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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]

Periodic mesoporous Eu3+doped titania materials were obtained through the EISA (Evaporation Induced Self Assembly) process. Eu3+ions, entrapped within the semi-crystalline walls of the highly porous framework, appear to be advantageous during the probing of surface photochemical reactions. Its emission intensity is very sensitive to the presence of physisorbed molecules, in gas or liquid phase, that reside within the pores. In particular, strong fluctuations in intensity of the 5D0→ 7F2transition were observed under UV light exposure on the time scale of tens of seconds. The emission modulation dynamics show a strong correlation with the crystallinity of the titania matrix. Correlation of the emission with the photocatalytic activity of the semiconductor for photodegradation of an organic molecule is observed. A model is proposed to describe the involved mechanisms. [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]

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]

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]

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 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 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]