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Scientific Papers in SCI



2020


Química de Superficies y Catálisis

Effect of Gold Particles Size over Au/C Catalyst Selectivity in HMF Oxidation Reaction

Megias-Sayago, C; Lolli, A; Bonincontro, D; Penkova, A; Albonetti, S; Cavani, F; Odriozola, JA; Ivanova, S
Chemcatchem, 12 (2020) 1177-1183

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A series of gold nanoparticles in the 4-40 nm range were prepared, immobilized on activated carbon and further tested, at low base concentration, in the catalytic oxidation of 5-hydroxymethyl furfural (HMF) to 2,5-furandicarboxylic acid (FDCA). Gold particles size variation has no influence on HMF conversion but significantly affects product selectivity and carbon balance. This behavior is ascribed to the thermodynamically favorable oxygen reduction reaction on Au(100) faces. As the gold particle size decreases the Au(100)/Au(111) exposure ratio, estimated by using the van Hardeveld-Hartog model, increases as well as the FDCA selectivity. The smaller the gold particle size the smaller the 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) to FDCA ratio pointing to the gold size dependent behavior of the oxidation of the alcohol function of the HMF molecule.


February, 2020 | DOI: 10.1002/cctc.201901742

Fotocatálisis Heterogénea: Aplicaciones

Evaluation of Au–ZnO, ZnO/Ag2CO3 and Ag–TiO2 as Photocatalyst for Wastewater Treatment

Murcia, J.J.; Hernández, J.S.;Rojas, H.; Moreno-Cascante, J.; Sánchez-Cid, P.; Hidalgo, M.C.; Navío, J.A.; Jaramillo-Páez, C.
Topics in Catalysis, (2020)

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In this work series of photocatalysts based on ZnO modified by Au and Ag2CO3 addition and Ag–TiO2 materials were synthesized and evaluated in the treatment of handicrafts factories wastewater and water samples taken from a highly polluted river. In general, it was found that ZnO series were more effective in the bacteria elimination than the commonly used TiO2 semiconductor. It was also observed that the metal (Au, Ag) or silver carbonate addition significantly increases the photocatalytic activity of ZnO and TiO2. It was determined that the content of the metal or carbonate added is an important factor to take into account in order to obtain suitable efficiency in the photocatalytic process, so, for example in the case of the river water samples the increase of Ag2CO3 content from 1 to 5%, had a detrimental effect over the bacteria elimination. The optimal conditions for dyes photodegradation and bacteria elimination were found by using a response surface study and the Au–ZnO (1%) photocatalyst. From this study it was determined that even after recycling this material leads to obtain a removal percentage of these pollutants over than 94%.


February, 2020 | DOI: 10.1007/s11244-020-01232-z

Fotocatálisis Heterogénea: Aplicaciones

Hybrid ZnO/Ag3PO4 photocatalysts, with low and high phosphate molar percentages

Martín-Gómez, A.N.;Navío, J.A.;Jaramillo-Páeza, C.;Sánchez-Cid, P.;Hidalgo, M.C.
Journal of Photochemistry and Photobiology A: Chemistry, (2020) 112196

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In this work, a previously optimized synthesized ZnO photocatalyst was modified with different molar percentages of Ag3PO4 through a facile in situ precipitation–deposition method and then characterized by different techniques (XRD, XRF, BET, UV–vis DRS, SEM, TEM and XPS). The incorporation of Ag3PO4 produces important changes in the light absorption properties with a significant absorbance in the visible region observed for ZnO modified with different amounts of Ag3PO4; the optical absorption intensity in the visible region of the coupled ZnO/Ag3PO4 increases as the molar percentages of Ag3PO4 increases, evidencing a clear dependence on the content of Ag3PO4. However, this work shows that the incorporation of Ag3PO4 in almost all cases reduces the photocatalytic capacity of ZnO, except when it is used in a specific percentage of 10 % and only being more active against rhodamine B and not on the Caffeine. SEM images and elemental mapping indicate that Ag3PO4 disperses very well in the ZnO particles, exhibiting an almost homogeneous distribution, showing zones with cumulus of Ag3PO4 (rich in P-Ag) in contact with ZnO-zones (rich in Zn). All the prepared photocatalysts were tested in the photocatalytic degradation of rhodamine B as a dye, and caffeine as a toxic and persistent emerging compound under UV and visible light illumination. It is reported that not only the ZnO:Ag3PO4 ratio is an important factor that influences the photocatalytic process of substrate degradation, but also the nature of the substrate has an important influence on the photocatalytic behavior of the materials under both UV and visible illumination. Thus, pristine Ag3PO4 showed high photocatalytic degradation for rhodamine B, while for caffeine negligible photocatalytic degradation was found in both the UV and visible regions. The thermal- and photo-stability of the coupled system was also studied. At least, for rhodamine B no loss of photocatalytic activity has been observed after five recycles although the mineralization degree progressively diminished along the recycles.


February, 2020 | DOI: 10.1016/j.jphotochem.2019.112196

Química de Superficies y Catálisis

Modulation of the acidity of a vermiculite and its potential use as a catalytic support

Amaya, J; Bobadilla, L; Azancot, L; Centeno, M; Moreno, S; Molina, R
Journal of Materials Science, 55 (2020) 6482-6501

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The modulation and characterization of the acidity of a vermiculite were carried out, which was modified by delamination by means of hydrothermal and acid treatments with the subsequent incorporation of AlZr and AlCe species to modulate the acidity. The effect of these species was evaluated regarding the structural (XRD, XPS and IR), textural (N-2 sortometry) and acidity properties (NH3-TPD, NH3-DRIFTS and CO adsorption at low temperature). The catalytic performance was studied in the dehydration-dehydrogenation reactions of 2-propanol and the hydroconversion of decane, which generate important information about the acidity properties such as the type, number and strength of acidic sites. The correlation between the number, type and acid strength with the catalytic behavior allowed to establish the important effect regarding the nature of the mineral, its method of delamination and the nature of the incorporated cation, thus generating tools for controlled processes for the potentiation of the acidity of new supports from raw vermiculite.


February, 2020 | DOI: 10.1007/s10853-020-04445-5

Nanotecnología en Superficies y Plasma

Robust label-free CuxCoyOz electrochemical sensors for hexose detection during fermentation process monitoring

Lopez-Fernandez, E; Gil-Rostra, J; Espinos, JP; Gonzalez, R; Yubero, F; de Lucas-Consuegra, A; Gonzalez-Elipe, AR
Sensors and Actuators B-Chemical, 304 (2020) 127360

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Label free electrochemical sensors of glucose are used whenever long-term operation and stable response are required. For this purpose, various metals and oxides of the first transition series have been proposed as alternative to more expensive noble metal electrochemical sensors. In this work we propose a new formulation consisting of copper-cobalt mixed oxides which, in the form of porous and nanostructured thin films with well controlled Co/Cu ratio, are prepared at room temperature in one step by a modification of the magnetron sputtering oblique angle deposition procedure. Films with various compositions were electrochemically characterized by cyclic voltammetry to determine their amperometric response to glucose as a function of voltage and NaOH electrolyte concentration. This analysis showed that films with a Co/Cu atomic ratio equal 3.4 presented a maximum sensitivity (0.710 A M−1 cm−2), a small limit of detection (0.105 μM) and a resilient behaviour upon cycling operation and long storage periods that clearly overpassed the performance of copper and cobalt single oxides. The CuxCoyO electrocatalysts also presented a good selectivity towards glucose and fructose in the presence of common interference compounds found in biological fluids (e.g., ascorbic acid, acetaminophen and uric acid), sucrose and ethanol, this latter present in many agrofood liquids. The possibilities of this sensor electrocatalyst have been tested for the analysis of a wine synthetic fermentation process. The comparison of the electrochemical results with conventional analytical methods showed a lineal amperometric response with respect hexose contents in a must at different stages of its transformation into wine.


February, 2020 | DOI: 10.1016/j.snb.2019.127360

 

 

 

 

 

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