Articles publicats en revistes (Ciència dels Materials i Química Física)

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Thermodynamic modelling of a thermal energy storage packed bed tank: Exploring the influence of different particle sizes on overall performance
(Elsevier, 2025-05-30) Liu, Xianglei; Luo, Qingyang; Majó, M.; Calderon Diaz, Alejandro; Barreneche, Camila; Li, Jiawei; Tian, Yang; Fernández Renna, Ana Inés
Concentrated solar power combined with thermal energy storage (TES) technology is now widely employed in power generation. To enhance heat transfer efficiency during thermal charging and discharging processes, a packed bed TES system has been developed due to its high heat transfer rate and large heat transfer area. To unveil the overall performance of the packed bed, thermodynamic models are introduced to avoid problems like large size and complex structure. However, current developed models are too vague to study the size effect and pressure drop induced by the particle diameter. In this work, a two-solid-phase model is introduced to evaluate the size effect in packed bed TES systems during charging and discharging, utilizing molten salt and natural volcanic ash as the heat transfer fluid and main solid filler, respectively. Compared to single-phase packed bed, introducing small particles to occupy the void between the large particles yields a low void fraction, and thus the energy storage density is improved by 36.4 %. In the meantime, the thermal charging efficiency is enhanced from 54.37 % to 75.64 %. However, the pressure drop is inevitably increased because of the very low void fraction and the increased surface in contact with the fluid. The pressure drop follows an exponential trend with the changes in particle size. Furthermore, the thermocline in the packed bed requires careful consideration, as it corresponds to the location where the maximum pressure gradient occurs. This work provides insights into the effects of the packed bed induced by the particle size, offering valuable information for the design of next-generation TES packed beds.
Long-Term Compatibility Testing of Solar Salt and Solid Particles at High Temperatures: A Thermal and Chemical Characterization
(John Wiley & Sons, 2025-02-26) Majó, M.; Svobodova Sedlackova, Adela; Barcelona Pons, Pol; Fernández Renna, Ana Inés; Calderon Diaz, Alejandro; Barreneche, Camila
Thermal energy storage offers a viable solution to address the global energy problem of balancing the gap between the energy demand and the energy supply. One of the most advanced and mature thermal energy storage technologies in solar power technologies is a Concentrating Solar Power plant with a tower configuration and molten salts as thermal energy storage. Despite their advantages, molten salts also have limitations that include their corrosive nature, solidification at temperatures below 240°C, and high cost. Therefore, alternative thermal energy storage materials, such as solid-state thermal storage using concrete blocks or ceramic particles, are under research. Solid particles have a high thermal energy storage density, comparable to molten salts, and can withstand higher temperatures, making them well-suited for use in Concentrating Solar Power systems. The use of alternative materials for thermal energy storage is an important aspect of the circular economy concept, which aims to extract the maximum value from resources and reduce greenhouse gas emissions. This work aims to test the compatibility of Solar Salt with several alternative materials for use as thermal energy storage media, including silica sand, commercially sintered bauxite, and two different waste materials from the mining and steel industries. The study compares the thermal and chemical properties of these solid-molten salt mixtures with those of Solar Salt and quantifies the formation of nitrites in Solar Salt as a direct measurement of Solar Salt degradation. Additionally, a rheology study was conducted on the Solar Salt samples, revealing slight changes in viscosity attributed to the nitrite content. Although the thermal properties of the materials remained almost identical and natural and inert ceramic materials exhibited good compatibility, Solar Salt in contact with the waste materials exhibited the formation of nitrites, indicating an expected further degradation of the Solar Salt within these compounds.
Thermal cycling test of solar salt in contact with sustainable solid particles for concentrating solar power (CSP) plants
(MDPI, 2024-05-01) Majó, M.; Svobodova Sedlackova, Adela; Fernández Renna, Ana Inés; Calderon Diaz, Alejandro; Barreneche, Camila
Thermal energy storage (TES) is crucial in bridging the gap between energy demand and supply globally. Concentrated Solar Power (CSP) plants, employing molten salts for thermal storage, stand as an advanced TES technology. However, molten salts have drawbacks like corrosion, solidification at lower temperatures, and high costs. To overcome these limitations, research is focusing on alternative TES materials such as ceramic particles. These solids match molten salts in energy density and can withstand higher temperatures, making them well-suited for CSP systems. This study revolves around subjecting Solar Salt alone and Solar Salt alongside Volcanic Ash (VA) and Electric Arc Furnace Slag (EAFS) to a comprehensive thermal cycling test. This test is designed to assess the compatibility over the thermal cycles of the Solar Salt and the Solar Salt in contact with these solids in a CSP plant with a thermocline configuration. With a final thermal and chemical evaluation, our observations indicate that EAFS and VA demonstrate promising compatibility but an increase in the reduction rate of the Solar Salt due to a catalyst effect from EAFS in contact with the salt. No discernible alterations were detected in the properties of either the solid materials or solar salt when combined.
Mechanical-physical methods for paint removal of recycled bumpers for revalorization in the automotive industry
(Elsevier, 2024-11-05) Zambrano Membrives, Carla; Fernández Renna, Ana Inés; Tamarit, Pablo; Barreneche, Camila
The automotive industry uses plastics in the manufacture of car components due to their benefits such as weight reduction, high friction resistance, energy absorption, and versatility in blending with other materials and in its processability. A wide variety of plastic are used in vehicles. Although up to 13 different types of polymers may be used in a single car model, the most common is Polypropylene (PP). Nowadays, mechanical recycling is the most common method for recycling plastic waste from end-of-life vehicles in the automotive industry. However, challenges arise from material heterogeneity, presence of paint or impurities which affect mechanical properties and quality of recycled materials. Various chemical and physical methods to remove these impurities but economic, technical and feasibility considerations influence the adoption of technology in the industry. The current paper focuses on mechanical-physical procedures for paint removal from recycled automotive thermoplastics, aiming to maintain the properties of the polymer matrix and overcome environmental, economic and complex barriers. The used methods have shown success in removing paint from PP surfaces, with the pressing machine method with the best efficiency at a 38 % reduction. Despite not achieving over 90 % paint removal, these procedures establish fundamental principles for effective industrial mechanical paint depainting.
Evaluation of volcanic ash as a low-cost high-temperature thermal energy storage material for concentrated solar power
(Elsevier, 2024-04-30) Majó, Marc; Svobodova Sedlackova, Adela; Fernández Renna, Ana Inés; Calderon Diaz, Alejandro; Barreneche, Camila
The integration of renewable energy sources is facilitated by TES because it enables the storage and release of excess clean energy, which improves grid stability. In concentrating solar power plants (CSP), solar molten salt is frequently used since it has some advantages such as good thermal properties. However, certain challenges, such as molten salt corrosion, salt solidification, and high production costs, must be carefully considered. An alternative approach gaining attention involves the use of solid ceramic materials capable of withstanding high temperatures as a potential TES medium without the molten salt drawbacks. Elevating the operating temperature of power conversion processes while concurrently reducing capital costs is a strategic means to enhance the competitiveness of these innovative power plants. This study explores the potential of volcanic ash, a low-cost naturally occurring ceramic material, for TES. The evaluation revealed high-temperature stability up to 750 °C, slight mass gain but stable over time, elevated solar absorption, and excellent thermal and chemical stability, even in the presence of molten salts.
The limits of ground-state water splitting on ZnO surfaces: A density functional theory study
(Elsevier B.V., 2024-11-01) Morales Salvador, Raul; Bromley, Stefan Thomas; Viñes Solana, Francesc
The water (H2O) splitting reactions towards hydrogen (H2) and oxygen (O2) production in the ground state are here investigated on ZnO catalyst surfaces by means of density functional theory simulations. To this end, the Zn-terminated and O-terminated (0001) and (000̅) surfaces, respectively, and the non-polar (10̅0) and (11̅0) ones, have been investigated. The reaction thermodynamics has been analysed, being endergonic at normal conditions, and only exergonic at high temperatures and with high partial pressures of reactants. The adsorption of H2O, H2, O2, and reaction intermediates OH, O, and H, underlines the oxophylic character of Zn-terminated (0001) surface, as well as the H-phylic character of O-terminated (000̅) surface, while non-polar surfaces display both O- and H-phylic centers. The adsorption and co-adsorption strengths and elementary steps energy barriers along the reaction path pinpoint the key reaction limiting steps. The H2 formation step has a prohibitive barrier of 4.91 eV on the (000̅) surface, and a more moderate barrier of 2.33 and 1.83 eV for the non-polar (10̅0) and (11̅0) surfaces respectively. On the (0001) surface, the rate limiting step is O2 formation, with an energy barrier of 4.94 eV. Regardless of the surface, a higher affinity towards water would be a way to improve the reaction catalysis. The possible modification of surfaces to reduce the energy costs of the limiting steps are discussed, including the use of light-triggered ZnO catalyst, as well as the simultaneous presence of different surfaces to better split the different reaction steps in an energetically more efficient fashion.
Development of persulfate-based advanced oxidation processes to remove synthetic azo dyes from aqueous matrices
(Elsevier Ltd., 2024-05-01) Brillas, Enric; Oliver Pujol, Ramon
Azo dyes are largely used in many industries and discharged in large volumes of their effluents into the aquatic environment giving rise to non-esthetic pollution and health-risk problems. Due to the high stability of azo dyes in ambient conditions, they cannot be abated in conventional wastewater treatment plants. Over the last fifteen years, the decontamination of dyeing effluents by persulfate (PS)-based advanced oxidation processes (AOPs) has received a great attention. In these methods, PS is activated to be decomposed into sulfate radical anion (SO4•−), which is further partially hydrolyzed to hydroxyl radical (•OH). Superoxide ion (O2•−) and singlet oxygen (1O2) can also be produced as oxidants. This review summarizes the results reported for the discoloration and mineralization of synthetic and real waters contaminated with azo dyes covering up to November 2023. PS activation with iron, non-iron transition metals, and carbonaceous materials catalysts, heat, UVC light, photocatalysis, photodegradation with iron, electrochemical and related processes, microwaves, ozonation, ultrasounds, and other processes is detailed and analyzed. The principles and characteristics of each method are explained with special attention to the operating variables, the different oxidizing species generated yielding radical and non-radical mechanisms, the addition of inorganic anions and natural organic matter, the aqueous matrix, and the by-products identified. Finally, the overall loss of toxicity or partial detoxification of treated azo dye solutions during the PS-based AOPs is discussed.
The recent development of innovative photoelectro-Fenton processes for the effective and cost-effective remediation of organic pollutants in waters
(Elsevier Ltd., 2024-10-08) Brillas, Enric; Peralta-Hernández, Juan Manuel
Wastewaters with toxic and recalcitrant organic contaminants are poorly remediated in conventional wastewater treatment plants. So, powerful processes need to be developed to destroy such organic pollutants to preserve the quality of the aquatic environment. This critical and comprehensive review presents the recent innovative development of photoelectro-Fenton (PEF) covering the period 2019–September 2024. This emerging photo-assisted Fenton-based electrochemical advanced oxidation process (EAOP) is an efficient and cost-effective treatment for water remediation. It possesses a great oxidation power because the in-situ generated hydroxyl radical as oxidant is combined with the photolysis of the organic by-products under UV or sunlight irradiation. The review is initiated by a brief description of the characteristics of the PEF process to stand out in the role of generated oxidizing agents. Further, the homogeneous PEF. PEF-like, solar PEF (SPEF), and SPEF-like processes with iron catalysts are discussed, taking examples of their application to the removal and mineralization of solutions of industrial chemicals, herbicides, dyes, pharmaceuticals, and direct real wastewaters. Novel heterogeneous PEF treatments of such pollutants with solid iron catalysts or functionalized cathodes are analyzed. Finally, novel hybrid processes including PEF/photocatalysis and PEF/photoelectrocatalysis, followed by novel and potent sequential processes like electrocoagulation-PEF and persulfate-PEF, are discussed. Throughout the manuscript, special attention was made to the total operating cost of PEF, which is more expensive than conventional electro-Fenton due to the high electric cost of the UV lamp, pointing to consider the much more cost-effective SPEF as a preferable alternative in practice.
Eliminació d'antibiòtics de matrius aquoses sintètiques i reals mitjançant processos d'oxidació avançada basats en peroximonosulfat. Una revisió dels desenvolupaments recents
(Elsevier Ltd., 2024-01-12) Brillas, Enric; Peralta-Hernández, J.M.
The widespread use of antibiotics for the treatment of bacteriological diseases causes their accumulation at low concentrations in natural waters. This gives health risks to animals and humans since it can increase the damage of the beneficial bacteria, the control of infectious diseases, and the resistance to bacterial infection. Potent oxidation methods are required to remove these pollutants from water because of their inefficient abatement in municipal wastewater treatment plants. Over the last three years in the period 2021–September 2023, powerful peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) have been developed to guaranty the effective removal of antibiotics in synthetic and real waters and wastewater. This review presents a comprehensive analysis of the different procedures proposed to activate PMS-producing strong oxidizing agents like sulfate radical (SO4•−), hydroxyl radical (•OH, radical superoxide ion (O2•−), and non-radical singlet oxygen (1O2) at different proportions depending on the experimental conditions. Iron, non-iron transition metals, biochar, and carbonaceous materials catalytic, UVC, photocatalytic, thermal, electrochemical, and other processes for PMS activation are summarized. The fundamentals and characteristics of these procedures are detailed remarking on their oxidation power to remove antibiotics, the influence of operating variables, the production and detection of radical and non-radical oxidizing agents, the effect of added inorganic anions, natural organic matter, and aqueous matrix, and the identification of by-products formed. Finally, the theoretical and experimental analysis of the change of solution toxicity during the PMS-based AOPs are described.
Density Functional Theory (DFT) and Time-Dependent DFT (TDDFT) Studies of Porphyrin Adsorption on Graphene: Insights on the Effect of Substituents and Central Metal on Adsorption Energies
(Wiley, 2024-12-05) Gara, Rayene; Morales García, Ángel; Arfaoui, Youssef; Illas i Riera, Francesc
Combining metalloporphyrins (MPr) and graphene constitutes key composites in the development of photovoltaic devices. Here, we focus on the analysis of the properties of metalloporphyrins/graphene systems by means of the density functional theory (DFT) and its time-dependent (TDDFT) version, focusing on the ground and singlet excited states. Our benchmark analysis concludes that ωB97XD density functional combined with 6-31G(d)/Def2-TZVP basis set is a better-suited method for simulating accurate MPr adsorption on graphene. It is shown that a reduced atomic model where the external organic shell of the structure is removed provides the same resulting optoelectronic properties of the original model, constituting an important speed-up of the calculations when studying porphyrins-derived molecules. We observe that ZnPr provides the highest light harvesting efficiency (LHE) value. In addition, we find out that the adsorption energy increases monotonically with the size of the graphene flake and the highest stability involves the use of graphene comprising above 500 atoms. Besides, CdPr and HgPr keep their properties as photosensitizers when they are bonded to graphene and show promising values in terms of LHE emerging as suitable solar energy harvesters.
Redesigning electrochemical-based Fenton processes: An updated review exploring advances and innovative strategies using phenol degradation as key performance indicator
(Elsevier B.V., 2024-09-01) Brillas, Enric; Garcia Segura, Sergio
The removal of toxic and persistent organic pollutants is one of the major engineering challenges for water treatment. Development of Fenton-based advanced oxidation processes (AOPs) has shown promising results over water remediation control. The present critical review presents a benchmark framework of understanding on the recent advances of such Fenton-based AOPs based on the abatement of phenol as model pollutant, considering articles published in the period 2019–2023. Fundamentals, the effect of operating variables over the degradation and mineralization of phenol waters, and the role of in situ generated oxidizing agents are summarized and analyzed for understanding the competitiveness and niche application of processes such as homogeneous and heterogeneous Fenton, homogeneous photo-Fenton, hybrid heterogeneous photocatalysis/photo-Fenton, homogeneous and heterogeneous electro-Fenton, and photoelectro-Fenton. Especial emphasis is made on strategies designed to overcome the narrow pH limitation to 3.0 of Fenton reaction. A comparative cost analysis of the above homogeneous processes revealed that homogeneous electro-Fenton was the most viable and cost-effective process. The present review shows that phenol can be used as reference to assess the notable impact of recent advances of Fenton-based AOPs.
Design of donor–acceptor type benzotrithiophene-based covalent organic frameworks for visible-light-driven overall water splitting
(Elsevier Ltd., 2025-12-23) Wang, Chao; Ontiveros Cruz, Diego; Sousa Romero, Carmen
Benefitting from the abundant accessible catalytic sites and well-defined porous architectures enhancing mass transport, two-dimensional (2D) covalent organic frameworks (COFs) are emerging as promising photocatalysts for overall water splitting (OWS). However, the performance of many known COFs for this application remains unsatisfactory, primarily due to stringent requirements for precise band alignment, the limitation posed by overpotentials in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), and mutual interference between the two half-reactions. Herein, we propose eight donor–acceptor (D–A) type 2D benzotrithiophene-based COFs (BTT-COFs), constructed from experimentally feasible building blocks via Schiffbase condensation reaction. By incorporating D–A pairs into the frameworks, these BTT-COFs exhibit enhanced intermolecular charge transfer characteristics as anticipated, thereby promoting efficient carrier separation during OWS. Concurrently, the D–A combinations enable precise modulation of the electronic structure, affording band gaps ranging from 2.35 to 2.89 eV with band-edge arrangements appropriately aligned for photocatalytic OWS under neutral conditions (pH = 7). Among them, the BTT-COF1 (incorporating benzotrithiophene and 1,3,5-triaminobenzene), BTT-COF2 (featuring benzotrithiophene and 2,4,6-triamino-1,3-diazine), and BTT-COF3 (consisting of benzotrithiophene and 2,4,6-triamino-1,3,5-triazine) are found to be capable of spontaneously driving OWS under their intrinsic photoinduced bias potentials. The remaining BTTCOFs require external bias to facilitate the reaction. Crucially, the theoretical solar-to-hydrogen (STH) conversion efficiencies of these materials range from 1.8 % to 10.0 %, highlighting their potential as efficient photocatalysts for OWS.
First principles modeling of composites involving TiO2 clusters supported on M2C MXenes
(Royal Society of Chemistry, 2024-12-01) Keyhanian, Masoomeh; García-Romeral, Néstor; Morales García, Ángel; Viñes Solana, Francesc; Illas i Riera, Francesc
First-principles calculations based on density functional theory are performed to investigate the formation of titania/MXene composites taking (TiO2)5/M2C (M = Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W) as cases of study. The present systematic analysis confirms a favorable, high exothermic interaction, which promotes important structural reconstructions of the (TiO2)5 cluster along with charge transfer from the MXene to titania. MXenes composed of d3 transition metals promote the strongest interaction, deformation energy, and charge transfer, followed by d4 and d5 M2C MXenes. We provide evidence that the formation of these (TiO2)5/M2C composites is governed by charge transfer, leading to scaling relationships. By using the electronegativity of the metal composing MXene and the MXene d-band center, we also establish linear correlations that can be used to predict the interaction strength of (TiO2)5/M2C composites just from the knowledge of the MXene composition. It is likely that the present trends hold for other TiO2/MXene composites.
Guest selectivity of [Ni2] supramolecular helicates
(Royal Society of Chemistry, 2024-06-29) Imperato, Manuel; Nicolini, Alessio; Ribas Ariño, Jordi; Antkowiak, Michal; Roubeau, Olivier; Cornia, Andrea; Novikov, Valentin; Barrios Moreno, Leoní Alejandra; Aromí Bedmar, Guillem
Two new paramagnetic supramolecular helicates with the formula (X@[Ni2L3])3+ (X = Cl, or Br; L = a bis-pyrazolylpyridine ligand) have been prepared and are described. Helicates of this metal are very rare with virtually no prior examples of them acting as hosts of anionic species. The persistence of the new assemblies in solution has been demonstrated unambiguously by mass spectrometry and paramagnetic 1H NMR. This has allowed us to establish the preference of the coordination [Ni2] host for Cl− over Br−, in agreement with DFT calculations. These results show the promise of the use of metallohelicates as suitable systems for the selective encapsulation of specific anions in solution.
Copper- and manganese-based layered hybrid organic–inorganic compounds with polymorphic transitions as energy storage materials
(Royal Society of Chemistry, 2024-06-28) Salgado Pizarro, Rebeca; Puigjaner Vallet, Ma. Cristina; García-Arch, Josué; Fernández Renna, Ana Inés; Barreneche, Camila
Solid–solid phase change materials (ss-PCM) have emerged as a promising alternative to traditional methods of thermal regulation, such as solid–liquid transformations. Due to their wide operational temperature range and competitive performance, ss-PCM materials are increasingly being explored for their potential in cooling electronic devices. Here, we explore the potential of layered hybrid organic–inorganic perovskites (LHOIPs) as thermal energy storage materials for passive cooling applications. Two formulations, bis(dodecylammonium) tetrachlorocuprate(II) (CuC12) and bis(dodecylammonium) tetrachloromanganate(II) (MnC12) were synthesised and comprehensively characterised. The analyses revealed that these materials present a two-dimensional structure with a triclinic conformation at 100 K. Notably, both materials exhibited a polymorphic transformation with low thermal hysteresis (1.3–2.5 K). These findings indicate that these materials hold significant potential as thermoregulator materials in cooling electronics. Furthermore, both CuC12 and MnC12 demonstrated good thermal stability compared to other types of ss-PCM. Overall, the findings of this study suggest that LHOIPs, particularly CuC12 and MnC12, are promising candidates for further exploration as thermal energy storage materials in electronic cooling applications.
Rational design of organic diradicals with robust high-spin ground state based on antiaromatic linkers
(Royal Society of Chemistry, 2024-11-21) Santiago, Raul; Carvajal Barba, M. Àngels; Poater i Teixidor, Jordi; Moreira, Ibério de Pinho Ribeiro; Bromley, Stefan Thomas; Deumal i Solé, Mercè; Ribas Ariño, Jordi
Fully-organic molecules with high-spin ground states are promising building blocks for new lightweight flexible magnetic materials for emerging technological applications (e.g. spintronics). In this study, we explore the potential of diradicals made of two diphenylmethyl-based open-shell cores covalently linked via different types of pentalene and diazapentalene-based antiaromatic couplers (including dibenzopentalenes and acene-inserted derivatives). Accurate electronic structure calculations have been employed to target non-bonding and non-disjoint frontier molecular orbitals that favor high-spin configurations, leading to the identification of diradicals displaying robust triplet ground states. These candidates exhibit singlet-triplet energy gaps that are up to ten times the thermal energy at room temperature. These substantial gaps emerge from strong interactions between the p-systems of the open-shell centers and the antiaromatic coupler. These interactions not only result in high spin states but are also found to lead to an enhanced stability of the diradicals by drastically dampening their inherent antiaromatic character as compared to the bare couplers, and promoting a high degree of spin density delocalization. These findings highlight the potential of pentalene-based diradicals as building blocks for developing new advanced fully organic magnetic materials.
Gas-Phase Production of Hydroxylated Silicon Oxide Cluster Cations: Structure, Infrared Spectroscopy, and Astronomical Relevance
(American Chemical Society, 2024-06-20) Donato, Andreu A. de; Ghejan, Bianca-Andreea; Bakker, Joost M; Bernhardt, Thorsten M.; Bromley, Stefan Thomas; Lang, Sandra M.
The interaction of free cationic silicon oxide clusters, SixOy+ (x = 2–5, y ≥ x), with dilute water vapor, was investigated in a flow tube reactor. Product mass distributions indicate cluster size-dependent dissociative water adsorption. To probe the structure and vibrational spectra of the resulting SixOyH2+ (x = 2–4) clusters, we employed infrared multiple photon dissociation spectroscopy and density functional theory calculations. The planar rhombic cluster core of the disilicon oxides (x = 2) appears to be retained upon dissociative adsorption of one H2O unit, whereas a significant structural transformation of the tri- and tetra-silicon oxides (x = 3 and 4) is induced, resulting in an increased coordination of the Si atoms and more 3D cluster structures. In an astronomical context, we discuss the potential relevance of SixOyHz+ clusters as seeds for dust nucleation and catalysts for carbon-based chemistry in diffuse or translucent interstellar clouds, where all the necessary conditions for producing these species are found. In the produced clusters, the frequency of the isolated silanol Si–OH stretching vibrational mode is considerably blue-shifted compared to that in hydroxylated bulk silica and small inorganic compounds. This mode has a characteristic frequency range between 1200 cm–1 (8.3 μm) and 1090 cm–1 (9.2 μm) and is associated with the anomalously small Si–OH bond lengths in these ionised species. In infrared observations such high frequency Si–O stretching modes are usually associated with a pure bulk silica component of silicate cosmic dust. The presence of SixOyH2+ clusters in low silica astrophysical environments could thus potentially be detected via their signature Si−O band using the James Webb space telescope.
Coupling wastewater treatment with fuel cells and hydrogen technology
(Elsevier B.V., 2024-04-25) Alcaide Fernández de Vega, Fernando; Sirés Sadornil, Ignacio; Brillas, Enric; Cabot Julià, Pere-Lluís
Fuel cells (FCs) and hydrogen technologies are emerging renewable energy sources with promising results when applied to wastewater treatment (WWT). These devices serve not only for power generation, but some specific FCs can also be employed for degradation of pollutants and synthesis of intermediates needed in WWT. Microbial FCs are potent devices for WWT, even containing refractory pollutants. Despite being a nascent technology with high capital expenses, the use of cost-effective materials, reduction of operational cost, and increased generation of energy and value-added chemicals such as hydrogen will facilitate the market penetration through selected niches and hybridization with alternative WWT technologies.
Stable 1,3,2-Benzodithiazolyl Radicals: Modification ofReactivity, Crystal Packing, and Solid State MagneticProperties by Fluorination
(Wiley-VCH Verlag, 2026-02-26) Buravlev, Alexander A.; Makarov, Alexander Yu.; Ribas Ariño, Jordi; Carvajal Barba, M. Àngels; Deumal i Solé, Mercè; Balmohammadi, Yaser; Grabowsky, Simon; Shundrina, Inna K.; Zakharov, Boris A.; Irtegova, Irina G.; Uvarov, Mikhail N.; Bogomyakov, Artem S; Bagryanskaya, Irina Yu.; Shundrin, Leonid A.; Zibarev, Andrey V.
Impact of fluorination on crystal and molecular structure, heteroatom reactivity, and solid-state magnetic properties of thermally-stable π-radicals is studied experimentally and computationally with 1,3,2-benzodithiazolyl 1· and its 4,7-difluoro, 4,5,6,7-tetra-fluoro, and 4,7-difluoro-5,6-(hexafluoropropane-1,3-diyl) derivatives 2-4, respectively. Radicals 2 -4 are isolated by vacuum thermolysis of their unusual covalent 2:1 adducts with 7,7,8,8-tetracyanoquinodimethane. The impact of fluorination on reactivity is evidenced by transformation of 2-4 and 2 +-4 + into corresponding 2H-1-oxo-1,3,2-benzodithiazoles under the influence of air’s or solvents’ moisture; back transformation into the cations under the action of protic acids; and formation of a paramagnetic molecular complex between 3 and naphthalene, whereas 1 and octafluoronaphthalene do not exhibit complexation. The crystal structures of 3 and 4 reveal a novel packing motif featuring radical pairs linked by four-center interactions that stack into offset π-columns, forming a unique zip-π-stack synthon that incorporates head-over-tail π-pairs of radicals. Despite the formation of π-pairs, polycrystalline 3 and 4 display a nonzero effective magnetic moment that rises with temperature above 200 K, although the values remain significantly lower than those of the high-temperature polymorphs of magnetically-bistable 1 and 2·. This behavior can be rationalized by different magnetic topologies and values of spin exchange between the radicals.
Engineered SnO 2/BiOI fibers via electrospinning for robust visible-light/peroxymonosulfate -driven multipollutant mineralization
(Elsevier B.V., 2026-03-01) Huidobro, Laura; Allés, Miquel; Abid, Mahmoud; Bechelany, Mikhael; Sousa Romero, Carmen; Gómez, Elvira; Serrà i Ramos, Albert
Engineered photocatalysts capable of operating under visible light and realistic water matrices are needed to address emerging pharmaceutical contaminants. Here, we fabricate SnO2/BiOI fibrous heterostructures by electrospinning SnO2 nanofibers decorated with solvothermally synthesized BiOI followed by calcination. The electrospun fibers provide a mechanically robust, high-surface-area scaffold, while BiOI incorporation enhances visible-light absorption and creates SnO2/BiOI heterointerfaces. Textural, optical, and spectroscopic analyses reveal progressive surface decoration, increased surface area, and defect-rich Bi environments as BiOI loading increases. Using tetracycline (TC) as a model contaminant at neutral pH, SnO2/BiOI composites markedly outperform pristine SnO2 under visible light and/or peroxymonosulfate (PMS), with an optimal BiOI content (SBO2) under single-stimulus conditions and near-complete TC mineralization for the highest loading (SBO3) in the PMS + visible-light system. Radical scavenging indicates that SO4•− and •OH are the dominant reactive species, with O2•−, h+ and e− playing secondary roles. A multipollutant mixture (TC, sulfamethoxazole, levofloxacin, lansoprazole) is mineralized by >80% in both Milli-Q and tap water, and SBO3 retains high activity over nine cycles with Bi and I leaching below 0.05% after 48 h. Density functional theory calculations, combined with XPS, support an S-scheme SnO2/BiOI heterojunction, enabling spatial separation of strongly reducing electrons in BiOI and oxidizing holes in SnO2. Although high PMS loadings can partially mask intrinsic catalyst differences, these results outline a practical design platform for heterogeneous (slurry), visible-responsive, PMS-assisted photocatalysts for pharmaceutical-laden effluents.

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