http://hdl.handle.net/10366/4164 2026-05-02T22:21:03Z 2026-05-02T22:21:03Z Puerto-Jiménez, María Bu, Enqi Goma Jiménez, Daniel Aguinaco, Almudena Delgado, Juan José Pintado, José María Blanco, Ginesa Bogeat Barroso, Adrián http://hdl.handle.net/10366/170978 2026-04-14T10:40:16Z 2026-03-11T00:00:00Z

[EN]The development of efficient visible light photocatalysts based on ceria (CeO2) requires precise control over both morphology and electronic band structure. Herein, a facile one-pot hydrothermal method is reported for the preparation of crystallographically well-defined ceria nanocubes featuring enhanced photocatalytic response under visible light irradiation. The proposed approach relies on the in situ structural incorporation of 1,10-phenanthroline during crystal growth. Unlike conventional doping or surface functionalisation strategies, this method yields organic–inorganic nanostructured hybrid materials where the organic moiety is effectively incorporated into the fluorite-type ceria lattice through the formation of Ce–N coordination bonds while preserving the cubic morphology enclosed by reactive {100} facets and simultaneously increasing the specific surface area. Diffuse reflectance UV–Vis spectroscopy and valence band XPS analyses reveal that this integration induces the appearance of N 2p intraband gap states associated with the Ce–N bonds, resulting in a significant narrowing of the optical band gap and extending the light absorption edge into the visible region. Consequently, these organoceria hybrids exhibit a remarkable synergistic enhancement in photocatalytic hydrogen production via ethanol photoreforming under simulated solar irradiation, with hydrogen evolution rates being 7.5 times higher than those of pristine ceria nanocubes. This work demonstrates the potential of organic ligand-assisted lattice engineering as a versatile approach for tailoring the optoelectronic properties of ceria, thus opening new avenues for sustainable solar-to-chemical energy conversion.

2026-03-11T00:00:00Z Cavaliere, Sara Jiménez Morales, Ignacio Ercolano, Giorgio Savych, Iuliia Jones, Deborah Rozière, Jacques http://hdl.handle.net/10366/168599 2026-01-10T01:02:45Z 2015-01-01T00:00:00Z

[EN]High durability and activity for the oxygen reduction reaction were demonstrated for oxide-supported platinum catalysts. The supports were antimony-doped SnO2 (ATO) fibres-in-tubes obtained by electrospinning and subsequent calcination. The doping with antimony instead of the already-reported niobium, allowed the preparation of tin oxide with electrical conductivity that was similar to carbon, which also had an increased electrocatalyst loading. Platinum nanoparticles supported on electrospun ATO demonstrated higher electrochemical stability and comparable mass activity to commercial Pt/C during exsitu potential cycling. The in situ fuel cell tests also revealed improved corrosion resistance with no noticeable degradation of the oxide-based membrane electrode assembly (MEA), but a slightly lower performance compared to the MEA with carbon-supported catalysts.

2015-01-01T00:00:00Z Larsen, Mikkel Juul Jiménez Morales, Ignacio Cavaliere, Sara Zajac, Jerzy Jones, Deborah J. Rozière, Jacques Kaluža, Luděk Gulková, Daniela Odgaard, Madeleine http://hdl.handle.net/10366/168597 2026-01-10T01:02:36Z 2017-01-01T00:00:00Z

[EN]A family of novel carbon materials with intermediate surface area and varying morphology and surface chemistry were used to prepare Pt/C catalysts by two different preparation procedures; a chemical impregnation method and a microwave-assisted polyol method. The catalysts were thoroughly characterized, and their electrochemical performance and stability were investigated with rotating disc electrode (RDE) cyclic voltammetric (CV) measurements. The intermediate-surface-area carbon supports gave catalysts with much greater support stability than a widely used standard catalyst. The novel catalysts had lower electrochemical surface area than the reference, but their specific electrocatalytic activity towards the oxygen-reduction reaction (ORR) was much higher, and some of them also featured higher mass-specific ORR activity than the reference. The series of catalysts prepared by the microwave-assisted polyol method featured smaller Pt nanoparticles and higher activities than those prepared by impregnation. On the other hand, the impregnated catalysts showed better durability of the Pt particles. The most promising catalysts were selected and elaborated in further optimized preparation procedures to obtain quantities sufficient for their use in proton-exchange membrane fuel cells (PEMFCs).

2017-01-01T00:00:00Z Jiménez Morales, Ignacio Haidar, Fatima Cavaliere, Sara Jones, Deborah Rozière, Jacques http://hdl.handle.net/10366/168596 2026-01-10T01:01:56Z 2020-01-01T00:00:00Z

[EN]Electrocatalyst supports stable to high potential are required for the proton exchange membrane fuel cell cathode. Electrocatalyst supports based on tantalum-doped tin oxide (Ta/SnO2) were prepared by electrospinning. The dopant amount was varied between 0 (undoped SnO2) and 7.5 at. %, and the resulting materials were characterized for their morphology, composition, structure, porosity, and electrical properties. Platinum nanoparticles prepared by a microwave-assisted polyol method were deposited with different loadings on 1 at. % Ta-doped SnO2 (1Ta/SnO2), selected for its highest electrical conductivity of 0.09 S cm–1. Their electrocatalytic properties toward the oxygen reduction reaction (ORR) were compared with those of the same particles deposited on carbon black and those of a commercial carbon-supported Pt catalyst. Pt/1Ta/SnO2 showed higher ORR activity and stability at high potential than Pt/C. In particular, the electrocatalyst with the lowest Pt loading (7 wt %) presented high mass activity and stability which, from XPS analysis, is suggested to result from very strong metal–support interaction. These results indicate that amongst tin oxides doped with pentavalent metals such as niobium (Nb/SnO2), antimony (Sb/SnO2), and tantalum, Ta/SnO2 has the advantage of both higher conductivity than Nb/SnO2 and greater stability in the fuel cell voltage range than Sb/SnO2.

2020-01-01T00:00:00Z Rodríguez-García, Bárbara Reyes-Carmona, Álvaro Jiménez Morales, Ignacio Blasco-Ahicart, Marta Cavaliere, Sara Dupont, Marc Jones, Deborah Rozière, Jacques Galán-Mascarós, José Ramón Jaouen, Frédéric http://hdl.handle.net/10366/168595 2026-01-10T01:01:54Z 2018-01-01T00:00:00Z

[EN]This study investigates the activity and stability of a Prussian blue analogue (PBA) as an inexpensive anode catalyst for Polymer Electrolyte Membrane Water Electrolysis (PEMWE). While some PBAs have recently been reported to catalyze the oxygen evolution reaction (OER) in acidic electrolytes, the present study focuses on their integration in a PEMWE device. Cobalt hexacyanoferrate nanoparticles were interfaced with an electrically conductive support that withstands the PEMWE anodic conditions, namely Sb-doped SnO2. The OER activity of the composite materials was first verified in liquid electrolytes and then in PEMWE. A promising current density of 50–100 mA cm−2 was reached at 2 V cell voltage. The PBA/Sb–SnO2 anode was stable up to 1.9 V, but showed more and more instability at higher potentials. Increasing leaching rates of Sn and Sb observed above 1.9 V suggest that the material instability above 1.9 V can mainly be assigned to Sb-doped SnO2 conductive support. These results are overall promising for the use of PBAs as catalytic sites at the anode of PEMWE. The study also identifies the need for more active PBAs in order to reach a higher current density at a cell voltage of 1.6–1.9 V, a potential range necessary for an acceptable energy efficiency of the PEMWE.

2018-01-01T00:00:00Z Jiménez Morales, Ignacio Cavaliere, Sara Dupont, Marc Jones, Deborah Rozière, Jacques http://hdl.handle.net/10366/168594 2026-01-10T01:01:53Z 2019-01-01T00:00:00Z

[EN]The electrocatalyst support antimony doped tin oxide (ATO) was investigated at low and high potentials with ex situ and in situ electrochemical techniques to assess its stability in proton exchange membrane fuel cell (PEMFC) and water electrolysis (PEMWE) operating conditions.

2019-01-01T00:00:00Z Jiménez Morales, Ignacio Cavaliere, Sara Jones, Deborah Rozière, Jacques http://hdl.handle.net/10366/168592 2026-01-10T01:02:44Z 2018-01-01T00:00:00Z

[EN]Niobium and antimony doped tin oxide loose-tubes decorated with Pt nanoparticles present outstanding mass activity and stability, exceeding those of a reference carbon-based electrocatalyst. Physico-chemical characterisation and in particular X-ray photoelectron spectroscopy demonstrate that this observation can be ascribed to the strong metal–support interaction promoting electroactivity and Pt anchoring on doped metal oxide supports.

2018-01-01T00:00:00Z Jiménez Morales, Ignacio Moreno-Recio, M. Santamaría-González, J. Maireles-Torres, P. Jiménez-López, Antonio http://hdl.handle.net/10366/168523 2026-01-09T01:02:14Z 2015-01-01T00:00:00Z

[EN]Mesoporous aluminium doped MCM-41 silica catalysts were prepared by a sol–gel method in two reaction steps (acid and alkaline hydrolysis) from joint hydrolysis of tetraethylortosilicate (TEOS) and aluminium triisoproxide, using n-dodecylammonium chloride as surfactant, at room temperature, and subsequent calcination at 550 °C. Two solids with different Si/Al molar ratios (5 and 10) were synthesized, which possess high specific surface area and acidity, with both Brönsted and Lewis acid sites. By using a biphasic water/MIBK as reaction medium and a 30 wt.% of the 10Al-MCM catalyst with respect to the substrate weight (glucose), 87% of glucose conversion and 36% of HMF yield were achieved at 195 °C after 150 min of reaction time. The reaction is quite selective toward HMF, since only fructose was detected as by-product, but neither levulinic acid nor furfural were found. Moreover, the use of a sodium chloride aqueous solution (20 wt.%) and MIBK ameliorates the partition coefficient between the organic and the aqueous phases up to 1.9, leading to an enhancement of the glucose conversion and HMF yield, attaining values of 98% and 63%, respectively, in a time as short as 30 min. The catalytic performance of this acid solid, associated to the presence of strong acid sites, is well maintained after three catalytic cycles.

2015-01-01T00:00:00Z Bogeat Barroso, Adrián Alexandre-Franco, María Fernández-González, Carmen Gómez-Serrano, Vicente http://hdl.handle.net/10366/167189 2025-09-26T00:01:54Z 2025-09-22T00:00:00Z

[EN]The present work is aimed at shedding light on the evolution of surface chemistry of a commercial activated carbon (AC) support during the preparation of supported metal oxide (MO) catalysts by the conventional wet impregnation method. Particular attention is paid to the chemical changes of oxygen-containing surface functionalities across three preparation stages of impregnation, oven-drying, and thermal treatment. AC was impregnated with aqueous solutions of several MO precursors (Al(NO3)3, Fe(NO3)3, Zn(NO3)2, SnCl2, and Na2WO4) at 80 °C for 5 h, oven-dried at 120 °C for 24 h, and heat-treated at 200 °C and 850 °C for 2 h under an inert atmosphere. The surface chemistry of the resulting catalyst samples, classified in three series by the thermal treatment, was mainly studied by FT-IR spectroscopy, complemented by elemental analysis and pH of the point of zero charge (pHpzc) measurements. During impregnation, phenolic hydroxyl and carboxylic acid groups were predominantly formed by wet oxidation of chromene, 2-pyrone, and ether-type structures found in the pristine AC. The extent of these oxidations correlated with the oxidising power of the precursor solutions. As expected, thermal treatment at 850 °C brought about markedly stronger chemical changes, with most of the above oxygen functionalities decomposing and forming less acidic structures, such as 4-pyrone groups, metal carboxylates, and C-O-M atomic groupings. All these surface chemical modifications result in a lowering of the strong basicity of the raw carbon support (pHpzc ≈ 10.5), thus leading to pHpzc values for the catalysts widely ranging from 1.6 to 9.7.

2025-09-22T00:00:00Z Górtazar, Guillermo Fernández-González, Darío Montoro, Carmen Romero, Jorge F. Dafinov, Anton Jiménez, Alejandro Jiménez Morales, Ignacio Bogeat Barroso, Adrián Zamora, Félix García Álvarez, Mayra López Maya, Elena http://hdl.handle.net/10366/165934 2026-01-14T13:18:42Z 2025-01-01T00:00:00Z

[EN]Herein, we report the first example of MOF synthesis employing aluminum slags as a waste resource. This synthesis was exclusively carried out from waste materials, under ambient conditions in water, thus aligning with the guiding principles of Green Chemistry. The resulting MIL-53(Al) material was further functionalized with SnO2 nanoparticles and tested as catalyst for the dehydration of glucose to 5-hydroxymethylfurfural (5-HMF), showing a tenfold increase in catalytic efficiency compared to unsupported SnO2

2025-01-01T00:00:00Z Jiménez Morales, Ignacio del Río-Tejero, M.A. Braos-García, P. Santamaría-González, J. Maireles-Torres, P. Jiménez-López, A. http://hdl.handle.net/10366/163123 2025-04-30T19:50:48Z 2012-01-01T00:00:00Z

[EN]Stable sulfated zirconia can be prepared by impregnation with sulfuric acid of a zirconium doped mesoporous MCM-41 silica and ulterior calcination at 750 °C. Two catalysts with nominal sulfur contents of 1.3 and 4 wt.% were prepared. After the thermal activation at this temperature, some sulfate ions (sulfur content of 0.15 and 0.69 wt.%) are strongly retained onto the superficial zirconia, thus generating acidic catalysts which are able to produce the esterification of oleic acid with methanol at 75 °C in 5 h. The experimental results reveal that the unique way to obtain stable catalysts without leaching of sulfate species to the liquid medium of reaction is by thermal treatment at high temperature as 750 °C. Only with 1 g of this stable catalyst a conversion close to 98% was attained. The conversion of this catalyst is well maintained in a high extend (76%) after three cycles of catalysis without any treatment and is stable in the presence of 5 wt.% of water.

2012-01-01T00:00:00Z Jiménez Morales, Ignacio Moreno-Recio, M. Santamaría-González, J. Maireles-Torres, P. Jiménez-López, A. http://hdl.handle.net/10366/163121 2025-04-30T19:50:48Z 2014-01-01T00:00:00Z

[EN]Mesoporous tantalum oxide was prepared by acid hydrolysis of tantalum penta-ethoxide in the presence of a triblock co-polymer Pluronic L-121, a non-ionic surfactant, at room temperature and subsequent calcination at 550 °C for 6 h. This solid exhibits a suitable specific surface area (79 m2 g−1) and a high acidity (353 μmol NH3 g−1) with the presence of both Brönsted and Lewis acid sites, demonstrating to be active as solid acid catalyst in the dehydration of glucose to 5-hydroxymethylfurfural (HMF), in a biphasic water/methyl-iso-butyl ketone (MIBK) system. Thus, by using a glucose:catalyst weight ratio of 3:1, a glucose conversion of 69% and a HMF yield of 23% were achieved at 175 °C, and after only 90 min of reaction time. The catalytic process is selective toward HMF, which is preserved from ulterior hydration to levulinic acid. Fructose was also detected as by-product of glucose isomerisation with 14% of selectivity. The catalyst is very stable, since no leaching of tantalum species to the liquid phase was found; moreover, the catalytic performance of this acid solid is well recovered after calcination at 550 °C for 2 h.

2014-01-01T00:00:00Z Jiménez Morales, Ignacio Santamaría-González, J. Jiménez-López, A. Maireles-Torres, P. http://hdl.handle.net/10366/163118 2025-04-30T19:50:48Z 2014-01-01T00:00:00Z

[EN]The selective dehydration of glucose to hydroxymethylfurfural (5-HMF) in a biphasic medium (water/methylisobuthylketone) has been studied by using different catalysts based on mesoporous MCM-41 silica containing ZrO2. These catalysts have been: (a) MCM-41 silica doped with Zr in the synthesis step and activated at 550 and 750 °C, (b) this solid impregnated with sulphuric acid and activated at 750 °C, and (c) MCM-41 impregnated with zirconium sulphate and calcined at 750 °C. All these catalysts exhibit acidic properties (282–563 μmol of NH3 desorbed g−1) and high surface areas (359–635 m2 g−1), being active in the dehydration of glucose to HMF at 175 °C and 150 min of reaction time. Catalysts are quite selective, since only fructose and HMF were detected, whereas levulinic acid was absent. The most active catalyst was obtained after incorporation of zirconium into a MCM-41 silica in the synthesis gel (Zr-MCM-550), achieving a HMF yield of 23%. Moreover, the activity of the spent catalyst is fully recovered after calcination at 500 °C during 2 h. TOF values of these catalysts vary between 1.3 and 1.8 mmol of HMF g-1 h-1, being the catalytic performance well correlated with the acidity and textural characteristics of catalysts.

2014-01-01T00:00:00Z Jiménez Morales, Ignacio Teckchandani-Ortiz, A. Santamaría-González, J. Maireles-Torres, P. Jiménez-López, A. http://hdl.handle.net/10366/163117 2025-04-30T19:50:48Z 2014-01-01T00:00:00Z

[EN]Mesoporous tantalum phosphate was prepared from tantalum tartrate and ammonium phosphate monobasic in the presence of an ionic surfactant at room temperature, and subsequent calcined at 550 °C. This solid exhibits a high specific surface area (256 m2 g−1) and strong acidity (1.48 mmol NH3 g−1), and it has been successfully used as solid acid catalyst in the dehydration of glucose to 5-hydroxymethylfurfural (HMF) in a biphasic water/methyl isobutyl ketone medium. By using a glucose:catalyst weight ratio of 3:1, a glucose conversion of 56.3% and a HMF yield of 32.8% were achieved at 170 °C, and after only 1 h of reaction time. The reaction is very selective towards HMF, which is the unique product detected and moreover it is preserved from ulterior hydration to levulinic acid. Fructose was never found as by-product in the reaction. The catalyst is very stable under these experimental conditions, since no leaching of phosphorus or tantalum species to the liquid phase was found. The catalytic performance of this acid solid is well maintained after three catalytic cycles. The high catalytic activity of this mesoporous solid in the dehydration of glucose could be associated to its high acidity and the presence of both Brönsted and Lewis acid sites, which are maintained in water.

2014-01-01T00:00:00Z Jiménez Morales, Ignacio Vila, F. Mariscal, R. Jiménez-López, A. http://hdl.handle.net/10366/163115 2025-04-30T19:50:49Z 2012-01-01T00:00:00Z

[EN]Metallic Ni (10 wt.%) supported on SBA-15 silica and promoted with cerium loading ranged between 2.5 and 10 wt.%, reduced at 723 K during 1 h, were used as catalysts in the hydrogenolysis of a glycerol aqueous solution (80 wt.%) at 473 K and 2.4 MPa of H2 pressure. Whereas pure Ni catalyst mainly produces volatile products by Csingle bondC hydrogenolysis reaction, the promoted cerium catalysts lead to the formation of 1,2-propanediol (1,2-PDO) as majority product. After 8 h of reaction the catalyst with 10 wt.% of Ni and 7.5 wt.% of Ce gives the maximum glycerol conversion and selectivity to 1,2-PDO, with yield of this substance of 24.2%/g of catalyst. The presence of cerium species is essential to produce 1,2-PDO. The effect of cerium oxide is to act as strong acid sites (TPD-NH3), improve the metallic Ni dispersion (XRD, H2 chemisorption and XPS) and to make more difficult their reduction (TPR). The stronger acidity suggests that the formation of acetol takes place easier in these catalysts and subsequently this intermediate is reduced by activated hydrogen from the nearby Ni metallic sites.

2012-01-01T00:00:00Z Jiménez Morales, Ignacio Santamaría-González, J. Maireles-Torres, P. Jiménez López, A. http://hdl.handle.net/10366/163052 2025-04-30T19:50:49Z 2011-01-01T00:00:00Z

[EN]Tantalum penta-ethoxide has been used as precursor for the preparation, after calcination at 575 °C, of a series of catalysts based on tantalum oxy-hydrate supported on SBA-15 silica. The Ta2O5 loading ranges between 5 and 25 wt%, and all of them exhibit acid properties, as determined by NH3-TPD. These catalysts have been assayed in the methanolysis of sunflower oil at 200 °C, being the catalyst with a 15 wt% of Ta2O5 the most active, giving 92.5% of biodiesel yield with solely 6.7% of catalyst with respect to the oil weight. Moreover, no leaching of tantalum was detected in the liquid medium, and these catalysts are able to simultaneously produce the esterification of free fatty acids (FFAs) and the transesterification of triglycerides, even in the presence of 9% of FFAs. The catalytic activity is well maintained in the presence of 5 wt% of water and after three cycles without any treatment.

2011-01-01T00:00:00Z