu2+ by the entrapped ECR. [Copyright &y& Elsevier]

Abstract: We report the singular filtration properties of an ultrafiltration membrane made with mesoporous silica that exhibits cylindrical pores aligned mostly normal to the support. This membrane supported on tubular commercial macroporous alumina supports was prepared by the interfacial growth mechanism between stable silica–surfactant hybrid micelles made of the association of silica oligomers with polyethyleneoxide-based (PEO) surfactants and sodium fluoride, a well-known silica condensation catalyst [Boissière et al., An ultrafiltration membrane made with mesoporous MSU-X silica, Chem. Mater. 15 (2003) 460–463]. It appears that the combined effect of the silica nature of the membrane, whose surface charge can be easily adjusted by changing the pH and the non-connected cylindrical shape of the pores provides a new behavior in the retention properties, as proved by the filtration of polyoxyethylene polymers (PEO) with different molecular weights. Depending on the filtration conditions, a rejection rate of 80% and a steep cut-off at 2000Da can be obtained or, on the reverse, polymers three times bigger than the pore diameter can diffuse through the membrane. This new filtration mechanism, which opens up new modes of separation modes, is explained in the light of both topology of the porous network and pH-dependent interactions between PEO polymers and silica porous media. [Copyright &y& Elsevier]

Abstract: We present a general review on the synthesis of mesoporous silica obtained with nonionic surfactants and bloc-copolymers as templates. This silica, referred as MSU silica, was obtained by a two-step process that led to the formation of stable hybrid micelles after a first stage of assembling between silica and surfactants, followed by the fluoride-catalyzed condensation of silica. This process allows some unique features: the final pore size can be adjusted with some synthesis parameters such as temperature or amount of catalyst, the particle shape is spherical and in the micrometric range, different shapes and nanostructures can be achieved, including hexagonal-like frameworks. Finally, we demonstrate how an accurate control of the synthesis itself may allow us to adapt this synthesis for applications dedicated to separation processes, including liquid filtration of HPLC chromatography. To cite this article: É. Prouzet, C. Boissière, C. R. Chimie 8 (2005). [Copyright &y& Elsevier]

Innovative strategies to produce well-defined nanoparticles and other nanostructures such as nanofibres, quantum wells and mesoporous materials have revitalized materials science for the potential benefit to society. Here, we report a controlled process, involving soft-chemistry-based deposition, template-assisted mesostructured growth, and tuned annealing conditions that allows the preparation of ordered mesoporous crystalline networks and mesostructured nano-island single layers, composed of multicationic metal oxides having perovskite, tetragonal or ilmenite structures. This strategy to obtain meso-organized multi-metal-oxide nanocrystalline films (M3NF) bridges the gap between conventional mesoporous materials and the remarkable properties of crystalline ternary or quaternary metallic oxides. Nanocrystalline mesoporous films with controlled wall thickness (10–20 nm) of dielectric SrTiO3, photoactive MgTa2O6 or ferromagnetic semi-conducting CoxTi1−xO2−x were prepared by evaporation-induced self-assembly (EISA) using a specially designed non-ionic block-copolymer template. A tuned thermal treatment of the mesoporous films permits the transfer of the wall structure into nanocrystallites, with all tectonic units being tightly incorporated into mechanically stable ordered tri- or bidimensional nanocrystalline networks. This methodology should allow multifunctionalization, miniaturization and integration during development of devices such as smart sensors and actuators, better-performing photocatalysts, and fast electrochromic devices. On the other hand, organized arrays of dispersed ferromagnetic or ferroelectric nanoparticles are promising materials for spintronics and for cheap, non-volatile 'flash' memories. [ABSTRACT FROM AUTHOR]

When drying a colloidal solution, cracks appear in the resulting colloidal film. In certain cases, spontaneous order is observed, and cracks form arrays of periodic patterns. Although this phenomenon might be envisioned as a patterning method, overcoming practical challenges is necessary to transform it into a technological tool for microfabrication. This study explores various technological aspects aimed at leveraging the self‐assembly of cracks as a scalable microfabrication tool for large‐scale device production. Through a series of analyses, including time‐resolved Grazing‐Incidence Small‐Angle X‐Ray Scattering (GISAXS), it is offered novel insights into controlling the crack self‐ordering mechanism, minimizing defects, and implementing strategies for large‐scale patterning and pattern transfer. The process proves to be surprisingly robust, maintaining its efficacy with the same colloidal solution even after two years. By introducing biphasic dip‐coating, large‐scale crack patterns up to 100 cm2, while preserving their periodicity and ordering is achieved. As a proof of concept, the use of crack‐patterned colloidal films as masks for fabricating metallic sub‐micrometer objects, that serve as transparent electrodes with adjustable transparency and conductivity is showcased. Overall, this method presents significant advantages over conventional lithography, being cost‐effective, versatile, environmentally friendly, and scalable, thereby offering new perspectives for diverse applications requiring cost‐effective and large‐scale patterning. [ABSTRACT FROM AUTHOR]

ZnO is an effective photocatalyst applied to the degradation of organic dyes in aqueous media. In this study, the UV-light and sunlight-driven photocatalytic activities of ZnO nanoparticles are evaluated. A handheld Lovibond photometer was purposefully calibrated in order to monitor the dye removal in outdoor conditions. The effect of ZnO defect states, i.e., the presence of zinc and oxygen defects on the photocatalytic activity was probed for two types of dyes: fuchsin and methylene blue. Three morphologies of ZnO nanoparticles were deliberately selected, i.e., spherical, facetted and a mix of spherical and facetted, ascertained via transmission electron microscopy. Aqueous and non-aqueous sol-gel routes were applied to their synthesis in order to tailor their size, morphology and defect states. Raman spectroscopy demonstrated that the spherical nanoparticles contained a high amount of oxygen vacancies and zinc interstitials. Photoluminescence spectroscopy revealed that the facetted nanoparticles harbored zinc vacancies in addition to oxygen vacancies. A mechanism for dye degradation based on the possible surface defects in facetted nanoparticles is proposed in this work. The reusability of these nanoparticles for five cycles of dye degradation was also analyzed. More specifically, facetted ZnO nanoparticles tend to exhibit higher efficiencies and reusability than spherical nanoparticles. [ABSTRACT FROM AUTHOR]

Aerosol processing is long known and implemented industrially to obtain various types of divided materials and nanomaterials. The atomisation of a liquid solution or suspension produces a mist of aerosol droplets which can then be transformed via a diversity of processes including spray-drying, spray pyrolysis, flame spray pyrolysis, thermal decomposition, micronisation, gas atomisation, etc. The attractive technical features of these aerosol processes make them highly interesting for the continuous, large scale, and tailored production of heterogeneous catalysts. Indeed, during aerosol processing, each liquid droplet undergoes well-controlled physical and chemical transformations, allowing for example to dry and aggregate pre-existing solid particles or to synthesise new micro- or nanoparticles from mixtures of molecular or colloidal precursors. In the last two decades, more advanced reactive aerosol processes have emerged as innovative means to synthesise tailored-made nanomaterials with tunable surface properties, textures, compositions, etc. In particular, the “aerosol-assisted sol–gel” process (AASG) has demonstrated tremendous potential for the preparation of high-performance heterogeneous catalysts. The method is mainly based on the low-cost, scalable, and environmentally benign sol–gel chemistry process, often coupled with the evaporation-induced self-assembly (EISA) concept. It allows producing micronic or submicronic, inorganic or hybrid organic–inorganic particles bearing tuneable and calibrated porous structures at different scales. In addition, pre-formed nanoparticles can be easily incorporated or formed in a “one-pot” bottom-up approach within the porous inorganic or hybrid spheres produced by such spray drying method. Thus, multifunctional catalysts with tailored catalytic activities can be prepared in a relatively simple way. This account is an overview of aerosol processed heterogeneous catalysts which demonstrated interesting performance in various relevant chemical reactions like isomerisation, hydrogenation, olefin metathesis, pollutant total oxidation, selective oxidation, CO2 methanation, etc. A short survey of patents and industrial applications is also presented. Our objective is to demonstrate the tremendous possibilities offered by the coupling between bottom up synthesis routes and these aerosol processing technologies which will most probably represent a major route of innovation in the mushrooming field of catalyst preparation research. [ABSTRACT FROM AUTHOR]

In this work, a soft-lithographic approach to fabricate submicrometer metal organic framework (MOF)-based 2D photonic structures is described. Nanometric zeolitic imidazole framework material ZIF-8 (zinc) is chosen as the sensible MOF material because of its chemical stability and its vapor selective adsorption properties. Two different systems are fabricated: nanopatterned colloidal ZIF-8 homo- and ZIF-8/TiO2 heterostructures. Several features (stripes, squares, etc.) with dimensions of 200 nm are replicated on different substrates such as silicon, flexible plastics, and even aluminum cans, over relatively large surfaces (up to 1 cm2). In addition, the use of these photonic MOF-heterostructures as very low-cost sensing platforms compatible with smartphone technology is demonstrated. This method relies on the evaluation of the change in diffraction efficiency of the photonic MOF-patterns, induced by the MOF refractive index variation, which is simply detected by a charge coupled device (CCD) camera, as those integrated in smartphones, without need for complex optical instrumentations for transduction data processing. Performances of the sensors are first evaluated using isopropyl alcohol adsorption/desorption cycling as a model case. In addition, a 'real' environmental issue is tackled. Selective detection of styrene in presence of interfering water is demonstrated at concentrations below the human permissible exposure limit. In situ ellispometric analyses are also carried out in order to confirm the sensor performances and to propose a mechanism for styrene uptake into the nanoMOFs. [ABSTRACT FROM AUTHOR]

• A single liquid crystalline lamellar membrane of a glucolipid microbial biosurfactant can be supported onto a flat substrate. • Deposition is performed by dip-coating, an easy-to-implement physical method. • Dip-coating allows control of a single molecular layer (2.8 ± 1.0 nm) of the supported membrane. • The supported membrane is entirely glycosylated and crack-free on the support, from nm -to- cm scale. The development of supported glycosylated lipid layers is an important trend in the field of glyconanomaterials for their interest in understanding sugar-sugar and protein–sugar interactions, these being at the core of cellular, bacterial or viral adhesion. The conventional self-assembled monolayer (SAM) approach generally requires a thiolated glycoconjugate and a gold substrate. In this work, we show how glycolipid amphiphiles of natural origin, commonly known as microbial biosurfactants, can be easily deposited onto a substrate. Spontaneously produced by microorganisms but lacking a thiol group, one can take advantage of their self-assembly properties to prepare homogeneous supported lipid monolayers (SLM). We then choose a saturated glucolipid, G-C18:0, which forms a colloidal lamellar phase under diluted conditions. The lamellae can then be deposited onto a substrate (silicon, gold) using a physical method (dip coating). Dip coating is preferred over more classical deposition methods (Langmuir-Blodgett-LB-, vesicle fusion or spin-coating) because of its versatility, compatibility with aqueous solutions and robust control of the thickness below 10 nm. Defect-free glycosylated SLM from a microbial biosurfactant are then easily developed. A combination of ellipsometry, fluorescence microscopy, atomic force microscopy and infrared nanospectroscopy (AFMIR) show that the glycosylated SLM are defect-free, have a thickness of 2.8 ± 1.0 nm and they are highly homogeneous at scales going from the nm to cm. [ABSTRACT FROM AUTHOR]

A one pot synthesis of alumina supported faceted nickel nanoparticles is carried out following a simple, inexpensive, and sustainable pathway. Tailoring the different chemical steps of catalyst preparation allow the faceted morphology to be maintained while reducing the organic leftover. Moreover, this work shows the key role of the halide ions on the nanoparticles shaping that occurs during the reduction step under H2. The predominant role of the {111} facets on the performance of the resulting supported nanocatalysts is also demonstrated. Indeed, catalytic tests in selective hydrogenation of polyunsaturated hydrocarbons performed for both faceted nanocatalysts and reference Ni show a clear selectivity enhancement for the former. The positive impact of {111} faceted Ni catalysts on hydrogenation selectivity is of particular interest to reduce the purification steps after the catalyzed reaction. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports the preparation of meso-structured rare earth (Eu3+, Sm3+ and Er3+)-doped Y2O3 films using the evaporation induced self-assembly (EISA). Thin films with ∼30% of porous volume and pore diameter of 9nm, stability up to 680°C were prepared using a specific polyethylene oxide based copolymer structuring agent. X-ray diffraction analysis was performed to study the crystallization of the inorganic network and the porosity. Time-resolved small angle X-ray scattering (SAXS), atomic force microscopy (AFM) and environmental ellipsometry porosimetry (EEP) techniques were used to complete the characterization of the films. The luminescent properties of these layers, i.e. fluorescence spectra and decay profiles, were investigated, showing the optical features characteristic of these lanthanide ions incorporated in the Y2O3 lattice. [Copyright &y& Elsevier]

Abstract: The thermal stability of anatase TiO2 mesoporous thin films has been considerably increased up to 800°C by substituting a fraction of Ti cations by Nb. Mesoporous mixed oxide films Ti1−x Nb x O2, with x =Nb/(Nb+Ti) ranging from 0 to 1, and homogeneous crystalline walls have been successfully prepared from chloride precursors and non-ionic block copolymer templates. They all exhibit a uniaxially distorted Im3m bcc mesostructure with the a lattice parameter ranging from 14 to 19nm. Films have been characterised by simultaneous in situ SAXS and WAXS investigations during thermal treatment. Transmission electron microscopy and UV–visible ellipsometry were used to confirm the structure, the porosity and the good optical quality. A high porosity of 40% (pore size estimated at 7nm) was maintained for the 10% Nb-doped films above the temperature of crystallisation and a bandgap of 3.40eV has been measured after annealing at 500°C. [Copyright &y& Elsevier]

Abstract: Herein we report on a new chemo sensor based on ligand induced plasmon band shift of gold nanoparticles [F. Goettmann, A. Moores, C. Boissière, P. Le Floch and C. Sanchez, Small (2005) 636. ]. Phosphininine stabilized gold nanoparticles were hosted in periodically organized mesoporous silica thin films. These layers feature a strong absorption in the UV–visible spectrum caused by the nanoparticles plasmon band. The position of the latter is unusual, due to the electronic properties of the phosphinine (the phosphorus analog of pyridine). This user-friendly system proved to be remarkably efficient in UV–visible detection of thiols and small phosphines. The sensor is sensitive, selective and reusable. Exchange processes at gold nanoparticles surface in solution or hosted were also discussed in regard of the plasmon band position. [Copyright &y& Elsevier]

A straightforward crack-patterning method is reported allowing the direct formation of periodic cracks in metal-organic framework (MOF) nanoparticle films during dip-coating deposition. The crack propagation and periodicity can be easily tailored by controlling the evaporation front and the withdrawal speed. Several MOF-patterned films can be fabricated on large surfaces and on several substrates (flat, curved or flexible) including the inner surface of a tube, not achievable by other lithographic techniques. We demonstrate that the periodic cracked arrays diffract light and, due to the MOF sorption properties, photonic vapor sensors are fabricated. A new concept of 'in-tube', MOF-based diffraction grating sensors is proposed with outstanding sensitivity that can be easily tuned 'on-demand' as function of the desired detection range. [ABSTRACT FROM AUTHOR]

A straightforward crack-patterning method is reported allowing the direct formation of periodic cracks in metal-organic framework (MOF) nanoparticle films during dip-coating deposition. The crack propagation and periodicity can be easily tailored by controlling the evaporation front and the withdrawal speed. Several MOF-patterned films can be fabricated on large surfaces and on several substrates (flat, curved or flexible) including the inner surface of a tube, not achievable by other lithographic techniques. We demonstrate that the periodic cracked arrays diffract light and, due to the MOF sorption properties, photonic vapor sensors are fabricated. A new concept of 'in-tube', MOF-based diffraction grating sensors is proposed with outstanding sensitivity that can be easily tuned 'on-demand' as function of the desired detection range. [ABSTRACT FROM AUTHOR]

2D photonic metal–oxide‐framework‐based homo‐ and hetero‐structures are fabricated by soft lithographic approaches. As shown by A. Cattoni, M. Faustini and co‐workers, these materials can be used as selective photonic sensing platforms. Detection of toxic vapors such as styrene are performed using an easy transduction method, compatible with smart‐phone camera technologies. [ABSTRACT FROM AUTHOR]

Complex 3D macrostructured nanoparticles are transformed from amorphous silica into pure polycrystalline α-quartz using catalytic quantities of alkaline earth metals as devitrifying agent. Walls as thin as 10 nm could be crystallized without losing the architecture of the particles. The roles of cation size and the mol% of the incorporated devitrifying agent in crystallization behavior are studied, with Mg2+, Ca2+, Sr2+ and Ba2+ all producing pure α-quartz under certain conditions. [ABSTRACT FROM AUTHOR]

Gold quantum dots exhibit distinctive optical and magnetic behaviors compared with larger gold nanoparticles. However, their unfavorable interaction with living systems and lack of stability in aqueous solvents has so far prevented their adoption in biology and medicine. Here, a simple synthetic pathway integrates gold quantum dots within a mesoporous silica shell, alongside larger gold nanoparticles within the shell's central cavity. This "quantum rattle" structure is stable in aqueous solutions, does not elicit cell toxicity, preserves the attractive near-infrared photonics and paramagnetism of gold quantum dots, and enhances the drug-carrier performance of the silica shell. In vivo, the quantum rattles reduced tumor burden in a single course of photothermal therapy while coupling three complementary imaging modalities: near-infrared fluorescence, photoacoustic, and magnetic resonance imaging. The incorporation of gold within the quantum rattles significantly enhanced the drug-carrier performance of the silica shell. This innovative material design based on the mutually beneficial interaction of gold and silica introduces the use of gold quantum dots for imaging and therapeutic applications. [ABSTRACT FROM AUTHOR]

Quartz has been widely used as a bulk material in optics, the microelectronic industry, and sensors. The nanostructuring and direct integration of oriented quartz crystals onto a semiconductor platform has proven to be challenging. However, here, a new approach is presented to integrate epitaxial quartz films with macroperforations within the range of 500 nm and 1 μm using chemical solution deposition. This method constitutes an appealing approach to develop piezoelectric mass sensors with enhanced resonance frequencies due to the thickness reduction. Perforated quartz films on (100)-silicon are prepared from amorphous silica films deposited via dip-coating and doped with metal cations that catalyze quartz crystallization. The metal cations are also active in the formation of the macroperforations, which arise due to a phase separation mechanism. Cationic surfactant-anion-metal cation assemblies stabilize droplets of water, creating an indentation in the hydrophilic silica matrix which remains after solvent evaporation. Many cations induce phase separation, including Li+, Na+, Sr2+, Mn2+, Fe2+/Fe3+, Ca2+, Ce3+ and La3+ but only the Sr2+ and Ca2+ cations in this series induce the epitaxial growth of α-quartz films under the conditions studied. The combination of sol-gel chemistry and epitaxial growth opens new opportunities for the integration of patterned quartz on silicon. [ABSTRACT FROM AUTHOR]

Gold phosphide (Au2P3) is known as a crystalline metastable phase at the macroscale. In this paper, the formation of Au2P3 nanostructures is investigated. Here, white phosphorus (P4) is used as a soluble phosphorus donor and reacted on 16 nm gold nanoparticles, in a strategy similar to the one previously used for the production of various metal phosphide nanoparticles including Ni2P, Pd5P4, PdP2, Cu3P and InP. Moderate temperature (250 °C for up to 6 h) gives a reaction limited to the surface of the nanoparticles, while the unreacted P4 stays in solution. This surface modification is then optimized by reducing the stoichiometry of P4 to Au : P = 10 : 1 and lowering the temperature to 110 °C. Interestingly, this surface modification shields the plasmon band against ligand exchange with thiols, providing more robust nanoparticles. The reaction is then conducted under harsh conditions (320 °C for 3 h) to produce crystalline Au2P3. This triggered the aggregation of the starting nanoparticles into larger nanostructures such as nanowires. Moreover, the formation of composite Au2P3–Au nanostructures is observed, where the gold phosphide domains are systematically larger than the unreacted gold nanoparticles. This suggests that gold is particularly reluctant to form gold phosphide, which relates to the metastable character of this phase. [ABSTRACT FROM AUTHOR]

A novel technique combining inkjet printing (IJP), evaporation-inducedself-assembly (EISA), and click chemistry is implemented for elaboratingmesoporous silica-based multifunctional microdots arrays. The microdotsare in situ azide-functionalized with (3-azidopropyl)triethoxysilane(AzPTES). AzPTES is directly added to the initial sol before IJP andco-condenses with the silica precursor (TEOS) during the evaporation-inducedself-assembly (EISA) of micelles on the substrate. After extractingthe surfactants to release the porosity, model alkynes, namely propargylalcohol, methyl pent-4-ynoate, ethynylferrocene, and N-propargyl-4-amino-1,8-naphthalimide, are grafted by the azide–alkyneCuAAC click reaction. The demonstration is established that the clickreaction is nearly quantitative and occurs in the whole volume ofthe microdots attesting the accessibility of the azide groups. Byintegrating an alkyne-containing silylated precursor in a similarroute, azide-containing functional groups are anchored in the microdotsby click reaction. A demonstration of the multifunctionalization ofsuch microdots arrays is achieved by reacting clickable dyes on alternatealkyne- and azide-functionalized lines of microdots, as evidencedby confocal fluorescence microscopy. Such multifunctional mesoporoussilica microdots arrays offer promising perspectives for biosensingapplications. [ABSTRACT FROM AUTHOR]

A comparative study of the degradation in a model phosphatebufferedsaline (PBS) medium of mesoporous mixed silica–zirconia oxidesand hybrid organosilica materials is reported, and their thermodynamicand kinetic stability are discussed. Thin film morphology was usedto monitor the degradation rates of all these materials for the firsttime directly in liquid and undersaturated medium. The introductionof zirconium centers in mesoporous materials strongly inhibits degradationand allowed the self-limitation of soluble silica concentration inthe immediate environment of the vector. This avoids renucleationof potentially toxic silica small nanoparticles with uncontrolledsurface chemistry in the release medium. Chemical modifications (hybridationor zirconia doping) of mesoporous silica allow the fine-tuning ofits degradation from hours to days. Methylated thin films are highlystable when the functionalization ratio is high (50%). The hybridationby mercaptopropyl and aminopropyl moieties can be successfully performedwithout any high thermal treatment, allowing not only slowing downsilica dissolution but also opening the possibility to introduce inone-pot other thermally fragile molecules into the vector. Dissolutionrates K measured for the first time at different biologically relevanttemperatures follows an Arrhenius law: K= KoExp(−Ea/RT). Stabilities of these chemically modified silicas aremainly associated with a strong decrease of the pre-exponential factor K0of modified silicas. Counterintuitively, activationenergies Eadecrease with increasing thehybrid/silica or the zirconia/silica ratios. [ABSTRACT FROM AUTHOR]

Nanoparticles of mesoporous MIL-100(Al, Cr or Fe) metal-organic frameworks were synthesized by a microwave-assisted solvothermal route with green solvents. The optimization of yield, crystallinity, and particle size was achieved through the control of synthetic parameters such as temperature, heating rate, and dwelling time. The particle size strongly depends on the metallic cation and the metal and linker precursors; nanoparticles smaller than 100 nm were obtained for iron and chromium based MIL-100. Finally, stable colloidal solutions of iron and chromium MIL-100 nanoparticles were used for thin layer dip-coating deposition, which resulted in high optical quality thin films, the porosity of which was investigated by environmental ellipsometric porosimetry. [ABSTRACT FROM AUTHOR]

The widely used preparation of Ni0 nanoparticles from [Ni(acac)2] (acac=acetylacetonate) and oleylamine, often considered to be a thermolysis or a radical reaction, was analyzed anew by using a combination of DFT modeling and designed mechanistic experiments. Firstly, the reaction was followed up by using TGA to evaluate the energy barrier of the limiting step. Secondly, all the byproducts were identified using NMR spectroscopy, mass spectrometry, FTIR, and X-ray crystallography. These methods allowed us to depict both main and side-reaction pathways. Lastly, DFT modeling was utilized to assess the validity of this new scheme by identifying the limiting steps and evaluating the corresponding energy barriers. The oleylamine was shown to reduce the [Ni(acac)2] complex not through a one-electron radical mechanism, as often stated, but as an hydride donor through a two-electron chemical reduction route. This finding has strong consequences not only for the design of further nanoparticles syntheses that use long-chain amine as a reactant, but also for advanced understanding of catalytic reactions for which these nanoparticles can be employed. [ABSTRACT FROM AUTHOR]

In the field of catalysis by metals, a new insight for the nanodesign of supported heterogeneous catalysts is the tailoring of metallic nanoparticles. In this work, well-faceted monometallic nanoparticles (Pd, Pt, Ni) exposing mostly the {111} crystallographic facet are obtained in aqueous solution and are deposited on an alumina support. The involved mechanisms of nanoparticles formation are determined and are evidenced to be different as a function of the nature of the metal. In the case of palladium the mechanism consists in an oriented attachment of palladium nanoparticles leading to the energetically most favourable stacking of nanoparticles, at the origin of the early differentiation of the nanoparticles shapes and of the formation of the well-faceted palladium nanoparticles. In the case of platinum, the mechanism seems to be a combination of aggregation of already reduced nuclei and direct reduction depending on the experimental conditions. In the case of the less reductible metal, nickel, well-faceted nanoparticles are not obtained during the synthesis and only a thermal activation under hydrogen can engender their formation. The impact of the {111} crystallographic facet for platinum and nickel is very important and induces a drastic increase of selectivity towards olefins formation with a selectivity close to the one of a palladium catalyst which is the most selective metal for the selective hydrogenation of poly-unsaturated hydrocarbons. [ABSTRACT FROM AUTHOR]

Nanoporous barium titanate and lead titanate thin films (∼100nm calculated from ellipsometric data) are prepared starting fromsol–gel solutions modified with a commercially available block-copolymerand evaporation-induced self-assembly methodology. The tuning of thethermal treatment followed by in situ ellipsometry allows the decompositionof the organic components and of the structuring agent leading tothe formation of porous tetragonal crystalline perovskite structuresas observed by XRD, HRTEM, SEM, and ellipsoporosimetry. Both nanoporousbarium titanate and lead titanate thin films present local piezoelectricand ferroelectric behavior measured by piezoresponse force microscopy(PFM), being promising platforms for the preparation of the generationof new multifunctional systems. [ABSTRACT FROM AUTHOR]

Aerosol-generated mesoporous organosilica submicronic spheres have been converted into porous silicon oxycarbide (SiCO) glasses by pyrolysis at 1000 °C in an inert atmosphere. Spherical mesoporous particles obtained from acidic solutions of 1,2-bis(triethoxysilyl) ethane and Pluronic® F127 structuring agent were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption/desorption, and multi nuclear solid-state magic-angle spinning (MAS) NMR. These particles were then pyrolyzed at 1000 °C and transformed into a SiCO phase as evidenced by 29Si MAS NMR, while TEM shows preserved mesoporosity, unfortunately difficult to access owing to the presence of an outer layer of dense silica. [ABSTRACT FROM AUTHOR]

Abstract: Solid-state NMR methods based on dipolar and J-derived experiments such as CP, MAS-J-HMQC and MAS-J-INEPT MAS have been developed in the frame of the {31P,29Si} spin pair. The potential of these techniques has been demonstrated using model compounds including crystalline silicophosphate phases (Si5O(PO4)6 and various SiP2O7 polymorphs). Spatial interactions as well as through-bond connectivities were established. Evaluation of isotropic 2 J P–O–Si coupling constants has been established by careful analysis of the HMQC and INEPT build-up curves under fast MAS. The efficiency of the 31P→ 29Si CP MAS experiment for the detailed characterization of Si–O–P mesoporous materials (at low temperature) was demonstrated. The incorporation of P atoms in the silica network has been proved unambiguously. Such materials could be appropriate for biocompatibility purposes. [Copyright &y& Elsevier]

P4reaction with metal NPs (In, Pb, Zn) provides an easy access to the corresponding metal phosphide NPs in a soft and stoichiometric reaction. Size-influence on the reactivity is investigated in the case of indium. [ABSTRACT FROM AUTHOR]

In article number 1802136 Cédric Boissière, Cédric Tard, Jennifer Peron and co‐workers present the synthesis of ultra porous nanostructured iridium‐based microspheres using a cheap and easily scalable water‐based process. These hierarchical catalysts are active and stable towards the oxygen evolution reaction. They are easily processed to make percolated and highly porous anode catalyst layers that are ideal for gas, water, proton and electrons transport when integrated into the proton exchange membrane of electrolysis cells. [ABSTRACT FROM AUTHOR]

Iridium oxide is the gold‐standard catalyst for the oxygen evolution reaction (OER) in acidic media due to its unmatched activity and stability. Here, a new catalyst architecture comprising a nanoneedle network of iridium‐containing oxides assembled into macroporous micrometric particles with ≈75% of porosity is reported. The rationally designed porous hierarchical structure optimizes the accessibility of reactants and products to the surface of the nanoparticles and maximizes catalyst activity. The materials are easily prepared from aqueous solutions by an industrially viable spray‐drying route through an evaporation self‐assembly mechanism. The versatility of the process enables the preparation of mixed oxides with low iridium content, particles with tunable crystallinity, and various iridium surface species with high electrochemical activity. Highly porous Ir0.7Ru0.3O2 outperforms commercial iridium oxide. These materials also represent an ideal platform to assess the reactivity of the iridium and oxygen species involved in the oxygen evolution reaction. Furthermore, it is demonstrated that these highly porous particles are optimal building blocks to be integrated into catalyst layers, without the drawbacks associated with the use of discrete nanoparticles. Fresh‐ and end‐of‐test membrane–electrode assemblies' characterization shows that their particular architecture is preserved upon catalyst layer preparation and after operation in a proton‐exchange membrane electrolysis cell. Ultraporous nanocrystalline IrOx microspheres are optimal architectures to build highly porous catalyst layers. Easily prepared by a spray‐drying process, they consist of a nanoneedle network of iridium‐containing oxides assembled into macroporous micrometric particles with ≈75% of porosity. While being very active toward the oxygen evolution reaction, their morphology is maintained when assembled and tested in a proton exchange membrane electrolysis cell. [ABSTRACT FROM AUTHOR]

The combination of sol‐gel chemistry and epitaxial growth provides direct access to the integration of piezoelectric macroporous quartz, epitaxially grown on (100)‐silicon substrates. A. Carretero‐Genevrier and co‐workers demonstrate on page 5494 that the interplay between temperature, humidity, catalyst content, and epitaxial growth plays a key role for the bottom‐up fabrication of macroporous quartz on silicon substrates. [ABSTRACT FROM AUTHOR]

The cover page of the "European Journal of Inorganic Chemistry" is presented.