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One of today's major world challenges is the accumulation and the storage of tens of millions of tons per year of final materials resulting from the incineration of domestic and industrial waste. This raises the question of the recycling of these "raw materials", while making allowance for environmental, economic, social and public health aspects. Our strategy targets the incorporation of waste incineration by-products in a totally circular economy. We propose an innovative process combining templated sol–gel growth of an inorganic or hybrid silica-based network with a solubilized fraction of bottom ash coming from the combustion of industrial and household wastes. The resulting materials engineered via aerosol processing demonstrate maximum adsorption capacity of model pollutant compounds (1-2 dichlorobenzene) competitive with activated carbons currently used in modern incineration plants. We believe that they have the potential to replace conventional activated carbon commonly used in incineration plants, enabling the first step of the long road of recycling final waste. Highlights: Sol–gel process combined with spray-drying enables part of bottom ash to be recycled. Mesoporous silica-based particles with a high content of bottom ash derivatives were synthesized. Composite particles display promising adsorption properties towards gaseous model pollutants. [ABSTRACT FROM AUTHOR]

Combining high activity and stability, iridium oxide remains the gold standard material for the oxygen evolution reaction in acidic medium for green hydrogen production. The reasons for the higher electroactivity of amorphous iridium oxides compared to their crystalline counterpart is still the matter of an intense debate in the literature and, a comprehensive understanding is needed to optimize its use and allow for the development of water electrolysis. By producing iridium-based mixed oxides using aerosol, we are able to decouple the electronic processes from the structural transformation, i.e. Ir oxidation from IrO2 crystallization, occurring upon calcination. Full characterization using in situ and ex situ X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and transmission electron microscopy allows to unambiguously attribute their high electrochemical activity to structural features and rules out the iridium oxidation state as a critical parameter. This study indicates that short-range ordering, corresponding to sub-2nm crystal size for our samples, drives the activity independently of the initial oxidation state and composition of the calcined iridium oxides. The origins of the superior catalytic activity of poorly crystallized Ir-based oxide material for the OER in acid is still under debate. Here, authors synthesize porous IrMo oxides to deconvolute the effect of Ir oxidation state from short-range ordering and show the latter to be a key factor. [ABSTRACT FROM AUTHOR]

Organic−inorganic hybrid mesostructured silicas are prepared, without stirring (at pH = 0.0) and with stirring (at pH = 0.6) to obtain isolated and gyroidal-like attached silica grains with incorporated triblock P123 poly (ethylene oxide)-poly (propylene oxide)–poly (ethylene oxide) copolymers. Selected hybrids are submitted to various thermal and aging treatments for studying hydrolysis and oxidation of PEO and PPO chains. Two complementary spectroscopic techniques are used: near-infrared (NIR) with measurements performed in diffuse reflectance, as well as 1H and 13C liquid- and solid-state nuclear magnetic resonance (NMR) to study the mobility and stability of PEO and PPO chains. With precipitated fresh hybrids, the ratio of PEO over (PEO + PPO) units is lower (30% ± 5%) than in theory. This ratio also decreases depending on temperature when a hydrothermal treatment is applied. An acidic hydrolysis involving both PEO and PPO chains, with generated fragments eliminated by washing with water and/or synthesis liquor, is then demonstrated. For comparison, another hybrid obtained by spray drying via evaporation-induced self assembly mechanism is also studied. Its NMR signals are much more stable than those of the samples prepared by precipitation. Depending on aging time, thermal history, and materials processing, the textural properties and template decomposition inside mesostructured silica are found significantly different. The influence of the hydrolysis and oxidation of the template onto final materials texture is likely to be as important as the processing conditions. Highlights: Mesostructured "hybrids" containing silica and P123 triblock copolymers obtained by precipitation (in acidic HCl solution) and spray drying are compared. A copolymer acidic hydrolysis is observed for all samples having been heated during synthesis (that is, hydrothermal treatment for synthesis by precipitation, or drying temperature for spray drying experiments). 1,2-ethanediol and peroxide traces associated with the copolymer oxidative decomposition are identified by NMR. The temperature of the heat treatment applied for HT is directly correlated with the remaining EO/(EO + PO) weight %. The NMR study of polymer chains mobility confirms the dehydration and retraction of hydrated PEO chains from silica walls upon temperature increase. We proved for the first time that this effect, now well known for precipitated SBA-15 materials, also occur for spray-dried samples. [ABSTRACT FROM AUTHOR]

Mesoporous thin films were prepared by dip-coating with a purely aqueous method, as a substitute for the alcohol-based evaporation-induced self-assembly route. Unlike other aqueous routes that require a very slow pulling rate possible only using high performance dip-coaters, as a result of the high surface tension of water, this new process works with standard dip-coaters and at similar pulling rates as are used for the evaporation-induced self-assembly route. This unique asset is the result of the synthesis of prefabricated self-assembled silicate/organic hybrid micelles. These building blocks are concentrated before use, which provides a gelling edge after moderate evaporation. As a result, defect-free continuous mesoporous films with well-organized hexagonally packed pores were prepared after optimization of both the evaporation rate of the solution of hybrid micelles and the dip-coater pulling rate. Graphic Abstract: The transmission electron microscopy observation reveals the hexagonally packed structure of mesoporous silica film. This nanostructure has already been observed on films prepared with the evaporation-induced self-assembly process, but it is the first time it is obtained with a pure aqueous method, based on prefabricated hybrid micelles, not on controlled evaporation of mesophases. [ABSTRACT FROM AUTHOR]

Integrative sol-gel chemistry based strategies allow, through the strong coupling between materials chemistry and advanced processing, the fabrication of functional inorganic and hybrid materials. The following article will highlight some of the main accomplishments performed during the last years in the design of nano- and multi-scale structured materials shaped as thin films, powders and monoliths with additional functionalities and outstanding properties in several fields of application such as optics, catalysis and nanomedicine. In particular we discuss the key role played by the adapted liquid processing of sol-gel based solution. We will describe some technologies (including dip coating, spray drying, droplet-microfluidics, ink-jet and foaming) in which a high degree of control in term of liquid shaping/evaporation/manipulation is required in order to achieve specific functionalities. [ABSTRACT FROM AUTHOR]

Hybrid silica coatings based on 3- glycidoxypropyltriethoxysilane (GPTES), tetraethylorthosilicate (TEOS) and colloidal silica were deposited on polycarbonate (PC) by the sol-gel method, in order to obtain a material with enhanced properties with respect to raw PC (mainly scratch resistance, hydrophobicity and density), and consequently reach increased durability. The necessity of performing a N-plasma treatment on PC (before coating deposition) was highlighted in order to obtain a good adherence between the coating and the substrate: XPS measurements showed that after treatment, nitrogenous radicals had formed on the PC surface and were able to link covalently with the sol during its deposition. Adherence was also higher when young sols (<8-day-old) were used. Different alkoxysilanes/colloidal silica ratios were tested to optimize the coating resistance: crack resistance of the coatings was found to be greater when the ratio was high. Scratch resistance of raw PC was enhanced as soon as PC was coated, irrespective of the alkoxysilanes/colloidal silica ratio or the sol ageing time. The density of the coatings was assessed by environmental ellipsometric porosimetry and found to be very high. Water contact angle measurements showed that the hydrophobicity of the coatings was inferior to raw PC. The addition in the sol of a small wt% of octyltriethoxysilane (OTES), 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FTES) and silicone surface additive (BYK-306) allowed a significant increase in hydrophobicity of the samples. [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]

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]

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]