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Bismuth vanadate (BiVO4), which has attractive applicability as a photoactive material, presents applications that range from catalysis to water treatment upon visible light irradiation. In this study, we develop a simple synthesis of &lt, 200 nm monoclinic BiVO4 nanoparticles, which were further deposited on transparent conductive substrates by spin coating and calcination, obtaining nanostructured films. The obtained nanostructured BiVO4 photoanodes were tested for water oxidation, leading to promising photocurrents exhibiting competitive onset potentials (~0.3 V vs. RHE). These nanoparticulate BiVO4 photoanodes represent a novel class of highly potential materials for the design of efficient photoelectrochemical devices.

Hot-injection has become the most widespread method used for the synthesis of perovskite quantum dots (QDs) with enormous interest for application in optoelectronic devices. However, there are some aspects of the chemistry involved in this synthesis that have not been completely investigated. In this work, we synthesized ultra-high stable CsPbI

All inorganic halide perovskite nanocrystals (NCs) are considered as fascinating materials for a wide range of optoelectronic applications encompassing photovoltaics, lasing, sensing, and photocatalysis due to their outstanding optoelectronic properties. Herein, it is demonstrated that the photoelectrochemical behavior of CsPbBr3 NC films can be tailored through engineering the selective contacts and accepting species in the electrolyte. This concept has been successfully applied to the photoelectrochemical oxidation of benzyl alcohol (BzOH) to benzyl aldehyde (BzCHO) and the reverse photoelectrochemical reduction of BzCHO to BzOH, demonstrating that CsPbBr3 NCs activate both reactions with photocurrents up to 40 μA cm 2 toward BzCHO production and 5 μA cm 2 for the reverse reaction at 0.15 V versus normal hydrogen electrode. The obtained results highlight the huge potential and versatility of halide perovskite NCs for photoelectrocatalytic applications, validating the implementation of these materials for a wide range of solar-driven complex organic transformations, and emphasizing the urgent need for stabilization strategies to move beyond the proof-of-concept stage to relevant technological developments.

Hot-injection has become the most widespread method used for the synthesis of perovskite quantum dots (QDs) with enormous interest for application in optoelectronic devices. However, there are some aspects of the chemistry involved in this synthesis that have not been completely investigated. In this work, we synthesized ultra-high stable CsPbI3 QDs for more than 15 months by controlling two main parameters: synthesis temperature and the concentration of capping ligands. By increasing the capping ligand concentration during the QD synthesis, we were able to grow CsPbI3 in a broad range of temperatures, improving the photophysical properties of QDs by increasing the synthesis temperature. We achieved the maximum photoluminescence quantum yield (PLQY) of 93% for a synthesis conducted at 185 °C, establishing an efficient surface passivation to decrease the density of non-radiative recombination sites. Under these optimized synthesis conditions, deep red LEDs with an External Quantum Efficiency (EQE) higher than 6% were achieved. The performance of these LEDs is higher than that of the reported CsPbI3 QD-LEDs containing standard capping agents, without additional elements or further element exchange. We show that it is possible to produce stable CsPbI3 QDs with high PLQY and red emission beyond the requirement of the Rec. 2020 standards for red color.

Lead sulfide (PbS) nanocubes are produced by a very simple solvothermal procedure that uses a unique molecule, ethylenediamine, as solvent and capping ligand to control the size and shape of the nanocrystals. Detailed structural, optical, and photoelectrochemical evaluation confirms the suitability of these nanoparticles for photocapacitive applications, when synergistically combined with spin‐coated BiVO4 photoelectrodes, as derived from the estimated energy diagram. Furthermore, the p–n junction facilitates the photo‐oxidation of PbS nanoparticles under light irradiation. In the dark, the photogenerated charges are released providing an electric output response with a solar‐to‐current efficiency of 0.042%, storing extra energy to the H2 produced by water splitting when the BiVO4 photoanode works under illumination. Herein, the importance of the synthetic route and methodology to ensemble materials for advanced solar energy storage applications is highlighted., We acknowledge financial support from the Ministerio de Ciencia, Innovación y Universidades, Spain through the project number ENE2017‐85087‐C3‐1‐R and Ramon y Cajal Fellowship (grant no. RYC‐2018‐025222‐I). Universitat Jaume I is also acknowledged for funding (project UJI—B2018‐71). Université de Tunis El‐Manar also acknowledges the Tunisian Ministry of Higher Education and Scientific Research (MHESR) for the financial support of this work.

This is the pre-peer reviewed version of the following article: Easy Formation of Functional Liposomes in Water Using a pH‐Responsive Microbial Glycolipid: Encapsulation of Magnetic and Upconverting Nanoparticles, which has been published in final form at https://doi.org/10.1002/cnma.201900318. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. The compartmentalization of colloids into topologically closed, vesicular, microphases offers an attractive mean to concentrate a functional cargo in aqueous solutions for a range of biomedical, cosmetic, and biotechnological applications. In this paper, we develop a simple, phospholipid‐free, phase change method employing a pH‐responsive glycolipid. The method is applied to the encapsulation of a sonicated, metastable, aqueous dispersion of functional colloids in the lumen of lipid vesicles: uncoated magnetic maghemite γ‐Fe2O3 and oleic‐acid coated upconverting NaYF4 : Yb/Ln (Ln=Er or Tm) nanoparticles (NPs). We find a stable liposomal dispersion containing a sub‐population of crowded liposomes with high concentrations of NPs. The encapsulated NPs, formed at nearly neutral pH and room temperature, are stable over time and towards extrusion. The vesicular microphase is entirely composed of pH‐responsive glycolipids, which undergo a pH‐mediated mesoscopic structural transition from an open lamellar (24). We also show that encapsulation successfully works with a stable colloidal aqueous dispersion of iron clusters stabilized in ferritin cages. This compartmentalization approach combining self‐assembly with an orthogonal nonequilibrium dispersion of nanoparticles shows untapped potential for synthesizing unusual classes of mixed matter.

Transparent upconverting hybrid nanocomposites are exciting materials for advanced applications such as 3D displays, nanosensors, solar energy converters, and fluorescence biomarkers. This work presents a simple strategy to disperse upconverting b-NaYF4:Yb3+/Er3+ or Tm3+ nanoparticles into low cost, widely used and easy-to-process polydimethylsiloxane (PDMS)-based organic–inorganic hybrids. The upconverting hybrids were shaped as monoliths, films or powders displaying in the whole volume Tm3+ or Er3+ emissions (in the violet/blue and green/red spectral regions, respectively). For the first time, hyperspectral microscopy allows the identification at the submicron scale of differences in the hybrids' emission colour, due to variations in the relative intensity of the distinct components of the upconversion spectrum. The effect is attributed to the size distribution of the agglomerates of nanoparticles, highlighting the importance of studying the emission at submicron scales, since this effect is not observable in measurements recorded in larger areas.

In recent years, the interest in modelling activated sludge (AS) systems by means of Computational Fluid Dynamics (CFD) techniques has significantly increased. This work shows a successful case study combining CFD hydrodynamics and biokinetic modelling. The hydrodynamics is analysed by using the Reynolds-averaged Navier-Stokes equation for incompressible non-Newtonian fluids and SST turbulence model. Biokinetics has been included in the CFD as transport equations with source and sink terms defined by the Activated Sludge Model n°1 (ASM1). Furthermore, a strategy for reducing the computational cost while maintaining accuracy of the results of these calculations has been proposed. This strategy is based on a two-step solver configuration and the definition of a variable timestep scheme. The resulting CFD-ASM approach permits a proper evaluation of denitrification in the anoxic tanks as well as the reproduction of nitrate and readily biodegradable substrate distributions. To demonstrate the strength of the proposed CFD-ASM, it has been used to evaluate the operation of a full-scale AS system and optimize its performance through changes in the biological reactor anoxic zone. The original configuration has been retrofitted and modified after detecting intrinsic defects in the fluid behaviour within the tank. This study has been assessed by analysing hydrodynamics in detail and validating the simulation results with tracer tests and flow velocity measurements. Substantial variations on the Residence Time Distribution have been confirmed when modifying the internal elements of the tank configuration: the wall-bushing and the stirrer positioning. As a result of this work, an influential short circuiting was corrected improving hydrodynamics and increasing mean residence time, all favouring denitrification efficiency. Outcomes of this study show the benefit of CFD when applied to AS tanks.

An ultrafast route to prepare up-converting single β-phase NaYF

An ultrafast route to prepare up-converting single β-phase NaYF4:Yb3+,Ln3+ (Ln: Er, Tm, or Tb) short nanorods (UCNRs) of high quality was developed. This new procedure affords reactive-surface nanorods that are easily coated by direct injection of suitable capping ligands. Thus highly crystalline nanorods with excellent UC fluorescence and good solvent-selective dispersion are obtained, which represents a significant advance in the field and enlarges their use for biomedical and other technological applications. Unlike other methodologies, the short reaction time provides a kinetic control over crystallization processes, and the β-phase and rod morphology is preserved regardless of the optically active Ln3+ ion. The UC emission was finely tuned by using the most popular Yb3+/Tm3+ and Yb3+/Er3+ pairs. More importantly, UCNRs doped with the unusual Yb3+/Tb3+ pair, with no ladder-like energy levels, provided a nice emission upon near-infrared excitation, which constitutes the first example of phonon-assisted cooperative sensitization to date in pure β-NaYF4 nanocrystals.

Up-conversion (UC) of infrared (IR) photons into visible radiation constitutes a promising strategy to enhance the light harvesting efficiency of photovoltaic and photoelectrochemical devices. In the present study, we integrate Er3+/Yb3+-codoped yttrium oxide (Y2O3) submicrometric particles with outstanding up-conversion properties into mesoporous titanium oxide (TiO2) structures sensitized with cadmium selenide (CdSe) for solar hydrogen generation. We demonstrate that the incorporation of these up-converting particles (UCP) leads to effective H2 generation with IR photons. Moreover, based on the analysis of the emission lifetimes, we show that the optical interaction between the emitting UCPs and the CdSe absorber occurs via a radiative emission–reabsorption process. The low cost and toxicity and excellent chemical and thermal stability of our UC phosphors allow envisaging them as real candidates for the new generation of long-term photoelectrochemical devices for solar H2 generation.

Delafossite materials like CuGaO2 have appeared as promising p-type semiconductor materials for their exploitation in tandem dye sensitized solar cells and water splitting photoelectrochemical cells. However, the intrinsic electronic properties of this material once nanostructured have not been extensively studied and fundamental knowledge is required in order to further develop photovoltaic and photoelectrochemical devices. In the present study, we report the main electrical properties of CuGaO2 nanoparticles and evaluate the effect of Mg doping. We determine for the first time the hole conductivity of mesoporous CuGaO2 using impedance spectroscopy, extracting values ranging from 1 to 10 x S cm(-1) in the interval of applied bias tested. We show that after Mg doping, the optical bandgap is red-shifted 0.15 eV and the conductivity increased one order of magnitude, indicating real p-type doping of the materials. Furthermore, after Mg doping the capacitance showed a Mott-Schottky behaviour reflecting the band bending of the semiconductor. In these conditions, the estimated acceptor density and the flat band potential were N-A =10(19) cm(-3) and V-FB = 0.23 V vs Ag/Ag+, respectively. When the material is not intentionally doped, the measured capacitance corresponds to the double layer capacitance, since the semiconductor is fully depleted in the testing conditions. (C) 2013 Elsevier Ltd. All rights reserved.

Multimodal light-harvesting soft systems able to absorb UV-to-NIR radiations and convert into visible emissions have drawn much attention in the last years in order to explore new areas of application in energy, photonics, photocatalysis, sensors, and so forth. Here, we present a new hybrid system combining a supramolecular photonic gel of naphthalimidederived molecules self-assembled into fibers and upconverting NaYF4:Yb/Tm nanoparticles (UCNPs). The hybrid system presented here manipulates light reversibly as a result of an optical communication between the UCNPs and the photoactive gel network. Upon UV irradiation, the system shows the characteristic emission at 410 nm from the photoactive organomolecule. This emission is also activated upon 980 nm excitation thanks to an efficient energy transfer from the UCNPs to the fibrillary network. Interestingly, the intensity of this emission is thermally regulated during the reversible assembly or disassembly of the organogelator molecules, in such a way that gelator emission is only observed in the aggregated state. Additionally, the adsorption of the UCNPs with the supramolecular gel fibers enhances their emissive properties, a behavior ascribed to the isolation from solvent quenchers and surface defects, as well as an increased IR light scattering promoted by the fibrillary network. The reported system constitutes a unique case of a thermally regulated, reversible, dual UV and IR light-harvesting hybrid soft material.

10 pages; International audience; Composite PVA/ZnO-nanorods fi bers, synthesized through co-axial flux extrusion exhibit higher anisotropic photonic properties, both in absorption and emission, as a result of the collective alignment of the ZnO nanorods along the main axis of the PVA fiber. This photonic anisotropy is triggered by a synergistic interaction between the PVA matrix, stretched above the glass transition temperature (Tg), and cooled down under strain. Compared with non-elongated fi bers that present an isotropic emission, composite fi bers previously submitted to a tensile stress absorb selectively UV emission when the polarized laser beam is parallel to the main axis of the fiber. In addition, their photolumincescence is also anisotropic, with a waveguide behavior along the main axis of the fiber. Mechanical properties of these composite fibers are also drastically improved, compared with pure PVA fibers: the longitudinal Young modulus of these fi bers is increased from 2 to 6 GPa upon ZnO addition, a value similar to those already observed for composite fi bers, prepared either with carbon nanotubes, or V 2 O 5 macroscopic fibers.

Nanostructured, doped Ce–Ti mixed oxides are potential materials for several applications such as pigments, catalysis, fuel cells, optical films, and gas sensors. In this article, a series of Pr-doped Ce–Ti oxides have been prepared by the solvothermal method. These compounds were characterized by XRD, Raman, N2 sorption, SEM and UV–VIS spectrophotometry techniques. The experimental results suggest that spherical morphology, nanocrystalline particles and high specific surface area (up to 180 m2 g-1) are achieved at low temperature with this free surfactant methodology. Under basic conditions, a single phase product is identified at high temperature (1000 ºC), while for acid or neutral conditions, secondary phases appear. Different colored materials, ranging from yellow to red, are obtained by varying the firing temperature, quantity of doping praseodymium and the pH of the reaction. The chemical stability of these oxides was tested in some industrial polymers or glazes.

The one-pot synthesis and properties of multifunctional hybrid mesoporous organosilica fibers with helical shapes are described. These hybrid mesoporous fibers are prepared without chiral elements and functionalized with a large variety of organic R functions (R = alkylthiols, phenylsulfonates, alkylphosphonates, dansyl, aminopropyl, fluoroalkyl, etc.). The resulting nanomaterials are thoroughly characterized by a variety of techniques. The use of a synergetic combination of achiral molecules as co-directing structuring agents, a surfactant, and an organofunctional silica precursor R-Si(OR) 3 allows, via carefully tuning of the main synthesis parameters and processing conditions, to control the shape, which is the anisotropic factor, of the hybrid nanofibers. The functionalization of the hybrid materials with fluorescent molecules (dansyl) and gold nanoparticles opens possibilities for sensor and catalytic applications, respectively. Moreover, these hybrid nanofibers can be easily transferred in organic solvents or in a "green" solvent such as water to make stable colloidal dispersions. This tunable functionality of nanofibers also allows their transferability into a variety of polymeric hosts (PVDF, PVBu, and PVP) allowing the formation of functional homogeneous nanocomposite hybrid membranes.

Cerium titanate structures present a high technological interest because of their optical and catalytic properties. This work reports the synthesis of these materials by a sol–gel methodology that allows mixed oxides with TiIV/CeIII, TiIV/CeIV or TiIV/CeIII–CeIV species to be obtained. Crystallization of CeO2–TiO2 mixed oxides and Ce2Ti2O7 pyrochlore phase was corroborated by XRD and Raman spectroscopy. Magnetic and EPR measurements were performed in order to clarify the oxidation state of the cerium ions in the system as a result of the easy oxidation of CeIII. The firing atmosphere is crucial for the CeIII/CeIV ratio, which is responsible for the different structure, but it also affects the colouration (yellow, green, brown). This methodology offers the possibility to modulate the Ce3+/Ce4+ content and particle sizes providing more ecological coloured pigments based on rare earth elements that could be interesting materials for advanced applications in catalysis.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

International audience; Core-shell and homogeneous distributions of functionalized cerium oxide nanoparticles within spray-dried mesostructured silica spheres are achieved by modification of synthesis parameters such as the templating agent and nanoparticle capping functions.

El present treball de millora educativa constitueix un exemple de millora en les pràctiques de laboratori de l’assignatura QU0924 Química Inorgànica III mitjançant la introducció de rúbriques com a instrument d’avaluació. Clàssicament, l’avaluació en el laboratori químic es feia de manera subjectiva, és a dir, el professor tenia la intuïció de qui estava seguint i fent correctament les pràctiques. A més a més, la distribució dels grups de treball de laboratori per parelles feia més dificultosa l’avaluació individual dels estudiants, que en molts casos no sabien molt bé amb quins criteris se’ls avaluava.La introducció d’una rúbrica per a avaluar les distintes competències dels estudiants al laboratori químic ha permès sistematitzar l’avaluació d’aquesta assignatura desglossant-la en les parts més importants que s’han de tenir en compte a l’hora d’avaluar i aportant-li una major objectivitat. Aquest fet es reflecteix en una major confiança del professor a l’hora de realitzar l’avaluació. A més, els alumnes tenen molt més clars quins són els criteris que utilitzarà el professor quan avalua, donant-los la oportunitat de centrar-se en les coses importants., El presente trabajo de mejora educativa constituye un ejemplo de mejora en las prácticas de laboratorio de la asignatura QU0924 Química Inorgánica III mediante la introducción de rúbricas como instrumento de evaluación. Clásicamente, la evaluación del laboratorio químico se solía hacer de manera subjetiva, es decir, el profesor tenía la intuición de quien estaba siguiendo y haciendo correctamente las prácticas. Además, la distribución de grupos de trabajo por parejas hacía aún más dificultosa la evaluación individual de los estudiantes, que en muchos casos no sabían muy bien con qué criterios se los iba a evaluar. La introducción de una rúbrica para evaluar las distintas competencias de los estudiantes de laboratorio químico ha permitido sistematizar la evaluación de esta asignatura dividiéndola en las partes más importantes que tienen que tenerse en cuenta a la hora de evaluar y aportándole mayor objetividad. Este hecho se refleja en una mayor confianza del profesor a la hora de realizar la evaluación. Además, los alumnos tienen mucho más claro cuáles son los criterios que el profesor utilizará cuando evalúa, dándoles la oportunidad de centrarse en las cosas importantes., The current work is an example of improvement in the laboratory practices of the subject QU0924 Química Inorgànica III through the introduction of rubrics as an evaluation tool. Classically, the evaluation of the chemical laboratory used to be carried out in a subjective way, in other words, the teacher had an intuition about who was following and developing correctly the practices. Moreover, the students distribution in work groups (in pairs) produced that the individual evaluation was more difficult, thus in several cases the students did not know which one was the evaluation criteria. The introduction of a rubric for the evaluation of the different student’s competences in the chemical laboratory has allowed a systematization of the evaluation of this subject dividing it in the most important parts that have to be taken into account when evaluating. This fact is translated into an increase in the confidence and objectivity of the teacher in the evaluation part. Moreover, the students have much more clear which is the criteria that the teacher is going to use when evaluating, giving them the chance of focusing in the important things.

Research on hybrid inorganic-organic materials has experienced an explosive growth since the 1980s, with the expansion of soft inorganic chemistry based processes. Indeed, mild synthetic conditions, low processing temperatures provided by “chimie douce” and the versatility of the colloidal state allow for the mixing of the organic and inorganic components at the nanometer scale in virtually any ratio to produce the so called hybrid materials. Today a high degree of control over both composition and nanostructure of these hybrids can be achieved allowing tunable structure-property relationships. This, in turn, makes it possible to tailor and fine-tune many properties (mechanical, optical, electronic, thermal, chemical…) in very broad ranges, and to design specific multifunctional systems for applications. In particular, the field of “Hybrid-Optics” has been very productive not only scientifically but also in terms of applications. Indeed, numerous optical devices based on hybrids are already in, or very close, to the market. This review describes most of the recent advances performed in this field. Emphasis will be given to luminescent, photochromic, NLO and plasmonic properties. As an outlook we show that the controlled coupling between plasmonics and luminescence is opening a land of opportunities in the field of “Hybrid-Optics”. C.S acknowledges the “Fondation du Collège de France”. S.P. is grateful to the Ecole Normale Supérieure de Lyon, the University Lyon 1 and the CNRS for support. L.D.C. acknowledges the project CICECO – Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when applicable co-financed by FEDER and COMPETE under the PT2020 Partnership Agreement. B.J.L. is grateful to the PPI project from Universitat Jaume I for financial support.

Nanocrystalline ZrO2 and WOx–ZrO2 catalysts with good control over the zirconia phase and the nature of the W species were synthesized by a microwave-assisted aqueous route. The monoclinic ZrO2 (m-ZrO2) and tetragonal ZrO2 (t-ZrOz) polymorphs were isolated through accurate control of the synthetic conditions, in acidic and basic media, respectively. The evolution of the zirconia and W species under annealing of the WOx–ZrO2 nanocomposites at 500 °C and 800 °C was studied, and the resulting materials were tested as catalysts for aldoxime dehydration and hydration of alkynes for the production of nitriles and carbonyls, respectively. In the dehydration reaction, the most active species are W(VI) in tetrahedral coordination, independently of the ZrO2 polymorph, while in the hydration reaction the zirconia phase plays a key role, as the tungsten doped t-ZrO2 appears to be the most active catalyst. F. G. is grateful to Ministerio de Educación, Cultura y Deporte for his PhD grant (AP2010-2748); B. J.-L. and F. G. thank the Spanish Government (MAT2011-27008 project) and University Jaume I (UJI, P1 1B2014-21). F. G. and A. C. thank financial support from Spanish Government-MINECO through “Severo Ochoa” (SEV 2012-0267). D. P., C. S. and K. V. would like to strongly acknowledge the Foundation du Collège de France for support and thank the French Commissariat à l'Energie Atomique et aux Energies Alternatives for financial support. SCIC from Universitat Jaume I and Servicio de Microscopía Electrónica at Universitat Politècnica de València are also acknowledged for instrumental facilities.

Copper-doped titanium dioxide materials with anatase phase (Cu-TiO2, atomic Cu contents ranging from 0 to 3% relative to the sum of Cu and Ti), and particle sizes of 12-15 nm, were synthesised by a solvo-thermal method using ethanol as the solvent and small amounts of water to promote the hydrolysiscondensation processes. Diffuse reflectance UV-vis spectroscopy show that the edges of absorption of the titania materials are somewhat shifted to higher wavelengths due to the presence of Cu. X-ray photoelectron spectroscopy (XPS) indicate that Cu(II) is predominant. Photocatalytic CO2 reduction experiments were performed in aqueous Cu-TiO2 suspensions under UV-rich light and in the presence of different solutes. Sulfide was found to promote the efficient production of H-2 from water and formic acid from CO2. The effect of the Cu content on the photoactivity of Cu-TiO2 was also studied, showing that copper plays a role on the photocatalytic reduction of CO2., Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2012-32315) is gratefully acknowledged. F.G. and B.J.-L. are thankful for financial support from Spanish Government (AP2010-2748 PhD grant and MAT2011-27008 project) and Jaume I University (P1 1B2014-21 project). SCIC from Jaume I University and Servicio de Microscopia Electronica at Universitat Politecnica de Valencia are also acknowledged for instrumental facilities. A.V.P. is grateful to both the Consejo Superior de Investigaciones Cientifficas (CSIC) and the European Social Fund (ESF) for a JAE-Doc postdoctoral grant. Lichen Liu is gratefully acknowledged for assistance in recording HRTEM images.

We report facile fabrication of advanced hybrid silica–spinel iron oxide (maghemite) composite microspheres built with both superparamagnetic nanoparticles for MR imaging, hyperthermia, and a hybrid mesoporous matrix enabling the transport of bioactive molecules for in vivo biomedical applications. Elaboration of such multifunctional platforms is performed by spray drying a sol of tunable composition that allows one to control the size and amount of magnetic particles embedded in the matrix, without aggregation, and to adjust the size and the surface chemical properties of the porous silica cavities. The resulting nanocomposites (γ-Fe2O3 8 nm particles in silica matrices from TEOS templated by CTAB or P123, without or with functionalisation with –Ph, –SH or –NH2) were characterised by chemical analysis, XRD, TEM, BET, FTIR and magnetisation measurements. Tests of the materials both as MRI T2-contrast agents and as heating sources of hyperthermia are presented in support of potential applications in diagnosis and therapy.

This manuscript reports the synthesis and characterization of the first organic-inorganic hybrid material exhibiting efficient multimodal spectral converting properties. The nanocomposite, made of Er(3+), Yb(3+) codoped zirconia nanoparticles (NPs) entrapped in a di-ureasil d-U(600) hybrid matrix, is prepared by an easy two-step sol-gel synthesis leading to homogeneous and transparent materials that can be very easily processed as monolith or film. Extensive structural characterization reveals that zirconia nanocrystals of 10-20 nm in size are efficiently dispersed into the hybrid matrix and that the local structure of the di-ureasil is not affected by the presence of the NPs. A significant enhancement in the refractive index of the di-ureasil matrix with the incorporation of the ZrO2 nanocrystals is observed. The optical study demonstrates that luminescent properties of both constituents are perfectly preserved in the final hybrid. Thus, the material displays a white-light photoluminescence from the di-ureasil component upon excitation at UV/visible radiation and also intense green and red emissions from the Er(3+)- and Yb(3+)-doped NPs after NIR excitation. The dynamics of the optical processes were also studied as a function of the lanthanide content and the thickness of the films. Our results indicate that these luminescent hybrids represent a low-cost, environmentally friendly, size-controlled, easily processed and chemically stable alternative material to be used in light harvesting devices such as luminescent solar concentrators, optical fibres and sensors. Furthermore, this synthetic approach can be extended to a wide variety of luminescent NPs entrapped in hybrid matrices, thus leading to multifunctional and versatile materials for efficient tuneable nonlinear optical nanodevices.

Eu3+-doped holmium aluminum garnet (Ho3Al5O12, HoAG) has been synthesized by a solvothermal method and annealed at various temperatures. The X-ray diffraction patterns confirmed that single-phase HoAG was obtained already at 220 °C.

Zirconia-mixed oxides can exhibit cubic fluorite and pyrochlore structure. Their discrimination is not easy in nanooxides with a crystal size close to that of a few unit cells. In this work, high resolution transmission electron microscopy (HRTEM) has been employed to provide key insights on the structural characterization of a nanometric and porous mixed Er 2 O 3 –ZrO 2 oxide. The material was prepared by a simple template-free solvothermal route that provided nanocrystalline powders at low temperature (170 °C) with spherical morphology, and high surface area (∼280 m 2 g −1 ). The porosity was mainly originated from the assembling of organic complexing agents used in the synthesis to limit the crystal growth and to control hydrolysis and condensation reaction rates. The samples were characterized by thermal analysis, X-ray diffraction, scanning electron microscopy and N 2 adsorption measurements. A detailed study by HRTEM was conducted on microtomed samples. It was observed that the material was made of nanocrystals packed into spherical agglomerates. HRTEM simulations indicated that it is not possible to identify the pyrochlore phase in nanoparticles with diameter below 2 nm. In our samples, the analysis of the HRTEM lattice images by means of fast Fourier transform (FFT) techniques revealed well defined spots that can be assigned to different planes of a cubic fluorite-type phase, even in the raw material. Raman spectroscopy was also a powerful technique to elucidate the crystalline phase of the materials with the smallest nanoparticles. HREM and Raman results evidenced that the material is constituted, irrespective of the temperature of the final calcination step, by an ensemble of randomly oriented nanocrystals with fluorite structure. This study opens new perspectives for the design of synthetic approaches to prepare nanooxides (fluorites and pyrochlores) and the analysis of their crystalline structure.

Research on organic–inorganic hybrid materials containing trivalent lanthanide ions (Ln3+) is a very active field that has rapidly shifted in the last couple of years to the development of eco-friendly, versatile and multifunctional systems, stimulated by the challenging requirements of technological applications spanning domains as diverse as optics, environment, energy, and biomedicine. This tutorial review offers a general overview of the myriad of advanced Ln3+-based organic–inorganic hybrid materials recently synthesised, which may be viewed as a major innovation in areas of phosphors, lighting, integrated optics and optical telecommunications, solar cells, and biomedicine.

Research on organic-inorganic hybrid materials containing trivalent lanthanide ions (Ln(3+)) is a very active field that has rapidly shifted in the last couple of years to the development of eco-friendly, versatile and multifunctional systems, stimulated by the challenging requirements of technological applications spanning domains as diverse as optics, environment, energy, and biomedicine. This tutorial review offers a general overview of the myriad of advanced Ln(3+)-based organic-inorganic hybrid materials recently synthesised, which may be viewed as a major innovation in areas of phosphors, lighting, integrated optics and optical telecommunications, solar cells, and biomedicine.

Today chemistry of materials and as such the ceramic field of research are addressed through more and more complex synthetic methodologies in order to optimize final material performances. The notion of complexity in chemical science is illustrated inhere through the concept of integrative chemistry. Particularly the integration between bi-liquid foams, sol-gel process, organo-silane functionnalization, lanthanides complexation and Pd heterogeneous nucleation is proposed as a non-exhaustive synthetic tool box to reach specific advanced ceramics. The first section is dealing with the synthesis of the first series of Si(HIPE) macrocellular foams where the oil volume fraction of the starting emulsion allows a nice tuning of the foams macroporosity. The second section is dealing with Europium complexation of diketone and malonamide hybrid Organo-Si(HIPE) leading to the Eu3+@Organo-Si(HIPE) luminescent foams, while the third part is dedicated to Pd heterogeneous nucleation within host hybrid foams. This last series of macrocellular ceramics are labeled Pd@Organo-Si(HIPE) which demonstrates good turn over number (TON) and turn over frequencies (TOF) when acting as supported catalysts for the Mizoroki-Heck coupling reactions. In the above mentioned foams the HIPE acronym is for High Internal Phase Emulsion.

An easy solvothermal route has been developed to synthesize the first mesoporous Er(2)O(3)-TiO(2) mixed oxide spherical particles composed of crystalline nanoplatelets, with high surface area and narrow pore size distribution. This synthetic strategy allows the preparation of materials at low temperature with interesting textural properties without the use of surfactants, as well as the control of particle size and shape. TEM and Raman analysis confirm the formation of nanocrystalline Er(2)O(3)-TiO(2) mixed oxide. Mesoscopic ordered porosity is reached through the thermal decomposition of organic moieties during the synthetic process, thus leading to a template-free methodology that can be extended to other nanostructured materials. High specific surface areas (up to 313 m(2) g(-1)) and narrow pore size distributions are achieved in comparison to the micrometric material synthesized by the traditional sol-gel route. This study opens new perspectives in the development, by solvothermal methodologies, of multifunctional materials for advanced applications by improving the classical pyrochlore properties (magnetization, heat capacity, catalysis, conductivity, etc.). In particular, since catalytic reactions take place on the surface of catalysts, the high surface area of these materials makes them promising candidates for catalysts. Furthermore, their spherical morphology makes them appropriate for advanced technologies in, for instance, ceramic inkjet printers.

Transition metal ions are usually incorporated as chromophores into pyrochlore structures in order to develop colored compounds. However, due to the high toxicity of some of them (Cr, Ni, Co, Cd …), other nontoxic species such as lanthanide ions have been studied in order to produce environment-friendly pigments. This paper describes the structural and spectroscopic study of a pink pigment based on the Er2Ti2−xZrxO7 system synthesized by a sol–gel route. A previous research on the Er2Ti2O7 system revealed that this compound exhibits a pink coloration only in its defect fluorite-type structure. At high temperature (800°C), an atomic rearrangement into a pyrochlore network significantly reduces its coloration. The stabilization of the fluorite phase in Er2Ti2O7 through substitution of Ti(IV) with larger Zr(IV) ions is studied in this work. The analysis by differential thermal analysis and thermogravimetric analysis, X-ray powder diffraction, and Raman techniques indicates that the introduction of Zr(IV) species successfully avoids the undesired fluorite-to-pyrochlore transition. The colorimetric study concludes that the optimal composition corresponds to the Er2Ti0.6Zr1.4O7 stoichiometry, which gives an intense pink coloration independently of the thermal treatment. This study introduces a novel nontoxic pigment suitable for industrial applications at both low- and high-temperature ceramic technologies.

This work aims the preparation of Eu:SrAl2O4 through a sol-gel methodology. Some studies point out the possibility that hexagonal polymorph exhibit higher luminescence efficiency than the monoclinic one. However, the slow diffusion processes in the solid-state reactions require the use of fluxing agents, like B(III) ions, to reduce the synthesis temperature, thus favouring the formation of the monoclinic phase and avoiding the stabilization of the hexagonal one. For that, the synthesis proposed in this work allows to prepare pure hexagonal and monoclinic polymorphs without the use of any fluxing agent. The influence of Eu-doping level and firing temperature in the crystalline structure and optical properties of both polymorphs are studied by means of X-ray diffraction, Raman scattering, absorption, excitation and emission spectroscopy. Emission spectra reveal the existence of energy transfer between the monoclinic matrix and the Eu2+ ion, but the luminescence efficiency is not influenced by the crystalline polymorph but it mainly depends on the firing temperature. © 2009 Elsevier B.V. All rights reserved.

13 pages; International audience; The elaboration of organosilica-based hybrid monoliths exhibiting a hierarchically structured bimodal porous structure with chelating functionality have been synthesized under interplay between high internal phase emulsion (HIPE) and lyotropic mesophases. For the first time grafted Eu3+@g -diketone-Si(HIPE) and Eu3+@gmalonamide-Si(HIPE) hybrid foams have been synthesized while a related Eu3+@ -diketone- Si(HIPE) material has been obtained under a one-step co-condensation process. The loading of monoliths with lanthanides was performed by impregnation of an europium(III) salt in solution. The resulting materials have been thoroughly characterized via a large set of techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), mercury porosimetry, nitrogen sorption isotherms, Fourier transform infrared (FTIR) spectroscopy, and 29Si and 13C magic angle spinning nuclear magnetic resonance (MAS NMR). This new series of luminescent Eu3+ containing Organo-Si(HIPE) materials has a large potential of promising applications in catalysis, optics, sensors, chromatographic supports, and so forth. For the first time, optical properties of these versatile materials with macro- and microporosity have been addressed thorough their absorption and emission spectra along with their relaxation luminescence properties.

Pyrochlore oxides show a large variety of physical and chemical properties depending on the ordering/disordering of the cations and oxygen vacancies. Taking account of these structural features and the luminescent properties of lanthanides, a new family of colored materials is investigated. This paper studies the structural evolution of the erbium titanate system with temperature to establish its influence on the color properties. The success on the development of color is completely related to the sol-gel preparation method, underlining its higher reactivity compared to classical solid-state synthesis. After firing at 700 degrees C, the sol-gel material develops an intense pink coloration whose intensity significantly diminishes at 800 degrees C. X-ray diffraction and Rietveld refinements indicated the presence of nanocrystals with a fluorite-like structure at 700 degrees C, responsible for the intense coloration, which suffers a gradual atomic rearrangement toward an "ideal" pyrochlore phase. These results were corroborated by infrared and Raman measurements. UV-vis spectroscopy showed the influence of the Er(3+)-O bond covalence on the spectral properties. This study opens new perspectives to the development of more ecological colored sol-gel materials based on rare earth elements. Furthermore, the combination of the optical aspects with the classical pyrochlore properties (magnetization, heat capacity, conductivity, etc.) would provide new multifunctional materials for advanced applications.

Research into lanthanide-doped organic–inorganic hybrid materials emerged in the 1990s with the development of interesting materials for optics: high efficiency and stable solid-state lasers, new fiber amplifiers and sensors, devices with upconversion, fast photochromic and non-linear responses, etc. Their interest relies on the possibility of combining properties of sol–gel host materials (shaping, tunable refractive index and mechanical properties, corrosion protection, specific adhesion, etc.) and the well-known luminescence of lanthanide ions (Ln). The fast development of photonic hybrids allowed the commercial exploitation of products with new or enhanced characteristics (megajoule pulsed Nd-YAG laser, protective coatings of glasses, screens or glasswares). However, recently, Ln-hybrid nanocomposites have found new applications in bio-sensors, bio-analytics and even clinical imaging diagnostics. These applications make use of the fluorescence properties of lanthanides that make luminescent hybrids ideal candidates for time-resolved fluoroimmunoassays, DNA hybridation assays, fluorescence imaging microscopy, or in vivo imaging. As a consequence, the goal of this review is twofold: (i) as a reminder of some general considerations that must be taken into account to design new optically active Ln-doped nanocomposites whatever the application field, and (ii) to show the most important advances achieved in the past years in different areas, paying special attention to bio-medical applications

10 pages; International audience; The elaboration of organo-silica-based hybrid monoliths exhibiting a hierarchical trimodal porous structure (micro-, synthesis, many organic functionalities that can act as network modifiers (methyl, dinitrophenylamino, benzyl, and mercaptopropyl) or co-network formers (pyrrol) have been anchored to the amorphous silica porous network. The resulting materials have been thoroughly characterized via a large set of techniques: SEM, TEM, SAXS, mercury porosimetry, nitrogen adsorption isotherms, FTIR, 29Si MAS NMR, and XPS. These sol-gel-derived hierarchical open-cell functional hybrid monoliths exhibit macroscopic void spaces ranging from 5 ím up to 30 ím and their accessible micro-and mesoporosities reveal hexagonal organization for the dinitrophenylamino-, benzyl-, and pyrrol-based hybrids. The average condensation degree for these hybrid networks ranges between 86 and 90%, yielding shaped monoliths with both good integrity and sufficient mechanical properties to be usable as functional catalytic or chromatographic supports. Also, function accessibility has been demonstrated through heterogeneous nucleation of Pd metallic nanoparticles.

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 9 nm, 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.

7 pages; International audience; The synthesis of novel meso-/macroporous SiO2 monoliths by combining a nano-building-blocks-based approach with the confined geometry of a tailored air-liquid foam structure is described. The resulting macrostructure in which ordered close-packed colloidal silica nanoparticles constitute the monolith's scaffolds very closely resembles the tailored periodic air-liquid foam template. The void spaces between adjacent particles create textural mesoporosity; therefore, the as-prepared silica networks are characterized by hierarchical porosity at the macroscopic and mesoscopic length scales. The fine-tuning of both the liquid foam's fraction and the bubble size allows a rational design over the macroscopic cell morphologies (shape, Plateau border's length, and width). Striking results of this approach are the weak shrinkage of the as-synthesized opal-like scaffolds during the thermally induced sintering process and, in contrast with previous studies, the formation of closed-cell structures. Particle organization and the foam film surface roughness are investigated by atomic force microscopy (AFM), showing the influence of the liquid flow, within the foams' Plateau borders and films, on the final assemblies.

Silica glasses containing both ZnS quantum dots (QDs) and luminescent lanthanide ions are attractive candidates to develop new lighting displays, sensor devices or laser emitters. This work reports an easy sol–gel method to prepare Eu3+-doped and Eu3+,Mn2+-codoped ZnS nanocrystals dispersed in a transparent silica matrix. Semiconductor nanocrystals with an average size of 5–6 nm and exhibiting both cubic and hexagonal phases were obtained at low temperature. The luminescent interactions between ZnS QDs, Eu3+ and Mn2+ ions provided materials with different optical responses but also gave information about the organization of the different species in the nanocomposite. Indeed, Eu ions were found to be both dispersed within the silica and located at the surface of the nanochalcogenide, the latter providing a ZnS/Eu3+ energy transfer. Incorporation of Mn2+ into the ZnS lattice induced the appearance of defect states that enhance the blue luminescence of the nanocomposite. These results underline the sensitivity of optical processes to the nature and organization of the active species, which is of vital importance for the design of photonic materials