Scientific Papers in SCI

This work presents the surface modification of commercially pure Ti specimens (c.p.-Ti) prepared by conventional powder metallurgy by depositing a thin film of a ß-Ti alloy (Ti-35Nb-7Zr-5Ta, wt. %, TNZT). Two types of pulsed technologies: conventional (p-DC) and high-power impulse magnetron sputtering (HiPIMS), with and without bias assistance (−60 V) under similar power conditions (250 W) were applied on titanium specimens and silicon substrates leading to different film morphologies and functional properties. Microstructural, X-ray diffraction, nanoindentation, surface wetting, XPS and electrochemical impedance measurements were done to characterize their functionality. All the coatings presented a reduced Young's Modulus (E ≤ 80GPa) compared to the bulk Ti, representing a reduction of more than 30 %. This decrease can significantly contribute to the reduction of the stress-shielding effect, mitigating the risk of implant loosening and failure. The hardness values of TNZT coatings, slightly lower than c.p.-Ti substrate, range from 4.1 to 4.7 GPa. XPS analysis shows a passivation layer of TiO₂, Nb₂O₅, and ZrO₂, which offers high impedance and excellent corrosion resistance. The best compromise between mechanical and corrosion properties is achieved with the HiPIMS technology, thanks to its compact film microstructure with high electrical resistance, despite its limited thickness of about 1 μm. 

In contemporary catalytic interface exploration, experimental studies often take a backseat to theoretical simulations, hindering the development of pristine catalytic interfaces. This research leverages monolayer dispersion theory to design an efficient CO oxidation catalyst through precise manipulation of non-precious metal NiO-CeO2 interfaces. Employing the pioneering XRD extrapolation method, we fabricated monolayer dispersed Ni-O-Ce and Ce-O-Ni interfaces, unlocking insights into their impact on the CO oxidation mechanism. The method accurately quantified monolayer dispersion capacities: 0.526 mmol NiO/(100 m2 CeO2) for NiO/CeO2 and 0.0638 mmol CeO2/(100 m2 NiO) for CeO2/NiO, revealing intricate interactions between active components and supports. Utilizing numerical values derived from monolayer dispersion theory, we constructed CeO2-sup- ported NiO (Ni-O-Ce) and NiO-supported CeO2 (Ce-O-Ni) catalysts in a monolayer dispersed state. The Ni-O-Ce interface, generating abundant oxygen vacancies, significantly enhanced CO adsorption and facilitated surface reactive oxygen species production, leading to a remarkable 14-fold increase in intrinsic CO oxidation activity and a notable 4.2-fold improvement in water resistance. Integrating XRD extrapolation, H2-TPR, O2-TPD, COTPD, XPS, Raman, and in situ IR techniques, our study demonstrates the feasibility of crafting efficient catalysts with monolayer dispersed atomic-scale catalytic interfaces to elucidate the mechanisms underlying catalytic interface effects on CO oxidation.

Escalating SOx and NOx emissions from industrial plants necessitates customized scrubbing solutions to improve removal efficiency and tackle cost limitations in existing wet FGD units. This work investigates the real-time intensified removal pathways via an innovative two-stage countercurrent spray tower configuration strategically integrating NaOH (Ma) and NaOH/NaClO (Ma/Mb) to remove SOx and NOx emissions simultaneously from the industrial stack through a comprehensive parametric study of absorbents concentration, reaction temperature, gas flow rate, liquid to gas ratio (FL/FG), and absorbent showering head. Flue gas stream comprising SO2 bearing 4500 ppm, SO3 bearing 300 ppm, 70 ppm NO, and 50 ppm NO2 brought into contact with two scrubbing solutions as Ma, and a complex absorbent of Ma/Mb at varying respective ratios. Ninety-two percent SOx emissions were removed using 5% NaOH with double-stage scrubbing, while NOx removal was observed below 50%. Adding NaClO facilitates additional "free radical (ClO-)" chemical pathways for gases to react and decompose into ionic forms for easier solubilization so as to significantly enhance the removal capacities for both SOx and NOx compounds. NaClO oxidizer, along with NaOH, boosted the respective removal efficiencies of SOx to 99.6% and 92% NOx, proving complementary media integration advantages arising from staged exposure and bubbly interphase mass transfer phenomena. The customized synergistic effect of Ma and Mb promoted the development of an additional free radical oxidation route while sustaining the solubilization of SOx/NOx in caustic, driving toward fractional detoxification. A dimensionless emission performance model was developed along with mechanism validation through DFT in context to the successful formation of residual salts by applying the DMol3 tool in Materials Studio by exploring the convergence analysis, geometry optimization, and COSMO sigma profile.

Poly(vinylidene fluoride) (PVDF) is a piezoelectric and thermoplastic material with great potential for additive manufacturing (AM) applications. Using barium titanate (BaTiO₃) as filler, PVDF-based composite materials were developed, characterized, and processed by AM material extrusion (MEX). The morphological features and phase transformations occurring throughout the processing of BaTiO₃-filled PVDF, from the compounding to the printed part, were analyzed. The morphology of the powder feedstock after dispersion in a high-energy ball mill changed from spheroidal to laminar and β-phase formation was favored. Microhardness gradually increased with the BaTiO₃ content, obtaining an enhancement of ~60% for a content of 25 vol%, and supported the good dispersion of the filler. A ~48% increase of the dielectric permittivity was also achieved. After extrusion, filaments with a filler content of 15 vol% showed a more stable diameter, as well as higher crystallinity and surface roughness, compared with those with lower BaTiO₃ contents. Material extrusion of filament and direct printing of pellets based on MEX were successfully used to obtain AM parts. Composite parts showed enhanced surface roughness, hydrophilicity, and flexural modulus (up to ~33% for the 7 vol% composite compared with the PVDF), thus leading to superior mechanical characteristics and potential biomedical applications.

Dredged material is a common environmental and economic issue worldwide. Tons of highly contaminated material, derived from cleaning the bottoms of bays and harbours, are stored until depuration. These volumes occupy huge extensions and require costly treatments. The Ria of Huelva (southwest Spain) receives additionally high metal contamination inputs from the Odiel and Tinto Rivers which are strongly affected by acid mine drainage (acid lixiviates with high metal content and sulphates). These two circumstances convert the port of Huelva into an acceptor/accumulator of contamination. The current study proposes an alternative active treatment of dredged material and mining residues using ASEC (Adiabatic Sonic Evaporation and Crystallization) technology to obtain distilled water and valuable solid conglomerates. Different samples were depurated and the efficiency of the technology was tested. The results show a complete recovery of the treated volumes with high-quality water (pH similar to 7, EC < 56 mu S/cm, complete removal of dissolved elements). Also, the characterization of the dried solids enable the calculation of approximate revenues from the valorization of some potentially exploitable elements (Rio Tinto: 4 M, Tharsis: 3.7 M, dredged material: 2.5 M USD/yr). The avoidance of residue discharge plus the aggregated value would promote a circular economy in sectors such as mining and dredging activities.

This article discusses the 'power-to-X' (P2X) concept, highlighting the integral role of non-thermal plasma (NTP) in P2X for the eco-friendly production of chemicals and valuable fuels. NTP with unique thermally non-equilibrium characteristics, enables exotic reactions to occur under ambient conditions. This review summarizes the plasma-based P2X systems, including plasma discharges, reactor configurations, catalytic or non-catalytic processes, and modeling techniques. Especially, the potential of NTP to directly convert stable molecules including CO2, CH4 and air/N2 is critically examined. Additionally, we further present and discuss hybrid technologies that integrate NTP with photocatalysis, electrocatalysis, and biocatalysis, broadening its applications in P2X. It concludes by identifying key challenges, such as high energy consumption, and calls for the outlook in plasma catalysis and complex reaction systems to generate valuable products efficiently and sustainably, and achieve the industrial viability of the proposed plasma P2X strategy.

The development of highly efficient and selective catalysts for carbonylation reactions represents a significant challenge in catalysis. Single-atom catalysts (SACs) have postulated as promising candidates able to combine the strengths of both homogeneous and heterogeneous catalysts. In this paper, we review recent advances in tailoring solid supports for SACs to enhance their catalytic performance in carbonylation reactions. We first discuss the effect of supports on the hydroformylation reaction catalysed by SACs, followed by recent advances for methanol, ethanol, and dimethyl ether carbonylation reactions, focusing on the design of halide-free catalysts with improved activity and stability. Finally, oxidative carbonylation is discussed. Overall, this review highlights the importance of tailoring solid supports for SACs to achieve highly active and selective catalysts in carbonylation reactions, paving the way for future developments in sustainable catalysis.

La2Mo2O9 is acknowledged as an exceptional oxide ion conductor. It undergoes a reversible phase transition around 580 degrees C from the nonconductive low-temperature monoclinic alpha-La2Mo2O9 phase to the highly conductive high-temperature cubic beta-La2Mo2O9 phase. In addition, La2Mo2O9 demonstrates complex chemistry under reducing conditions. This study reports, for the first time, the stabilization at ambient temperature of a novel cubic phase through a topotactic reduction of alpha-La2Mo2O9 employing CaH2. This phase contains approximately similar to 3 atom % oxygen vacancies relative to the nominal composition (La2Mo2O8.68(1)). The cubic symmetry is associated with a static distribution of these vacancies, in contrast to the dynamic distribution observed in the high-temperature cubic beta-La2Mo2O9 phase reported previously. Additionally, the material exhibits mixed-ion-electronic conduction, which expands its potential use in applications requiring both ionic and electronic transport.

Active and sustainable food packaging materials were prepared through solvent casting, by blending tea waste (TW) extract rich in bioactive molecules with a neat polylactide (PLA) polymeric matrix. The optimization of tea waste extraction using a response surface methodology allowed achieving efficient yield and high phenolic content, which significantly enhanced the antioxidant properties of the resulting bioplastics. TW extract incorporation into PLA films increased UV-blocking capability, while keeping the oxygen permeability performance. Mechanical testing revealed improved ductility and toughness in TW extract-containing films compared to pure polylactide film, ascribed to the plasticizing effect of TW polyphenols. Food packaging assays showed effective moisture retention, comparable to low-density polyethylene (LDPE) plastics, antioxidant activity, and excellent bacteria barrier properties allowing the use for food packaging applications. Moreover, migration tests and detection of non-intentionally added substances (NIAS) allowed to establish the safety and regulatory compliance of these bioplastics.

Plant biomass is an attractive precursor to prepare activated carbons with high surface area for CO2 adsorption due to its low-cost and easy regeneration. Despite this interest, there are still remaining questions regarding the optimal processing conditions and the choice of activating agent. Moreover, since plant biomass shows a highly variable proportion of different biopolymers (cellulose, hemicellulose, lignin), it is important to understand the activation effect on each constituent. In this work, carbons obtained from pyrolysis of cellulose were activated using two potassium salts, using two different activation temperatures. The samples were characterized to elucidate the influence of the activation conditions on their CO2 adsorption capacity. In general, all the carbons activated at higher temperature showed higher adsorption capacity. These results are comparable with other carbons derived from biomass described in the bibliography. Among the activated carbons studied, the carbon activated only with KOH exhibits the highest CO2 adsorption capacity at 1 bar meanwhile the highest adsorption capacity at saturation pressure belongs to the carbon activated with larger ratio of KNO3.

Laser-induced graphene (LIG) is widely used to fabricate microsupercapacitors (MSCs) on various sustainable substrates, such as wood, cork, and lignin. However, the fabrication of MSCs, especially high energy density devices on paper, has rarely been reported. In this work, LIG electrodes are fabricated on wax-coated paper, followed by electrochemical deposition of manganese oxide (MnO2). The obtained LIG/MnO2 supercapacitors exhibit a maximum areal capacitance of 86.9 mF cm-2, while a device with pristine LIG electrodes exhibit a capacitance of 9.1 mF cm-2, both measured at a current density of 0.1 mA cm-2. In addition, the supercapacitor exhibits good cycling stability, retaining 80% of its initial capacitance after 1000 charge/discharge cycles at a current density of 1 mA cm-2. Notably, the LIG/MnO2 supercapacitor exhibits an exceptionally high energy density of 7.3 mu Wh cm-2 at a power density of 38.8 mu W cm-2. In summary, a simple, fast, scalable, reproducible, and energy-efficient fabrication method is represented using electrochemical deposition of manganese oxide on paper-based laser-induced graphene, which are natural, abundant, and sustainable materials, paving the way for large-scale production of environmentally friendly supercapacitors.

An easy, fast, scalable, and energy-efficient fabrication method utilizing electrochemical deposition of manganese oxide on paper-based laser-induced graphene is reported. The study demonstrates the potential application of these electrodes in degradable and flexible high-energy density supercapacitors, paving the way for large-scale production of environmentally friendly energy storage devices using natural, abundant, and sustainable materials.

The endeavor of sustainable chemistry has led to significant advancements in green methodologies aimed at minimizing environmental impact while maximizing efficiency. Herein, a straightforward synthesis of benzimidazoles by reductive coupling of o-dinitroarenes with aldehydes is reported for the first time in aqueous media while using a non-noble metal catalyst. This work demonstrates that the combination of nitrogen and phosphorous ligands in the synthesis of supported heteroatom-incorporated Co nanoparticles is crucial for obtaining the desired benzimidazoles. The process achieves >99 % conversion, >99 % chemoselectivity and stability for the reduction of dinitroarenes using water as the solvent and hydrogen as the reductant under mild reaction conditions. The robustness of the catalyst has been investigated using several advanced techniques such as HRTEM, HAADF-STEM, XEDS, EELS, and NAP-XPS. In fact, we have shown that the introduction of N and P dopants prevents metal leaching and the sintering of the cobalt nanoparticles. Finally, to explore the general catalytic performance, a wide range of substituted dinitroarenes and benzaldehydes were evaluated, yielding benzimidazoles with competitive and scalable results, including MBIB (94 % yield), which is a compound of pharmaceutical interest.

Efficient hydrogen generation from water-splitting is widely acknowledged as a priority route to promote the hydrogen economy. Anion exchange membrane water electrolyzers (AEMWE) offer multiple advantages in improving performance and minimizing the cost limitations of current electrolysis technologies. However, the persistence of issues related to the limited electrocatalytic activity of such materials and their poor stability under operating conditions makes developing highly active, stable, platinum-group-metal-free electrocatalysts for oxygen evolution reaction (OER) necessary. We report the development of Prussian blue analogues (PBA)-derived NiFe-based electrocatalysts through a mild aqueous phase precipitation method, followed by thermal stabilization and phosphorus doping. The formation of the NiFe-PBA-precursor with a framework nanocubic Ni(II)[Fe(III)(CN)₆]_2/3 structure was confirmed by X-ray diffraction, scanning electron microscopy, and inductively coupled plasma analysis. The NiFe-PBA-precursor was subjected to thermal stabilization and phosphorus doping to provide the material with enhanced OER catalytic activity and stability. The existence of OER active sites based on NiFe and NiFeP has been revealed by transmission electron microscopy, X-ray photoelectron spectroscopy, and electrochemical characterization in a three-electrode cell configuration in a 1 M KOH electrolyte. NiFe-PBA and NiFeP-PBA were assembled at the anode side of an AEMWE, resulting in an excellent electrochemical performance both in terms of current density at 2.0 V using 1 M KOH (1.21 A cm⁻²) and durability, outperforming the benchmark catalyst.

VOx/TiO₂ catalysts with various theorical monolayer values have been prepared and used to study, for the first time, the effect of vanadium loading in the selective oxidation of glucose to formic acid. Monomeric or isolated vanadia species dominate at low loadings, evolving into polymeric chains at higher concentrations, while crystalline V₂O₅ is observed at loadings over the theoretical monolayer value. Their characterization by XRD, BET, ICP, DRIFTS, Raman, UV–vis, H₂-TPR and NH₃-TPD reveal distinct physicochemical characteristics influenced by the formed vanadia species, impacting sample acidity, reducibility, and catalytic activity. All catalysts exhibit significant activity, forming formic acid as the main product in the liquid phase and reaching a peak formic acid yield of 42 %. Post-reaction analysis reveals that the leaching-prone crystalline V₂O₅ compromises catalyst stability while isolated vanadia species demonstrate superior catalytic activity and leaching resistance. The findings of this study provide a strong basis for the development of a heterogeneous vanadia catalyst with improved interaction with the support.

Two series of open metal site MOFs, HKUST-1 and MIL-100(Fe), have been successfully prepared using different methods of synthesis. Their features depend on the synthetic route as well as their role play in different environmental applications. The stability and performance of these BTC-based MOFs have been tested bearing in mind Congo Red (CR) removal, humidity adsorption and iodine capture and release. HKUST-1 and MIL-100(Fe) samples could offer a remarkable role in the adsorption of CR from aqueous solutions. However, the lability of HKUST-1 in water is revealed as a drawback for its reutilization in both static and agitation conditions. The former contrasts to the stability under ambient moisture. MIL-100(Fe) shows promising properties in both CR adsorption in aqueous solutions and humidity adsorption. Nonetheless, the performance largely depends on the synthesis conditions. Although CR removal is based on surface interaction, there is a relation between the adsorpted quantity and the specific surface area. The size and nature of iodine allows the diffusion in the pores of both HKUST-1 and MIL-100(Fe) MOFs. This way, the uptake of iodine is driving by the porosity and surface area of samples rather than their inherent nature. As a rule, the results of this work indicate that not only is it important the specific nature of the MOF chosen for a given application but also the way in which it has been synthesized and the conditions in which they are used. MIL-100(Fe)-R is revealed as the best suitable candidate to be used as a sorbent for CR in aqueous solutions, moisture and I2 gas.

In recent years, the implementation of CO2 capture systems has increased. To reduce the costs and the footprint of the processes, different industrial wastes are successfully proposed for CO2 capture, such as gypsum from desulfurization units. This gypsum undergoes an aqueous carbonation process for CO2 capture, producing an added-value solid material that can be valorized. In this work, panels have been manufactured with a replacement of (5 and 20%) commercial gypsum and all the compositions kept the water/solid ratio constant (0.45). The density, surface hardness, resistance to compression, bending, and fire resistance of 2 cm thick panels have been determined. The addition of the waste after the CO2 capture diminishes the density and mechanical strength. However, it fulfills the requirements of the different European regulations and diminishes 56% of the thermal conductivity when 20%wt of waste is used. Although the CO2 waste is decomposed endothermically at 650 degrees C, the fire resistance decreases by 18% when 20%wt. is added, which allows us to establish that these wastes can be used in fire-resistant panels. An environmental life cycle assessment was conducted by analyzing a recycling case in Spain. The results indicate that the material with CO2 capture waste offers no environmental advantage over gypsum unless the production plant is located within 200 km of the waste source, with transportation being the key factor.

Replacing homogeneous catalytic processes by heterogeneous routes based on the utilization of solid catalysts is of great interest from an environmental point of view. Owing to their genuine pore structure, zeolites such as mordenites (MOR) have emerged as game-changing materials to enable the heterogenization of catalytic processes including methanol carbonylation. Cu-exchange zeolites take the edge over pristine zeolites, leading to enhanced catalytic performance in terms of greater activity, selectivity, and stability. Herein, the overall catalytic activity and stability can be modulated upon controlling the environment and location of copper active sites in zeolites. In this study, Cu-exchanged mordenites were strategically synthesized to investigate the role of Cu location inside of MOR cavities under working conditions by means of in situ/operando infrared (IR) spectroscopic studies. The results obtained revealed that a major proportion of Cu in the MR-8 cavities notably enhances the activity and stability of the catalyst. This study provides crucial insights for fine-tuning zeolite catalysts to achieve the heterogenization of homogeneous carbonylation processes.

Embracing a circular economy in the textile industry represents a crucial step toward sustainability, where fashion and textile sectors contribute significantly to CO2 emissions. However, transitioning from a linear “take-make-waste” model to circularity, poses multifaceted challenges, that highlight the staggering volume of annual textile waste surpassing industry predictions, thus emphasizing the urgent need for comprehensive strategies. Despite advancements in recycling technologies, challenges persist in collecting and sorting textile waste, where fragmentation in waste management and recycling processes hinders effective management of post-consumer waste. Addressing these challenges demands elevated efforts in collection, sorting, and pre-processing, alongside regulatory interventions to drive enhanced waste collection and circular business models. Efforts are underway to promote sustainable textile recycling, with initiatives like the EU’s Sustainable and Circular Textiles Strategy aiming to reduce reliance on virgin resources. However, achieving a circular textile market in the near future requires collaborative action and innovative solutions. Though challenges in scaling and technological limitations still remain, recent breakthroughs in textile-recycling technologies offer promise, signaling a shift toward scalable and sustainable alternatives to virgin fibers, where bio-based chemical processes, and thermochemical recycling processes present transformative opportunities. Where, bold scaling targets, collaborative efforts, and short-term funding support narrated in this perspective article are imperative to accelerate the transition to a circular textile economy, thus delving into the pivotal role of textile recycling, tracing the evolution of recycling technologies, and addressing critical challenges hindering widespread adoption.

We report the development of a multimodal lanthanide vanadate system suitable as dual T₁-T₂ MRI contrast agent as well as a luminescent imaging probe in the near-infrared region, using Dy³⁺ and Gd³⁺ as T₂ and T₁ components, respectively, and Nd³⁺ as the luminescent center. The vanadate matrix was chosen to avoid the undesired solubility associated to previously reported fluoride-based contrast agents. With such aim, we first optimized the design of the MRI system by comparatively evaluating the magnetic relaxivities of two different architectures consisting of i) uniform NPs incorporating both paramagnetic cations in solid solution (single-phase NPs), and ii) core-shell NPs consisting of a DyVO₄ core coated with a homogeneous GdVO₄ shell (DyVO₄@GdVO₄). We found that, although both samples presented magnetic relaxivity properties that make them adequate for their use as dual T₁-T₂ contrast agents for magnetic resonance imaging, the core-shell architecture would be more suitable because of their higher magnetic relaxivity values. Secondly, to prepare the multimodal system, the GdVO₄ layer of such optimal dual T₁-T₂ MRI probe was doped with Nd³⁺ cations. An inert YVO₄ intermediate shell was also introduced between the cores and the outer layer aiming to avoid energy transfer from Nd³⁺ to Dy³⁺, which would cause luminescence quenching. These core-shell-shell nanoparticles showed magnetic relaxivity values similar to those of the core-shell system and an intense luminescence in the near-infrared region. Moreover, they were dispersible and chemically stable under conditions that mimic the physiological media, and they were nontoxic for cells. Therefore, such multimodal nanoparticles meet the main requirements for their use as a dual T₁-T₂ contrast agent for magnetic resonance imaging and as a probe for luminescent imaging in the near-infrared region.

This study presents a novel approach for boosting the selectivity of 5-hydroxymethylfurfural (HMF) production from glucose through electrochemical modification of graphite materials. Three distinct graphitic substrates were subjected to controlled electrochemical treatments utilizing sodium sulfate or phosphoric acid as electrolytes. The process expanded the graphite particles/pieces and introduced oxygenated functional groups to the exposed surfaces while preserving the structural integrity of the bulk material. The resulting modifications influenced the type and quantity of Lewis and Brønsted acidic sites, providing exhaustive control over reaction pathways leading to HMF. This electrochemically modified graphite demonstrated superior tunability compared to traditional metal-based catalysts, enabling dynamic optimization of reaction conditions for enhanced HMF yield. The controlled introduction of functional groups facilitated the tailoring of active sites, significantly impacting the kinetics of glucose conversion and achieving HMF selectivity up to 95%. This level of precision in controlling catalytic properties is essential for maximizing HMF yield while minimizing undesired by-product formation, addressing a critical challenge in HMF production.

NiFe electrocatalysts are among the most active phases for water splitting with regard to the alkaline oxygen evolution reaction (OER). The interplay between Ni and Fe, both at the surface and in the subsurface of the catalyst, is crucial to understanding such outstanding properties and remains a subject of debate. Various phenomena, ranging from the formation of oxides/(oxy)hydroxides to the associated segregation of certain species, occur during the electrochemical reactions and add another dimension of complexity that hinders the rational design of electrodes for water splitting. In this work, we have developed the procedure for the quantification of chemical depth profiling by XPS/HAXPES measurements and applied it to two NiFe electrodes with different porosities. The main outcome of this study is related to the surface reconstruction of the electrodes during the OER, followed at two different depths by means of X-ray photoelectron spectroscopy. We find that Fe initially segregates at the surface when exposed to ambient conditions, resulting in the formation of an inactive FeOx phase. In addition, the porosity of the catalyst plays a significant role in the segregation process and thus in the performance of the electrode. In particular, the higher porosity of the nanostructured sample is responsible for a more pronounced diffusion of Fe from the subsurface to the surface with a more effective suppression of the activity of the Ni1–xFexOOH phase. These results highlight the importance of the fact that the chemical state of the surface of a multielement system is a snapshot in time, dependent on both external parameters, such as the applied potential and the adjacent electrolyte, and the underlying bulk properties accessible with HAXPES.

Integrated carbon dioxide capture and utilization (ICCU) technology is being developed to address the challenge of increasing atmospheric CO2 levels. Dual function materials (DFMs) are designed with catalytic and adsorbent components that enable the capture and utilization of CO2 within a single reactor. In this investigation, we systematically evaluated the performance of NiRu-DFMs incorporating oxides of Ca, Na, or a combination to identify effects on both activity and selectivity. Our findings underscore not only the role of adsorbent selection in dictating the overall performance of DFMs but also the pretreatment conditions (in situ reduction). Notably, the highest methanation activity is observed on an as-synthesized (oxidized) 10% Ca-DFM (223.21 mu mol/gDFM) at 380 degrees C, surpassing all other as-synthesized or reduced DFMs. This study sheds light on the relationships between composition, pretreatment, temperature, and performance in DFMs, offering valuable insights into the advancement of new compositions for DFMs.

Early results on the plasma deposition of dielectric thin films on acoustic wave (AW) activated substrates revealed a densification pattern arisen from the focusing of plasma ions and their impact on specific areas of the piezoelectric substrate. Herein, we extend this methodology to tailor the plasma deposition of metals onto AW-activated LiNbO₃ piezoelectric substrates. Our investigation reveals the tracking of the initial stages of nanoparticle (NP) formation and growth during the submonolayer deposition of silver. We elucidate the specific role of AW activation in reducing particle size, enhancing particle circularity, and retarding NP agglomeration and account for the physical phenomena making these processes differ from those occurring on non-activated substrates. We provide a comparative analysis of the results obtained under two representative plasma conditions: diode DC sputtering and magnetron sputtering. In the latter case, the AW activation gives rise to a 2D pattern of domains with different amounts of silver and a distinct size and circularity for the silver NPs. This difference was attributed to the specific characteristics of the plasma sheath formed onto the substrate in each case. The possibilities of tuning the plasmon resonance absorption of silver NPs by AW activation of the sputtering deposition process are discussed.

Combining Carbon Capture and Storage (CCS) with producing competitive secondary raw materials is key to decarbonizing industry and reducing resource extraction. Biogas upgrading to biomethane stand out as an alternative, but a significant gap remains in integrating this process within a circular economy framework. This issue has been recently addressed by a process that integrates biogas upgrading via caustic absorption with the production of Precipitated Calcium Carbonate (PCC) and the recovery of sodium hydroxide from waste brine solution using membrane technologies. The profitability of this approach depends on the quality of the PCC, a critical factor that this work addresses. By characterizing PCC is determined whether trace compounds in biogas contaminate the PCC and potentially affect its commercial value. It also examines the CO2 absorption process and analyzes the aqueous samples from the filtration phase of the PCC slurry. Results confirm the high purity of PCC obtained from biogas treatment using Raman spectroscopy, X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). The analyses show that the PCC is pure calcium carbonate, mainly in the stable calcite form, with a typical tetrahedral morphology and no detectable impurities. Characterization of aqueous solutions revealed organic trace compounds from biogas, with TOC concentrations of 9.7 (+/- 6.4) and 16.0 (+/- 8) mg C/l. Silicon measurements showed similar concentrations in the absorbent solution and filtrated PCC slurry. Additionally, ammonia escapes as gas, and hydrogen sulfide in the biogas likely contributed to sulfate salt formation. Analysis of the COQ absorption shows a first-order reaction with OH-, where the amount of COQ absorbed (46.3-50.0 g) closely matches the theoretical value of 48 g. The study reveals that most of the biogas impurities dissolve into the aqueous solution, being crucial for future studies and downstream membrane treatments, and the PCC is unaffected by these impurities with a purity suitable for commercial applications.

Surface engineering through the deposition of advanced coatings, particularly multilayer coatings has gained significant interest for enhancing the performance of coated parts. The incorporation of Si into TiN coatings has shown promise for improving hardness, oxidation resistance, and thermal stability, while high-power impulse magnetron sputtering (HiPIMS) has emerged as a technique to deposit coatings with exceptional properties. However, TiN/CrN and TiSiN/CrN coatings deposited by HiPIMS remain relatively unexplored. In this study, different TiN/CrN and TiSiN/CrN multilayer coatings with different bilayer periods from 5 to 85 nm were deposited using an industrial-scale HiPIMS reactor, and their microstructure and mechanical properties were investigated using advanced characterization techniques. Results revealed successful deposition of smooth and compact coatings with controlled bilayer periods. X-ray diffraction analysis showed separate crystalline phases for coatings with high bilayer periods, while those with smaller bilayer periods exhibited peak-overlapping and superlattice overtones, especially for the TiN/CrN coatings. Epitaxial grain growth was confirmed by highresolution transmission electron microscopy (HRTEM). HRTEM and electron energy-loss spectroscopy measurements confirmed Si incorporation into the TiN crystal lattice of TiSiN/CrN coatings reducing the crystallinity, especially for coatings with smaller bilayer periods. Nanoindentation tests revealed that coatings with a bilayer period of 15-20 nm displayed the highest hardness values regardless of the composition. The mechanical properties of the TiSiN/CrN coatings showed no improvement over those of the TiN/CrN coatings, attributed to the Si induced amorphization of the Ti(Si)N phase and the absence of SiNx phase segregation within the TiN nanocrystals in these coatings. These findings provide valuable insights into the microstructure and mechanical properties of TiN/CrN and TiSiN/CrN multilayer coatings deposited by HiPIMS in an industrial scale reactor, paving the way for their application in various industrial sectors.

Novel zinc-doped Metal-Organic Framework based on MIL53(Fe) (Zn-MIL53(Fe)) has been successfully synthesised in one-step, exhibiting dual applications as adsorbent and catalyst. Initially, the adsorption capacity of MIL53(Fe) and Zn-MIL53(Fe) for removing Rhodamine B was assessed through kinetic and isotherm studies. The bimetallic variant exhibited superior performance, showcasing enhanced adsorption capabilities, particularly in the context of its physical interaction under natural pH. After that, the catalytic activity of both synthesised materials was evaluated to generate sulphate radicals by activating PeroxyMonoSulphate (PMS). It was also demonstrated that Zn-MIL53(Fe) exhibited the best catalytic activity being optimised using response surface methodology for Rhodamine B degradation (0.11 mM PMS and 43.2 mg Zn-MIL53(Fe)). Under optimal conditions, favourable outcomes were attained, facilitating the degradation of Rhodamine B, Fluoxetine, and Sulfamethoxazole by 93, 99, and 75 %, respectively. Furthermore, the operational stability of the Zn-MIL53(Fe) was verified, as it remains structurally and catalytically intact after different cycles.

In heterogeneous photocatalysis, different reactive species generated from the excitation of the semiconductor are responsible for the degradation of different contaminants in aqueous solution. In order to evaluate the influence of each of these reactive species on the photocatalysis process, it is common to perform an analysis using different chemical compounds, which (in theory) react selectively with only one reactive species, preventing this species from participating in the process. Questioning this analysis is the aim of this work and the reasons that lead us to this will be described and discussed. For this, different investigations were selected where this analysis was carried out on two model substrates, Rhodamine B and Phenol. With this, it was possible to determine which compounds are most used as scavengers for the different reactive species, and how these compounds influence the photodegradation process. It was possible to shown that none of the commonly used scavengers react selectively with only one reactive species, since it can also influence other reactions, either by reacting with other reactive species, with the surface of the catalyst, or with the substrate under study, among others. In our opinion, the conclusions obtained by using scavenger analysis should be carefully considered, and the compounds used should be renamed as interfering species of the photocatalytic process.

The transformative power of CO2 methanation can efficiently transform greenhouse gases into high-value products, aligning with the carbon neutrality goals. However, achieving this target at low temperature requires cumbersome efforts in designing catalysts that possess high reactivity and selectivity. Focusing on understanding the pivotal role of alkaline (such as Ca) sites in catalyzing these reactions at lower temperature could be a way of strategically creating oxygen vacancies with varying activity gradients. Designing CaCe-SG via a sol-gel method in the current study to integrate Ca into the CeO2 lattice marked the highly active moderate-strength alkaline centers which resulted in the intrinsic activity soaring by an impressive 400% compared to the conventional Ni/CeO2 catalysts. Supported by H-2-TPD, Raman, and XPS analyses, a crucial revelation was unveiled where Ca modification induced a surge in the dispersion of active Ni species on Ni/CaCe-SG catalysts, thereby enhancing the abundant surface oxygen vacancies. In situ infrared spectroscopy further confirmed that the modified catalyst diligently followed the reaction pathway of CO3H* -> HCOO* -> CH4, culminating in the CO2 methanation activity with a low-temperature catalyst via the meticulous optimization of synthesis methods that propelled the process forward to the anticipated oxygen vacancy-induced moderate-strength alkaline centers.

Triboelectric nanogenerators (TENGs) have emerged as potential energy sources, as they are capable of harvesting energy from low-frequency mechanical actions such as biological movements, moving parts of machines, mild wind, rain droplets, and others. However, periodic mechanical motion can have a detrimental effect on the triboelectric materials that constitute a TENG device. This study introduces a self-healable triboelectric layer consisting of an Ecoflex-coated self-healable polydimethylsiloxane (SH-PDMS) polymer that can autonomously repair mechanical injury at room temperature and regain its functionality. Different compositions of bis(3-aminopropyl)-terminated PDMS and 1,3,5-triformylbenzene were used to synthesize SH-PDMS films to determine the optimum healing time. The SH-PDMS films contain reversible imine bonds that break when the material is damaged and are subsequently restored by an autonomous healing process. However, the inherent stickiness of the SH-PDMS surface itself renders the material unsuitable for application in TENGs despite its attractive self-healing capability. We show that spin-coating a thin layer (approximate to 32 mu m) of Ecoflex on top of the SH-PDMS eliminates the stickiness issue while retaining the functionality of a triboelectric material. TENGs based on Ecoflex/SH-PDMS and nylon 6 films show excellent output and fatigue performance. Even after incisions were introduced at several locations in the Ecoflex/SH-PDMS film, the TENG spontaneously attained its original output performance after a period of 24 h of healing. This study presents a viable approach to enhancing the longevity of TENGs to harvest energy from continuous mechanical actions, paving the way for durable, self-healable mechanical energy harvesters.