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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]

Varnish layers are optical coatings that act as physico‐chemical barrier between the historical paint layers and the environment. Understanding how varnish materials protect historical paintings over time and in the presence of humidity or organic vapors is of central importance for art preservation. However, probing the behavior of varnish after aging in real conditions remains a challenge. Here the question is addressed by "reshaping" the varnish material from the masterpiece of G. Bellini, the "Transfiguration", into an optical layer; coupling in situ Ultraviolet‐Visible (UV–vis) and Infrared (IR) ellipsometries, the chemical state is correlated, optical properties and swelling of the varnish in presence of water and organic vapors. It shows that the varnish material aged since the 1950s still exhibits effective water repellence. The methodology may be applied to other relevant historical systems beyond paintings and may help in establishing more efficient preservation strategies for historical artworks. [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]

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]

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]

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]

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]

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]

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]

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]

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.

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]