Open Access
Functionalization of 3D printed ABS filters with MOF for toxic gas removal
(Elsevier, 2020) Pellejero, Ismael; Almazán, Fernando; Lafuente, María; Urbiztondo, Miguel A.; Dobrek, Martin; Bechelany, Mikhael; Julbe, Anne; Gandía Pascual, Luis; Institute for Advanced Materials and Mathematics - INAMAT2; Gobierno de Navarra / Nafarroako Gobernua, PC052-23; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Acrylonitrile butadiene styrene (ABS) is one of the most extensively used polymer in 3D printing manufacturing due to its competitive thermal and mechanical properties. Recently, a special attention has been devoted to novel ABS composites featuring extra functionalities e.g. in the area of VOC removal. Herein, we report on a facile protocol for the functionalization of 3D printed ABS filters with a MOF (Metal- Organic Framework) material (ZIF-8) targeting the conception of attractive gas filters. The proposed synthesis strategy consists in low temperature ALD (Atomic Layer Deposition) of ZnO on the ABS grid followed by the hydrothermal conversion of ZnO to ZIF-8, both steps being conducted at 60 °C. In such way, the method enables an effective growth of ZIF-8 without altering the stability of the polymeric ABS support. The as-fabricated ABS/ZIF-8 filters offer a promising adsorption behaviour for dimethyl methylphosphonate (~20.4 mg of DMMP per gram of ZIF-8), thus proving their potential for toxic gas capture applications.
Open Access
High power illumination system for uniform, isotropic and real time controlled irradiance in photoactivated processes research
(Elsevier, 2024) Sáenz Gamasa, Carlos; Hernández Salueña, Begoña; Sanz Carrillo, Diego; Pellejero, Ismael; Gandía Pascual, Luis; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
In the study of photocatalytic and photoactivated processes and devices a tight control on the illumination conditions is mandatory. The practical challenges in the determination of the necessary photonic quantities pose serious difficulties in the characterization of catalytic performance and reactor designs and configurations, compromising an effective comparison between different experiments. To overcome these limitations, we have designed and constructed a new illumination system based in the concept of the integrating sphere (IS). The system provides uniform and isotropic illumination on the sample, either in batch or continuous flow modes, being these characteristics independent of the sample geometry. It allows direct, non-contact and real time determination of the photonic quantities as well as versatile control on the irradiance values and its spectral characteristics. It can be also scaled up to admit samples of different sizes without affecting its operational behaviour. The performance of the IS system has been determined in comparison with a second illumination system, mounted on an optical bench, that provides quasi-parallel beam (QPB) nearly uniform illumination in tightly controlled conditions. System performance is studied using three sample geometries: a standard quartz cuvette, a thin straight tube and a microreactor by means of potassium ferrioxalate actinometry. Results indicate that the illumination geometry and the angular distribution of the incoming light greatly affect the absorption at the sample. The sample light absorption efficiency can be obtained with statistical uncertainties of about 3% and in very good agreement with theoretical estimations.
Open Access
In situ synthesis of SERS-active Au@POM nanostructures in a microfluidic device for real-time detection of water pollutants
(American Chemical Society, 2020) Lafuente Adiego, Marta; Pellejero, Ismael; Clemente, Alberto; Urbiztondo, Miguel A.; Mallada, Reyes; Reinoso, Santiago; Pina, María del Pilar; Gandía Pascual, Luis; Institute for Advanced Materials and Mathematics - INAMAT2; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We present a simple, versatile and low-cost approach for the preparation of SERS-active regions within a microfluidic channel 50 cm in length. The approach involves the UV-light-driven formation of polyoxometalate-decorated gold nanostructures, Au@POM (POM: H3PW12O40 (PW) and H3PMo12O40 (PMo)), that self-assemble in situ on the surface of the PDMS microchannels without any extra functionalization procedure. The fabricated LoCs were characterized by SEM, UV-Vis, Raman, XRD and XPS techniques. The SERS activity of the resulting Au@POM–coated lab-on-a-chip (LoC) devices was evaluated in both static and flow conditions using Rhodamine R6G. The SERS response of Au@PW–based LoCs was found superior to Au@PMo counterparts and outstanding when compared to reported data on metal@POM nanocomposites. We demonstrate the potentialities of both Au@POM–coated LoCs as analytical platforms for real time detection of the organophosphorous pesticide Paraoxon-methyl at 10-6 M concentration level.
Open Access
Assessing thermal and nonthermal contributions during CO2 hydrogenation over ruthenium catalysts: effects of the illumination conditions and the nature of the support
(Elsevier, 2024-12-05) Imizcoz Aramburu, Mikel; Pellejero, Ismael; Gandía Pascual, Luis; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
Photothermal catalysis offers a promising approach for the clean production of carbon-neutral chemicals from CO2 through reactions with hydrogen as a renewable energy carrier. While the combined action of photons and heat from solar radiation can drive catalytic reactions, the interactions involved are very complex, depend on the catalyst composition, and often remain uncertain. Herein, we assessed the thermal and nonthermal contributions to the overall activities of a series of Ru catalysts during the photothermal hydrogenation of CO2. TiO2 (anatase/rutile mixture), anatase, ZrO2, CeO2, and SiO2 were used as supports for Ru nanoparticles (2 wt%) that were deposited using an amino-acid-assisted method. Ru@TiO2 and Ru@ZrO2 presented the best catalytic performance at relatively low reaction temperatures (220-250 °C), whereas Ru@CeO2 was the most active catalyst above 300 °C. The catalysts were tested under direct and indirect illumination conditions to assess their thermal and nonthermal contributions to the overall production of methane, with a nonthermal contribution of 60-75 % observed at the highest applied irradiance (2.2 W·cm-²). Ru@ZrO2 registered the highest nonthermal CH4 production, which is tentatively ascribable to the participation of photo-generated electrons in the catalytic reaction and the light-induced formation of oxygen vacancies. The selected catalysts were also tested under concentrated-sunlight conditions in outdoor experiments, with a maximum methane production of 200 mmolCH4·gcat-¹·h-¹ achieved over Ru@ZrO2, which resulted in 31 % CO2 conversion and 92 % selectivity for methane in a continuous flow reactor at a space velocity of 1500 mLSTP·g-¹·min-¹.
Open Access
The 3D-printing fabrication of multichannel silicone microreactors for catalytic applications
(MDPI, 2023) Ibáñez de Garayo Quilchano, Alejandro; Imizcoz Aramburu, Mikel; Maisterra Udi, Maitane; Almazán, Fernando; Sanz Carrillo, Diego; Bimbela Serrano, Fernando; Cornejo Ibergallartu, Alfonso; Pellejero, Ismael; Gandía Pascual, Luis; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Microstructured reactors (MSRs) are especially indicated for highly demanding heterogeneous catalysis due to the small channel dimensions that minimize diffusional limitations and enhance mass and heat transport between the fluid and the catalyst. Herein, we present the fabrication protocol of the fused filament 3D printing of silicone monolithic microreactors based on a multichannel design. Microchannels of 200 to 800 µm in width and up to 20 mm in length were developed following the scaffold-removal procedure using acrylonitrile butadiene styrene (ABS) as the material for the 3D-printed scaffold fabrication, polydimethylsiloxane (PDMS) as the building material, and acetone as the ABS removing agent. The main printing parameters such as temperature and printing velocity were optimized in order to minimize the bridging effect and filament collapsing and intercrossing. Heterogeneous catalysts were incorporated into the microchannel walls during fabrication, thus avoiding further post-processing steps. The nanoparticulated catalyst was deposited on ABS scaffolds through dip coating and transferred to the microchannel walls during the PDMS pouring step and subsequent scaffold removal. Two different designs of the silicone monolithic microreactors were tested for four catalytic applications, namely liquid-phase 2-nitrophenol photohydrogenation and methylene blue photodegradation in aqueous media, lignin depolymerization in ethanol, and gas-phase CO2 hydrogenation, in order to investigate the microreactor performance under different reaction conditions (temperature and solvent) and establish the possible range of applications.
Open Access
Innovative catalyst integration on transparent silicone microreactors for photocatalytic applications
(Elsevier, 2022) Pellejero, Ismael; Clemente, Alberto; Navajas León, Alberto; Vesperinas Oroz, José Javier; Urbiztondo, Miguel A.; Gandía Pascual, Luis; Institute for Advanced Materials and Mathematics - INAMAT2; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Reproducible and controllable incorporation and immobilization of catalysts and other active particles onto silicone microreactor channels is still challenging. In this work, we present an innovative fabrication protocol to attain affordable, custom-designed photocatalytic microreactors in a fast and simple manner. In this protocol, a 3D-printed ABS microreactor mold is first dip-coated with the photocatalyst, and subsequently, the catalytic layer is transferred onto the microchannel walls by indirect immobilization during the silicone casting and scaffold removal step. Serpentine-shaped microreactors have been satisfactorily fabricated with Au@POM-impregnated TiO2 nanoparticles (Au@POM/TiO2; Au 0.18 % w/w, POM: H3PW12O40) as the integrated photocatalytic layer. The suitability of our fabrication method has been validated on the basis of the excellent photocatalytic performance shown by the microreactors in a model test reaction such as the continuous-flow photoreduction of 4-nitrophenol to 4-aminophenol with NaBH4 and monitored by UV-Vis spectroscopy.
Open Access
Three-dimensional printing of acrylonitrile butadiene styrene microreactors for photocatalytic applications
(American Chemical Society, 2020) Cabrera Barrios, Aarón; Pellejero, Ismael; Oroz Mateo, Tamara; Salazar, Cristina; Navajas León, Alberto; Fernandez Acevedo, Claudio; Gandía Pascual, Luis; Institute for Advanced Materials and Mathematics - INAMAT2; Gobierno de Navarra / Nafarroako Gobernua, PC003-004; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Miniaturization is a key aspect for many technological applications and the use of microreactors is an excellent solution for the intensification of chemical processes for a variety of applications. However, standard microfabrication requires large facilities and intricate fabrication protocols, and consequently it is not easily available, generally resulting in high production costs. Herein, we present a very cheap, fast and easy microreactor design for photocatalytic applications based on direct fused filament 3D printing as a facilitating and widespread technology. The microreactor consists of three bodies directly printed in ABS (Acrylonitrile Butadiene Styrene): a main body with a serpentine microchannel pattern where the photocatalyst is placed, a top holder with a transparent polymer window, and a base to clamp the parts. Several microreactor units were coated with TiO2 doped with Cu (2.4 wt.%) nanoparticles synthesized by FSP (Flame Spray Pyrolysis) and tested for the photocatalytic degradation of two water pollutants showing excellent performance.
Open Access
UiO-66 MOF-Derived Ru@ZrO2 catalysts for photo-thermal CO2 hydrogenation
(MDPI, 2023) Almazán, Fernando; Lafuente Adiego, Marta; Echarte Villeras, Amaya; Imizcoz Aramburu, Mikel; Pellejero, Ismael; Gandía Pascual, Luis; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The use of metal–organic frameworks (MOFs) as templates or precursors in the manufacture of heterogeneous catalysts is highly attractive due to the transfer of MOFs’ inherent porosity and homogeneous metallic distribution to the derived structure. Herein, we report on the preparation of MOF-derived Ru@ZrO2 catalysts by controlled thermal treatment of zirconium-based MOF UiO66 with ruthenium moieties. Ru3+ (3 or 10 mol%) precursor was added to UiO-66 synthesis and, subsequently, the as-synthesized hybrid structure was calcined in flowing air at different temperatures (400–600 ◦C) to obtain ZrO2 -derived oxides doped with highly dispersed Ru metallic clusters. The materials were tested for the catalytic photo-thermal conversion of CO2 to CH4 . Methanation experiments were conducted in a continuous flow (feed flow rate of 5 sccm and 1:4 CO2 to H2 molar ratio) reactor at temperatures from 80 to 300 ◦C. Ru0.10@ZrO2 catalyst calcined at 600 ◦C was able to hydrogenate CO2 to CH4 with production rates up to 65 mmolCH4·gcat. –1 ·h –1, CH4 yield of 80% and nearly 100% selectivity at 300 ◦C. The effect of the illumination was investigated with this catalyst using a high-power visible LED. A CO2 conversion enhancement from 18% to 38% was measured when 24 sun of visible LED radiation was applied, mainly due to the increase in the temperature as a result of the efficient absorption of the radiation received. MOF-derived Ru@ZrO2 catalysts have resulted to be noticeably active materials for the photo-thermal hydrogenation of CO2 for the purpose of the production of carbon-neutral methane. A remarkable effect of the ZrO2 crystalline phase on the CH4 selectivity has been found, with monoclinic zirconia being much more selective to CH4 than its cubic allotrope.
Open Access
Gold nanoparticles capped with a novel titanium(iv)-containing polyoxomolybdate cluster: selective and enhanced bactericidal effect against Escherichia coli
(Wiley, 2024) Paesa, Mónica; Almazán, Fernando; Yus Argón, Cristina; Sebastián, Víctor; Arruebo Gordo, Manuel; Reinoso, Santiago; Pellejero, Ismael; Gandía Pascual, Luis; Mendoza, Gracia; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Bacterial infections are a public health threat of increasing concern in medical care systems; hence, the search for novel strategies to lower the use of antibiotics and their harmful effects becomes imperative. Herein, the antimicrobial performance of four polyoxometalate (POM)-stabilized gold nanoparticles (Au@POM) against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as Gram-negative and Gram-positive bacteria models, respectively, is studied. The bactericidal studies performed, both in planktonic and sessile forms, evidence the antimicrobial potential of these hybrid nanostructures with selectivity toward Gram-negative species. In particular, the Au@GeMoTi composite with the novel [Ti2(HGeMo7O28)2]10¿ POM capping ligand exhibits outstanding bactericidal efficiency with a minimum inhibitory concentration of just 3.12 µm for the E. coli strain, thus outperforming the other three Au@POM counterparts. GeMoTi represents the fourth example of a water-soluble TiIV-containing polyoxomolybdate, and among them, the first sandwich-type structure having heteroatoms in high-oxidation state. The evaluation of the bactericidal mechanisms of action points to the cell membrane hyperpolarization, disruption, and subsequent nucleotide leakage and the low cytotoxicity exerted on five different cell lines at antimicrobial doses demonstrates the antibiotic-like character. These studies highlight the successful design and development of a new POM-based nanomaterial able to eradicate Gram-negative bacteria without damaging mammalian cells.