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The design of molecular materials suitable for disparate fields could lead to new advances in engineering applications. In this work, a series of Ln3+-doped BiF3 sub-microparticles were synthesized through microwave-assisted synthesis. The effects of doping are evaluated from the structural and morphological viewpoint. In general, increasing the Ln3+ concentration the octahedral habitus is distorted to a spheric one, and some aggregates are visible without any differences in the crystalline phase. The optical response of the samples confirms that the BiF3 materials are suitable hosts for the luminescence of the tested trivalent lanthanide (Ln3+) ions (Ln = Eu, Tb, Tm, Ho, Er, Yb). A Yb3+/Er3+ co-doped sample is presented as an illustrative example of all-photonic molecular logic operations and primary luminescent thermometry.

Ceria-doped titania photocatalysts (ceria loading 0.25–5.0 wt%) were synthesized by hydrothermal methods for water remediation. Nanotubes (CeTNTx) and nanoparticles (CeTNPx) were obtained. Ceria doping was applied to tune the electronic properties of nanostructured titania, boosting its photocatalytic activity. CeTNT nanostructures contained anatase as the only titania phase, whereas the CeTNP series consisted of both anatase and rutile polymorphs. The Ce addition induced a decrease in the energy gap, allowing enhancement of visible light harvesting. The photodegradation of methylene blue, MB, in aqueous solution was chosen to study the influence of the morphology and the ceria loading on the photocatalytic response, under UV and solar light. Both CeO2–TiO2 nanoparticles and nanotubes were found to be very active under UV light. The highest MB degradation rates were obtained for the 0.25 wt% CeO2 doping, for both nanotubes and nanoparticles (0.123 and 0.146 min−1, respectively), able to photodegrade completely the dye after 120 min. The two samples are stable after a 3-cycle reusability test. The photo-response under simulated solar light confirmed that doping titania with ceria allows harvesting visible light absorption, enhancing its photoactivity. A maximum efficiency of 85% under simulated sunlight at a degradation rate of 0.054 min−1 was obtained. Transient photoluminescence confirmed that MB acts as a charge scavenger for the composite system. These results pointed out ceria-doped titania nanostructures as a promising class of photocatalysts for the degradation of dyes and other hazardous organic compounds in wastewater.

Massive quantities of spent coffee grounds (SCGs) are generated by users around the world. Different processes have been proposed for SCG valorization, including pyrolytic processes to achieve carbonaceous materials. Here, we report the preparation of activated carbons through pyrolytic processes carried out under different experimental conditions and in the presence of various porosity activators. Textural and chemical characterization of the obtained carbons have been achieved through Brunauer–Emmett–Teller (BET), ESEM, 13C solid state NMR, XPS, XRD, thermogravimetric and spectroscopic determinations. The aim of the paper is to relate these data to the preparation method, evaluating the correlation between the spectroscopic data and the physical and textural properties, also in comparison with the corresponding data obtained for three commercial activated carbons used in industrial adsorption processes. Some correlations have been observed between the Raman and XPS data.

We investigated the effect of copper doping on the photocatalytic properties of TiO2 thin films. Titania thin films doped with three different copper concentrations were synthesized via radiofrequency-assisted (RF) magnetron sputtering, then annealed at 600 °C in controlled atmosphere (Ar, O2, H2 flow). The impact of the annealing in inert, oxidizing or reducing atmosphere on the crystalline and surface structure, and photocatalytic performance in the methylene blue degradation under UV light irradiation was investigated by X-ray diffraction, UV–Vis Spectroscopy, Rutherford Backscattering Spectrometry, Scanning Electron Microscopy. Annealing induced very different crystallization in different atmospheres, with strong copper out-diffusion in samples annealed in reducing atmosphere and formation of large embedded nanoparticles. The Cu-doped titania films exhibited higher photocatalytic activity than pure titania film and the best performing catalyst, treated in H2 atmosphere, suggests that the presence of embedded copper nanoparticles (both metallic and oxidized) is able to strongly enhance the photocatalytic properties of the host titania matrix. Incorporated Cu particles can act as trapped sites for generated electrons, and this leads to the reduction of carrier recombination which, ultimately, plays a significant role in the increase of photoactivity. The recyclability of the best system was ascertained by a suitable 3-cycle stability test.

We investigated the photocatalytic behavior of gold nanoparticles supported on CeO2-TiO2 nanostructured matrixes in the CO preferential oxidation in H2-rich stream (photo-CO-PROX), by modifying the electronic band structure of ceria through addition of titania and making it more suitable for interacting with free electrons excited in gold nanoparticles through surface plasmon resonance. CeO2 samples with different TiO2 concentrations (0-20 wt %) were prepared through a slow coprecipitation method in alkaline conditions. The synthetic route is surfactant-free and environmentally friendly. Au nanoparticles (

During the last two decades, Dye Sensitized Solar Cells (DSSCs) have received a great deal of attention as a promising, low-cost alternative to conventional silicon photovoltaic devices. Natural dye molecules can be used as a sensitizer for their low cost, good light absorbance, easy preparation process, and biodegradability. In this study, dyes were obtained from wine lees, the last by-product of winemaking process, supplied by a venetian winery (Italy). Polyphenols, like tannins and anthocyanins, which were extracted from winemaking lees, were adsorbed on a nanostructured ordered mesoporous titanium dioxide, previously treated at different temperatures (400&ndash, 600 &deg, C). Both dyes and titania semiconductor samples were studied with different techniques. The tests were carried out on prototypes to evaluate the cell power and the photocurrent generated under simulated solar light irradiation. The obtained solar energy conversion efficiencies are comparable to those that were reported in literature by using organic dyes extracted from vegetables, fruits, and plants. It is significant that these dyes are largely available and cost effective, since recovered from a waste otherwise to be disposed of, opening up a perspective of feasibility for inexpensive and environmentally friendly dye solar cells to generate green electricity and transforming agri-food waste into a resource.

A new synthesised triphenylamine-based dye having a branched structure with one OH-ending branch able to interact with the surface hydroxyl moieties of mesoporous TiO2 is reported. Optical properties of the dye-titania hybrid material are presented and the higher efficiency of the dye on pure anatase TiO2 compared to the commercial Degussa P25, which contains a rutile phase component, is confirmed. The optical and chemical properties of the dye make it a promising candidate as a metal-free dye for DSSCs or as a host for a variety of transition or main group metal ions for different applications.

A Cu/CeO2/Al2O3 catalyst prepared by a single-step sol–gel method was studied for methanol steam reforming (SRM) to gain information on the oxidation state of Cu and the role of oxidized Cu species. The catalyst was tested in a new laboratory-made flow apparatus that allowed on-line analysis of the products and measurement of the oxidation state and dispersion of Cu in situ. The catalyst pre-reduced in H2 was more active and selective than the not pre-reduced one. The oxidation state, evaluated after SRM tests, suggested the presence of a layer of oxygen atoms on the metallic Cu surface. Treating the pre-reduced catalyst with H2O vapour at 250 °C caused dissociative H2O chemisorption and led to a partial oxidation of Cu. The H2O oxidized sample reacted with CH3OH producing CO2 and H2 as long as oxygen was present on the Cu surface. The results support an oxidation–reduction mechanism.

Ce–Zr–Cu mixed oxide systems, with different contents of ZrO2 and CuO, were prepared by slow co-precipitation method, leading to the formation of materials with a flower-like morphology. It was evaluated both the role of CuO loading (3–7 wt%), by maintaining constant the amount of ZrO2 (7 wt%), and the role of ZrO2 (2–10 wt%) with a fixed amount of CuO (7 wt%). The prepared catalysts were characterized by means of ICP-OES, SEM, N2 physisorption, quantitative XRD, H2-TPR, and XPS. Their catalytic performances in the preferential oxidation of CO in excess of H2 (CO-PROX) were evaluated, in the 40–190 °C temperature range. Characterization and catalytic results showed that an optimum Zr/Ce molar ratio and CuO loading are required to attain the best catalytic performance over the studied nanostructured Ce/Zr/Cu oxide system. Characterization results revealed that, regardless of the sample composition, all of them presented similar flower-like morphology and textural properties. Instead, the catalyst composition determined the crystalline phases formed, their reducibility and surface distribution. The catalyst containing an intermediate ZrO2 loading (7 wt%) and the highest studied CuO amount (7 wt%), FCZCu77, showed the higher fraction of undetectable CuO from XRD, that is the highest proportion of highly dispersed Cu species also observed from H2-TPR. These characteristics justify how FCZCu77 catalyst exhibited a quite higher catalytic activity than the others samples.

Ordered mesoporous silica nanoparticles (MSNs) were impregnated with different loadings of the luminescent complex tris(dibenzoylmethane) mono(1,10-phenanthroline)europium(III) (Eu(dbm) 3 phen), with the aim of increasing the luminescence by avoiding concentration quenching and having mainly in mind the application as spectral converter for multi-crystalline silicon solar cells. The morphological, structural and luminescence properties of the impregnated silica nanoparticles were characterized by N 2 physisorption, X-ray diffraction, transmission electron microscopy, infrared spectroscopy, UV–visible spectroscopy and photoluminescence excitation and emission measurements. Photostability was tested under 1 sun (1000 W/m 2 ) illumination for 24 h and the related effects were inspected by UV–visible and photoluminescence spectroscopies. Impregnation of the complex into 50–70 nm MSNs with pore size tailored around 2.9 nm depressed concentration quenching and allowed the use of complex loadings as high as 23 wt%. Sunlight irradiation caused a marked increase in the luminescence intensity.

a b s t r a c t Nanocrystalline CeO2 with a regular size of 9.5 nm was prepared by a freeze-drying method, and subse- quent impregnated with a Cu(II) acetate solution, varying the loading of Cu (3, 6, 12 wt.%). The resulting CuO/CeO2 materials were characterized by N2 physisorption at −196 ◦ C, HRTEM, H2-TPR, X-ray diffrac- tion, Raman spectroscopy and XPS and tested as catalysts in the preferential CO oxidation in a H2-rich stream (CO-PROX) in the temperature range 40-190 ◦ C. In spite of their low specific surface areas the cat- alysts exhibited a good catalytic performance, resulting active and selective in the CO-PROX reaction at low temperatures. The inhibiting effect of the simultaneous presence of CO2 (15 vol.%) and H2O (10 vol.%) in the reaction mixture on the performance of CuO-CeO2 catalysts was also investigated. The addition of CO2 and water in the gas stream depressed CO oxidation up to 160 ◦ C, its effect being negligible at higher temperatures. Nevertheless, despite these expected deactivation phenomena, a CO conversion value higher than 90% and a CO2 selectivity of about 90% was achieved for all the samples at 160 ◦C. The excellent performance, especially shown by the catalyst with 6 wt%. of copper, has been related to the wide dispersion of the copper active sites associated with the high amount of Ce4+ species before reaction.

Ce–Cu and Ce–Zr–Cu oxide systems with a flower-like morphology were prepared by slow co-precipitation in the absence of any structure directing agent. For the sake of comparison, Ce–Cu and Ce–Zr–Cu oxide samples were also prepared by a classic co-precipitation method. All the samples were calcined in air flow at 650 °C. The materials were characterized by SEM and TEM microscopy, quantitative X-ray diffraction, N2 physisorption, H2-TPR, O2-TPD and XPS. The catalytic activity of the prepared samples was evaluated in the preferential oxidation of CO in excess of H2 (CO-PROX), in the 40–190 °C temperature range., The authors wish to thank Martina Marchiori (Ca’ Foscari University – Venice) for N2 physisorption and TPR-TPO measurements and Dr. Davide Cristofori (Ca’Foscari University-Venice) for the HRTEM measurements.

In this article, the preparation and application of gold and cerium catalysts supported on zirconium-doped mesoporous silica SBA-15 was studied. These materials have been prepared by two different methods and characterized to investigate their textural properties, dispersion of the active phases and oxidation states. Both materials exhibit a marked catalytic activity. The size of the gold nanoparticles is directly related to the CO conversion rate and to the selectivity towards CO 2 exhibiting a strong temperature dependence. An X-ray photoelectron spectroscopic study of the composition and chemical state of the nanoparticles indicates the presence of Au in a metallic state. Transmission electron microscopic micrographs indicate that the best catalyst shows a higher dispersion of Au in spite of its lower gold surface content.

A Ce-Zr-Cu oxide system with a flower-like morphology was prepared by a slow co-precipitation method in the absence of any structure directing agent. Four portions of the oxide were thermally treated at four different temperatures (350°C, 450°C, 550°C, 650°C). The resulting materials samples were characterized by quantitative XRD, adsorption-desorption of N2 at-196°C, SEM and TEM microscopy, -H2-TPR, XPS and Operando-XANES. All samples were tested in the preferential CO oxidation (CO-PROX) in the 40-190°C temperature range. Thermal treatments were found to induce slight structural changes without altering the starting morphology of the samples. The samples treated at higher temperature 550-650°C showed a quite interesting CO-PROX activity and selectivity in a temperature range suitable for a practical use within the FEMFC technology. © 2011 Elsevier B.V.

A mesoporous Cu-Ce-Al-based material was prepared by a single-step synthesis, performed in n -propanol using aluminum sec -butoxide as Al precursor and metal stearates, both as Cu-Ce sources and structural directing agents. This type of synthetic approach appears to be very efficient for the preparation of highly dispersed Cu-Ce containing particles supported on a structurally ordered alumina with high surface area (>400 m 2 g −1 ) and quite narrow pore size distribution, as confirmed by X-ray powder diffraction, TPR and dispersion data and N 2 physisorption. The catalyst was also characterized by XPS and FT-IR measurements of adsorbed CO. The catalytic activity for the preferential oxidation of CO to CO 2 (PROX) in H 2 -rich streams was tested in the 75–200 °C temperature range.

Various samples of the Al–Ce–Cu ordered mesoporous oxide system were prepared by a single-step synthesis using n-propanol as solvent, aluminum sec-butoxide as Al precursor, metal stearates and/or metal nitrates as Cu and Ce sources. Different reagent types and reagents ratios were used in order to explore the role of these synthetic parameters in determining the chemical, textural and structural properties of the resulting materials. The study was carried out using nitrogen physisorption at 77 K, X-ray powder diffraction (XRPD), temperature-programmed reduction (H2-TPR), temperature-programmed desorption of ammonia (NH3-TPD) and FT-IR spectroscopy of adsorbed pyridine.

A series of CuO-ZnO/TiO2 ternary catalysts was prepared by co-precipitation and characterized by X-ray powder diffraction (XRPD), N2 physisorption at 77 K, temperature-programmed reduction/oxidation (H2-TPR/TPO) and FT-IR measurements of low temperature adsorbed CO. The catalysts were tested and found active in the preferential oxidation of CO (CO-PROX) in hydrogen-rich gas streams and their catalytic performance was compared with that of the binary systems CuO/ZnO and CuO/TiO2. © 2008 Elsevier B.V. All rights reserved.

An Al/Ce/Mg=50.0/1.0/1.0 atomic ratio (a.r.) pillared montmorillonite was used to support 1.0 wt.% of the bimetallic species Pd/Pt=5.0 and Pd/Au=5.0 a.r. The resulting catalysts were characterized by XRPD, N2 physisorption, ammonia TPD and FT-IR spectroscopy. The catalytic activity in the hydrogenation and hydrogenolysis/ring-opening of naphthalene and thio-tolerance to dibenzothiophene were investigated at 6.0 MPa in a flow reactor. Both catalysts showed interesting performances. Of the two catalysts, the former showed higher productivities in hydrogenation and hydrogenolysis/ring-opening compounds together with lower losses in carbon balance and higher thio-tolerance. These results not only confirmed that Pd/Pt is one of the most suitable bimetallic pair for noble metal containing hydrotreating catalysts, but also that the Al/Ce/Mg PILC can be used as low cost support for noble-metal-containing active phases.

Synthetic smectites framework substituted with Ti, Fe, and Zn were synthetized in hydrothermal conditions. The materials were characterized by XRD, nitrogen adsorption, MAS-NMR. FT-IR spectroscopy of adsorbed pyridine and analysis of product distribution in the 1-butene isomerization was used to evaluate the surface acidity. Chemical properties were correlated to the nature and presumed lattice location of the framework substituents.