Designing Ln3+-doped BiF3 particles for luminescent primary thermometry and molecular logic

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.publishe

Au and AuCu nanoparticles supported on SBA-15 ordered mesoporous titania-silica as catalysts for methylene blue photodegradation

The photocatalytic degradation of methylene blue (MB) dye has been performed under UV irradiation in aqueous suspension, employing photocatalysts based on Au (1.5 wt %) and AuCu (Au/Cu = 1, 2.0 wt %), and supported on SBA-15-ordered mesoporous silica, with and without titania (Si/Ti = 3), in order to evaluate the versatility of this mesoporous support in this type of reaction of great impact from the environmental point of view. Samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption at −196 ◦C, and X-ray photoelectron spectroscopy (XPS), so as to study their structural, optical, and chemical properties. All the prepared catalysts were found to be active in the test reaction. The bimetallic AuCu-based catalysts attained very high MB degradation values, in particular AuCu/SBA-15 titania-silica sample reached 100% of dye oxidation after the monitored reaction period (120 min)

Importancia de la morfología de estructuras de ceria-titania en la fotodegradación de azul de metileno bajo UV y luz solar simulada

La contaminación del agua constituye un problema de alcance mundial hoy día cuyos efectos perjudiciales se manifiestan tanto a corto como a largo plazo. De entre todas las fuentes antropogénicas de polución del agua, se estima que alrededor del 20 % proviene de la industria textil, que descarga grandes cantidades de efluentes conteniendo colorantes orgánicos e inorgánicos que pueden afectar a los ecosistemas marinos y a la salud humana. Tradicionalmente, la adsorción ha sido la técnica más empleada para la eliminación de estos colorantes de los efluentes acuosos, sin embargo, esta tecnología no permite la degradación de estos. Es por ello que la comunidad científica busca desarrollar metodologías más efectivas para este fin, como son los procesos de oxidación avanzados (AOPs) que permiten utilizar la radiación UV y visible para producir especies con alto poder oxidativo, como los radicales hidroxilo. La titania, TiO2, se presenta como el fotocatalizador más efectivo en procesos AOPs, pero su amplio band gap (3.2 eV) requiere el uso de radiación UV, que solo comporta el 5% de la radiación solar incidente. Con el objeto de ampliar el rango de operación al visible, la titania puede doparse con metales nobles que presenten actividad fotocatalítica, como el oro, o con óxidos reducibles que presentan gran capacidad redox. En este trabajo se ha estudiado la influencia de la adición de ceria, CeO2, en nanoestructuras de titania con diferente morfología, nanotubos y nanopartículas, en la fotodegradación de azul de metileno bajo radiación UV y bajo luz solar simulada.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

CO preferential photo-oxidation in excess of hydrogen in dark and simulated solar light irradiation over AuCu based catalysts on SBA-15 mesoporous silica-titania

In this work, SBA-15 silica and silica-titania have been used as supports for photocatalysts based on AuCu alloy (Au:Cu = 1) to be used in the preferential oxidation of CO (CO-PROX) in excess of hydrogen at room temperature and atmospheric pressure both in the dark and under simulated solar light irradiation. To study their textural, structural, chemical and optical properties, the samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), adsorption-desorption of N2 at 196 C, 13C and 29Si solid state nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance ultraviolet-visible (DRUV-vis) spectroscopy. Titanium was present mainly in the form of titania aggregates, but also as small particles interacting with the SBA support. In both catalysts, the metal alloy nanoparticles displayed an average size of 4 nm as demonstrated by TEM measurements. AuCu/Ti-SBA turned out to be photoactive and selective in the photo-CO-PROX reaction showing the highest activity, with conversion and selectivity towards CO2 of 80%, due both to the presence of titania incorporated in SBA-15 and to the synergistic effect of Cu when alloyed with Au

Novel Correlations between Spectroscopic and Morphological Properties of Activated Carbons from Waste Coffee Grounds

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

Photocatalytic performance of Cu-doped titania thin films under UV light irradiation

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

PROCEDIMENTO PER LA REALIZZAZIONE DI CELLE FOTOELETTROCHIMICHE CON L\u2019UTILIZZO DI COLORANTI ESTRATTI DA RESIDUI DI VINIFICAZIONE

La presente invenzione riguarda un procedimento per la realizzazione di celle fotoelettrochimiche con l\u2019utilizzo di coloranti estratti da residui di vinificazione. L\u2019invenzione riguarda anche i coloranti ottenibili con il suddetto procedimento di estrazione e le celle fotoelettrochimiche realizzate con tali coloranti

Nanostructured CeO2-TiO2 for the photodegradation of Methylene Blue

In the latest years environmental protection and use of renewable energy sources are two major objectives in chemical research. Solar energy can be exploited for the photocatalytic degradation of organic molecules such as pollutants, hormones or drugs in air, water and surfaces because sunlight is able to decompose them [1]. Despite of the huge number of applications of titania (TiO2), a no-toxic, low cost and very promising photocatalyst [2], there are some critical factors that limit its photoactivity, first of all the fact that titania is a semiconductor only active in the UV region of the light spectrum. Several methods have been proposed to reduce its energy-gap value, among which noble metal deposition, surface modifications and doping with transition metal ions or rare earth elements. CeO2 has attracted great attentions due to its unique properties, such as biocompatibility, chemical inertness and strong oxidizing capability related to the formation of oxygen defects [3]. CeO2-TiO2 systems seem to exhibit improved photocatalytic activity due to the enhanced mobility of excitons and/or reduced band gaps. In the present work, nanostructured TiO2 with different CeO2 loadings were synthesized with a two-step hydrothermal route, the first one being a sol-gel process and the second one a dehydration with NaOH. CeO2-TiO2 samples were characterized by many techniques. Surface and bulk chemistry was evaluated using X-ray diffraction (XRD) and X-ray photoelectron Spectroscopy (XPS); morphological and textural characterization was carried out by high resolution transmission electron microscopy (HRTEM); porosity was measured by N2 physisorption. Cerium-doped TiO2 samples displayed a methylene blue (MB) degradation rate in aqueous suspension under UV light higher than that of pure TiO2, since the introduction of cationic ceria dopant led to the decrease of band gap energy, as found by DRIFT UV-vis spectroscopy (from 3.2 eV to about 2.8 eV). The CeO2-TiO2 photocatalysts were found active in the test reaction attaining very high MB degradation values of dye oxidation after the monitored reaction period (120 min)

3-D flower like Ce-Zr-Cu mixed oxide systems in the CO preferential oxidation (CO-PROX): Effect of catalyst composition

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 (3-7wt%), by maintaining constant the amount of ZrO2 (7wt%), and the role of ZrO2 (2-10wt%) with a fixed amount of CuO (7wt%). 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 (7wt%) and the highest studied CuO amount (7wt%), 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.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 (3-7wt%), by maintaining constant the amount of ZrO2 (7wt%), and the role of ZrO2 (2-10wt%) with a fixed amount of CuO (7wt%). 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 (7wt%) and the highest studied CuO amount (7wt%), 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