Artículos SCI

Abstract

In this study, the potential of a bimetallic Metal-Organic Framework Zn-MIL53(Fe) for electro-Fenton catalysis was evaluated. After the material characterisation, its catalytic activity was validated in Fenton reaction to degrade a model organic pollutant: Rhodamine B. After that, the evaluation of Zn-MIL53(Fe) as electro-Fenton catalyst was performed and improved outcomes were reached by electro-Fenton regarding anodic oxidation. Then, electro-Fenton treatment optimisation was carried out using response surface methodology assays considering different catalyst dosages (7.2-43.2 mg), current intensities (5-45 mA) and treatment time (30-90 min) in a volume of 0.1 L. Under optimal conditions, a degradation rate over 90 % for Fluoxetine and Sulfamethoxazole in synthetic wastewater was achieved within 90 min, using graphite sheet as anode and nickel foam as cathode (25 mA), with a catalyst dosage of 43.2 mg in a volume of 0.1 L. Additionally, its application in the pathogen inactivation was evaluated using different gram-negative and gram-positive bacteria. Complete eliminations of both types of bacteria were reached in 5 min using the optimal conditions. In the end, Zn-MIL53(Fe) was proven as a reusable material, capable of performing 3 complete cycles of electro-Fenton treatment for both types of pollutants bacteria and pharmaceuticals, which makes it a promising candidate for more efficient wastewater treatment applications which involve the Fenton reaction.

Abstract

Microplastics are an emerging pollutant of concern. Many microplastics in the waters arise from washing synthetic textiles in residential and commercial washing machines. The present research evaluated the upcycling of this waste to carbon materials by hydrothermal carbonization. Real microfiber waste was collected using clothes washer and dryer microfilters. Via temperature and residence time screening (200 degrees C, 250 degrees C, 300 degrees C and 1 h, 4 h, 8 h) two temperatures of interest were determined (250 degrees C and 300 degrees C) for hydrothermal carbonization, for a residence time of 4 h. The results obtained in this research demonstrated that by varying the reaction conditions carbon production can be tailored, producing amorphous carbon or graphene/graphite. To this end, Raman spectroscopy results indicated the production of carbon nanomaterials; smaller particle sizes were detected after 250 degrees C-4h and 300 degrees C-4h treatments, (29.6 nm and 33.1 nm, respectively). Transforming microfibers into useful carbon nanoparticles via hydrothermal carbonization prolongs their lifecycle and mitigates environmental pollution. This process is an intriguing method of incorporating textile residue (microfibers) into the circular economy, where resources are perpetually recycled, and waste is avoided.

Abstract

The thermal memory effect, TME, has been studied in Ni₅₅Fe₁₉Ga₂₆ shape memory alloys, fabricated as ribbons via melt-spinning and as pellets via arc-melting, to evaluate its dependence on the martensitic structure and the macrostructure of the samples. When the reverse martensitic transformation is interrupted, a kinetic delay in the subsequent complete transformation is only evident in the ribbon samples, where the 14M modulated structure is the dominant phase. In contrast, degradation of the modulated structure or the presence of the γ phase significantly reduces the observed TME. In such cases, the magnitude of the TME approaches the detection limits of commercial calorimeters, and only high-resolution calorimeter at very low heating rate (40 mK h⁻¹) can show the effect. Following the kinetic arrest and subsequent cooling, the reverse martensitic transformation was completed at several heating rates to confirm the athermal nature of the phenomenon.

Abstract

Dye Sensitized Solar Cells (DSSCs) have recently gained renewed interest for their potential in indoor light harvesting and powering wireless devices. However, to fully exploit their potential, crucial aspects require further attention, in particular, the improvement of spectral compatibility and low-light harvesting mechanisms, as well as the development of efficient photoanodes through high-yield scalable methods. In this article, we propose the use of nanocomposite photoanodes integrating mesoporous TiO2 nanoparticles, ITO nanotubes (NT), and anatase TiO2 shells (ITO@TiO2 NT) prepared by step-by-step method relying on mild temperature conditions and avoiding toxic precursors. These photoanodes outperform previous attempts to implement low-dimensional ITO and ITO@TiO2 nanowires and nanotubes for outdoor light conversion, demonstrating a power conversion efficiency under low artificial light intensity of 24 % for at 0.014 mW cm-2, a 166 % increase compared to the conventional architectures. Advanced microstructural, optical, and electrochemical characterizations have revealed that the strong scattering effect of the light in the visible range coupled with enhanced charge collection at low-intensity illumination are the essential mechanisms responsible for such enhanced energy conversion. Remarkably, our devices retain up to 90 % of the normal incidence efficiency even under glancing illumination, while conventional reference devices retain only 30 %.

Abstract

Stability descriptors for the formation of solid solutions can be divided into two categories: inspired by Hume–Rothery rules (HRR) and derived from thermodynamic approaches. Herein, HRRs are extended from binary to high-entropy alloys (HEAs) focusing on compositions prepared by ball milling. Parameters describing stability criteria are interrelated and implicitly account for the microstrains’ storage energy, more determinant than entropy increase in stabilization of HEAs and more effective in bcc structures than close-packed ones (fcc and hcp). An effective temperature, T_eff, is defined as the ratio between increase in metallic bonding energy of solid solutions with respect to segregated pure constituents and configurational entropy. This versatile parameter is used as a threshold for stabilization of HEAs at equilibrium and out of equilibrium. When T_eff is below room temperature, HEA would be stable at equilibrium. When T_eff is below melting temperature, HEA would be obtained by rapid quenching. Limitations related to electronegativity differences remain valid in mechanically alloyed solid solutions. However, ball milling broadens the allowed differences in atomic size to form HEA. Moreover, thermodynamic criteria can be surpassed in these systems, allowing the formation of single-phase solid solutions beyond the compositional range predicted by those criteria.

Abstract

This work presents a straightforward strategy for achieving specific overheating during flash experiments by adjusting the initial electrical parameters. To do that, an extensive experimental analysis was performed to evaluate the temperature evolution of dense ZnO specimens during controlled-current ramping at different furnace temperatures, which in turn modified the initial electrical resistance of the sample. A detailed electrical explanation of controlled-current ramp flash processes is provided and, for the first time, a practical equivalence between current-ramp and temperature-ramp flash methodologies is established. By parameterizing the experiments in terms of an effective power density, a consistent heating pattern following the blackbody radiation trend was identified, despite the different electrical characteristics of each experiment. Finally, a “flash heating map” is introduced, which can be used to determine the starting electrical parameters necessary to achieve a specific temperature increase, whether employing current or temperature ramps.

Abstract

Polylactide-based materials represent a promising bio-based alternative to traditional food packaging polymers. However, their widespread use is still limited due to significant drawbacks, such as brittleness, high gas permeability, and biodegradability only under specific conditions. This work introduces fully bio-based Triphenyl Acetic Glyceroate (TPAG), synthesized through a solvent-free and mild conditions valorization of glycerol and phenylacetic acid, as a polylactide (PLA) plasticizer and multiple property-enhancer for extending foodstuff shelf-life. After optimizing TPAG synthesis and confirming its structure through FT-IR and NMR, PLA-based films are prepared at different TPAG contents (0, 5, 10, and 20 phr). Detailed investigations of the films' thermal, mechanical, optical, hydrodynamic, barrier, antioxidant, antibacterial, migration, and biodegradation characteristics are carried out. TPAG shows a significant plasticizing effect while maintaining high transparency and improving PLA's antioxidant, antibacterial and UV-blocking activities. Moreover, a notable lowering in oxygen and water vapor transmission rate is detected, revealing water vapor barrier properties closer to LDPE. Migration tests verify the material's compliance with European regulations up to 10 phr, and BOD assessments in seawater indicate improved biodegradability. Fresh food preservation is evaluated on pear slices, showing limited variation of color, acidity, antioxidant power, and weight loss comparable to LDPE-based commercial packaging.

Abstract

The influence of the characteristic features and firing temperature on the ceramic properties of raw kaolin samples were examined studying a wide range of firing temperatures (1000–1500 ºC). The techniques of investigation have been particle size analysis, Transmission Electron Microscopy (TEM), X-ray powder Diffraction (XRD), X-ray Fluorescence analysis (XRF), and Thermal Analysis using Termodilatometry (TD), Thermalgravimetric analysis (TGA) and Differential Thermal Analysis (DTA). Uniaxial pressed cylindric bodies were obtained and fired from 1000 to 1500 °C/2 h. TEM allowed investigate morphological differences and identification of kaolinite and halloysite. The mineralogical analysis indicated that the kaolinite content is high (80–90 wt%). The contents of oxide impurities are relatively low although in a sample is 7.6 wt% on a calcined basis. The characteristic sharp DTA exothermic effect of kaolinite was observed in the range 900–1000 °C. The ceramic properties of the group of kaolin samples has been determined: linear firing shrinkage, water absorption capacity, apparent density and open porosity. Sintering diagrams allowed investigate the progressive decrease of water absorption and the increase of firing shrinkage. In some kaolin samples the water absorption reached zero at 1450–1500 ^ᵒC. High sintering temperatures have been observed when kaolinite is present in high contents and the fluxes content is low. The maximum values of apparent density were determined, with a sample with the highest value (2.75 ± 0.10 g/cm³). The open porosity changes from ∼ 34–38 % at 1000 ᵒC up to zero or minimum values (< 3 %) at 1500 ^ᵒC. This behaviour is associated to the progressive sintering of the particles and filling of pores by glassy phase originated by the presence of fluxes and the influence of a low particle size. The formation of mullite and cristobalite by firing have been studied by XRD. Mullite has been detected from 1000 to 1100 ᵒC and the crystals developed as increasing firing temperatures. Cristobalite (α-cristobalite) has been identified at 1200–1300 ºC. The presence of an alkaline melt could impede the crystallization of cristobalite. This study presents a comparative research because all these commercial kaolin samples have been examined under the same experimental conditions. Consequently, the results have allowed to provide new data about raw kaolin powders with high kaolinite content in the range 80–90 wt%.

Abstract

Plasma treatment of seeds is an efficient procedure to accelerate germination, to improve initial stages of plant growth, and for protection against pathogen infection. Most studies relate these beneficial effects with biochemical modifications affecting the metabolism and genetic growth factors of seeds and young plants. Using barley seeds, in this work, we investigate the redistribution of ions in the seed surface upon their treatment with cold air plasmas. In addition, we investigate the effect of plasma in the lixiviation of ions through the seeds' hull when they are immersed in water. Ion redistribution in the outer layers of air plasma-treated seeds has been experimentally determined through X-ray photoelectron spectroscopy analysis in combination with in-depth chemical profiling with gas cluster ion beams. The results show that in the shallowest layers of the seed hull (at least up to a depth of similar to 100 nm) there is an enrichment of K+ and Ca2+ ions, in addition to changes in the O/C and N/C atomic ratios. These data have been confirmed by the electron microscopy/fluorescence analysis of seed cuts. Observations have been accounted for by a Monte Carlo model, simulating the electrostatic interactions that develop between the negative charge accumulated at the seed surface due to the interaction with the plasma sheath and the positive ions existing in the interior. Furthermore, it is shown that upon water immersion of plasma-treated seeds mobilized ions tend to lixiviate more efficiently than in pristine seeds. The detection of a significant concentration of NO3 - anions in the water has been attributed to a secondary reaction of nitrogen species incorporated into the seeds during plasma exposure with reactive oxygen species formed on their surface during this treatment. The implications of these findings for the improvement of the germination capacity of seeds are discussed.

Abstract

Magnetron sputtering (MS) is an emerging technique to prepare electrocatalysts for oxygen and hydrogen evolution reactions that take place in alkaline water electrolysis. It is a physical vapour deposition method that provides a strict control over the composition, chemical state, and microstructure. It permits to adjust complex stoichiometries and guarantees reproducibility. This technology allows to deposit electrocatalysts on suitable current collectors to get anode and cathode electrodes in a one-step process. Furthermore, MS is an environment friendly technology with easy scalability for industrial electrode production. Additionally, when operated in an oblique angle deposition configuration, it allows precise control of the microstructure of the deposits that can be tuned from compact to mesoporous. On this brief review we discuss recent studies on the field showing the possibility of using MS for the preparation of catalyst layers with complex compositions, bi-layer structure configurations, and bimetallic, trimetallic, and multicomponent alloys.

Abstract

In this paper, we investigate the Casimir-Lifshitz free energy mechanism that governs both ice growth and melting near metal surfaces, with a particular focus on the role of oxidation. Our study reveals that metals such as gold, iron, and aluminum induce incomplete premelting, resulting in micron-sized liquid water layers when in contact with ice. These layers could have significant implications for the defrosting of metallic surfaces. When exposed to water vapor at the triple point, aluminum and other metals can induce the formation of notably thick layers of either liquid water or ice, which can theoretically become infinitely thick if other interactions are disregarded. However, when aluminum undergoes oxidation to form alumina, its behavior changes dramatically. Alumina surfaces cause complete melting when in direct contact with bulk ice and result in only micron-sized layers of water or ice in vapor conditions. In contrast, magnetite, the oxidized form of iron, retains metalliclike behavior due to its high dielectric constant, similar to other metals, and continues to support thick layers of water or ice. This distinction highlights the significant influence of oxidation on the dynamics of ice growth and melting near different metal surfaces.

Abstract

Metal-Organic frameworks (MOFs) are promising candidates for advanced photocatalytically active materials. These porous crystalline compounds have large active surface areas and structural tunability and are thus highly competitive with oxides, the well-established material class for photocatalysis. However, due to their complex organic and coordination chemistry composition, photophysical mechanisms involved in the photocatalytic processes in MOFs are still not well understood. Employing electron paramagnetic resonance (EPR) spectroscopy and time-resolved photoluminescence spectroscopy (trPL), the fundamental processes of electron and hole generation are investigated, as well as capture events that lead to the formation of various radical species in UiO-66, an archetypical MOF photocatalyst. A manifold of photoinduced electron spin centers is detected, which is subsequently analyzed and identified with the help of density-functional theory (DFT) calculations. Under UV illumination, the symmetry, g-tensors, and lifetimes of three distinct contributions are revealed: a surface O2-radical, a light-induced electron-hole pair, and a triplet exciton. Notably, the latter is found to emit (delayed) fluorescence. The findings provide new insights into the photoinduced charge transfer processes, which are the basis of photocatalytic activity in UiO-66. This sets the stage for further studies on photogenerated spin centers in this and similar MOF materials.

Abstract

One of the biggest players in the world economy is the naval industry, which mainly controls the merchandise transportation sector. Any issue with ships could represent millions of USD of loss and increases in the cost of goods for the population worldwide. Two main problems which this industry has fought are corrosion and biofouling. Lastly, the pollution of the sea has gained importance, and more strict policies have been applied regarding the use of certain products by this industry. One of these is paintings, which represented this industry's definitive solution to avoid the mentioned problems for a long time. This situation allowed to explore other solutions like PVD coatings through multifunctional coatings. Zirconium nitride has been demonstrated to be useful in resisting corrosion with reliable mechanical properties. However, this material does not possess antimicrobial action. The present study presents a nanostructured coating combining ZrN with Cu, which works as a biocide, contributing to the desired multifunctionality. The developed coating was obtained using a hybrid magnetron co-sputtering employing High-power impulse (HiPIMS) and direct current (DCMS) power sources under a reactive atmosphere. SEM, EDX, XRD and Raman spectroscopy were used to assess the physico-chemical properties of the coatings. Besides, depth-sensing nano-indentation explored the mechanical properties. The tribological performance was tested by a reciprocating tribometer under dry and wet (with 3.5 % w/w NaCl solution) contact conditions and employing a soda lime glass ball as a counterbody. The results showed that adding Cu to ZrN through this technology resulted in a limited hardness reduction from 19 (pure ZrN) to 14 GPa. Also, the chemical activation with NaOCl solution softens the obtained coating and, together with the saline solution, influences the wear resistance. However, the nanostructured coating has been demonstrated to be suitable for use under real conditions, without loss of its protection over the used substrate. It opens a new possibility of a solution for the naval industry.

Abstract

This study presents the photocatalytic degradation of the aminophosphonate ethylenediaminetetra(methylenephosphonic acid) (EDTMP) with a range of different doped nanoparticles (NP). The photocatalysts were based on TiO2 benchmark P25 and gold (Au) doped either with sodium (Na), potassium (K) or yttrium (Y). The synthesized photocatalysts were characterized via TEM, XRF, XRD, UV-DRS (band gap estimation) and N2-phys- isorption. Photocatalytic pre-screening at pH values of 3, 7 and 10 indicated highest o-PO4 release of EDTMP at pH 7 and 10 for NP either doped with K or Y. The results of LC/MS analysis showed that the NPs doped with 5 % Y (Au2/Y5/P25) resulted in the fastest degradation of EDTMP. The target compound was completely degraded within 60 min, 4 times faster than photochemical treatment of unadulterated EDTMP. Importantly, also the transformation products were accelerated by the photocatalytic treatment with Au2/P25 either doped with 5 % Y or 10 % K. The results of scavenger experiments indicated that the enhanced photocatalytic degradation of EDTMP is primarily attributable to the presence of hydroxyl radicals in the bulk and to a lesser extent to center dot O2- and electron-holes (h+) at the surface of the catalysts. The study demonstrates that the catalytic efficiency of TiO2 nanocomposites is significantly influenced by the choice of dopants, which affect particle size, band gap, and photocatalytic activity. Yttrium at low concentrations (i.e., 5 wt% Y) doping emerged as particularly effective, enhancing both the visible light absorption and h+ separation, leading to superior photocatalytic performance in the degradation of EDTMP. The Au content also plays a crucial role in enhancing the photocatalytic efficiency. However, the combination of Au and Na doping was found to be less effective for this photocatalysis in aqueous media, potentially due to larger particle sizes and insufficient dopant contents. In conclusion, the findings emphasise the necessity of optimising both the selection of dopants and the design of catalysts in order to enhance photocatalytic applications.

Abstract

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.

Abstract

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.

Abstract

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.

Abstract

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.

Abstract

Ethylene, as an important chemical raw material, could be produced through the coal-based acetylene hydrogenation route. Nickel-based catalysts demonstrate significant activity in the semihydrogenation reaction of acetylene, but they encounter challenges related to catalyst deactivation and overhydrogenation. Herein, the effect of Sn promoter on Ni/CeO2 catalysts has been comprehensively explored for acetylene semihydrogenation. The optimized Ni/8%Sn-CeO2 catalytic performance was significantly improved, with 100% acetylene conversion and 82.5% ethylene selectivity at 250 degrees C, and the catalyst maintained high catalyst performance within a 1000 min stability test. A series of characterization tests show that CeO2 modified by moderate Sn4+ doping is more conducive to modulating the charge structure and geometry of the Ni active center. Additionally, the in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy and density functional theory results indicated that catalysts doped with Sn4+ facilitated more efficient desorption of ethylene from the catalyst surface compared to Ni/CeO2 catalysts, thus improving ethylene selectivity and yield. This study highlights an effective strategy for improving the catalytic performance of rare-earth-based catalysts through the incorporation of effective metal promoters.

Abstract

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.

Abstract

The direct conversion of carbon dioxide into hydrocarbons is a very desirable but difficult approach for achieving lower value-added olefins with minimal CO selectivity. In this effort, we report the direct conversion of CO2 into light olefins on a Cu/CeO2 hybrid catalyst mixed with SAPO-34 zeolite. The samples are characterized by N-2 sorption, XRD, TEM, SEM, NH3-TPD and H-2 -TPR. The results showed that the acidity of modified zeolite had decreased. The response surface methodology has been used to optimize the operating parameters (temperature and space velocity (SV)) of process. A high olefin selectivity of 70.4% has been obtained on CuCe/SAPO-34 at H-2/CO2 =3, 10 h, 382.46 degrees C, 17.33 L/g.h and 20 bar. The optimum operating conditions for multiple responses have also been achieved. The optimal values are T = 396.26 degrees C and SV = 5.80 L/g.h. Under these conditions, the predicted olefin and CO selectivity and CO2 conversion are 61.83%, 57.11% and 13.15%, respectively. Multiple optimization outputs are outstanding for obtaining the suitable operating conditions.

Abstract

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.

Abstract

In this study, the feasibility of preparing quinary equimolar high-entropy oxides within the Co–Cu–Fe–Mg–Mn–Ni–O system was explored using the reactive flash sintering (RFS) technique. Various compositions were tested using this technique under atmosphere pressure, leading to the formation of two primary phases: rock-salt and spinel. Conversely, a new high-entropy oxide was produced as a single-phase material with the composition (Co_0.2,Cu_0.2,Mg_0.2,Mn_0.2,Ni_0.2)O when RFS experiments were conducted in nitrogen atmosphere. The reducing conditions achieved in nitrogen enabled the incorporation of cations with oxidation states different from +2 into the rock-salt lattice, emphasizing the critical role of the processing atmosphere, whether inert or oxidizing, in the formation of high-entropy oxides. The electrical characterization of this material was obtained via impedance spectroscopy, exhibiting a homogeneous response attributed to electronic conduction with a temperature dependence characteristic of disordered systems. 

Abstract

Gel polymer electrolytes (GPEs) are regarded as a promising alternative to conventional electrolytes, combining the advantages of solid and liquid electrolytes. Leveraging the abundance and eco-friendliness of cellulose-based materials, GPEs were produced using methyl cellulose and incorporating various doping agents, either an ionic liquid (1-Butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide [Pyr14][TFSI]), its polymeric ionic liquid analogue (Poly(diallyldimethylammonium bis(trifluoromethylsulfonyl)imide) [PDADMA][TFSI]), or an anionically charged backbone polymeric ionic liquid (lithium poly[(4-styrenesulfonyl)(trifluoromethyl(S-trifluoromethylsulfonylimino) sulfonyl) imide] LiP[STFSI]). The ion dynamics and molecular interactions within the GPEs were thoroughly analyzed using Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR), Heteronuclear Overhauser Enhancement Spectroscopy (HOESY), and Pulsed-Field Gradient Nuclear Magnetic Resonance Diffusion (PFG-NMR). Li+ transference numbers (tLi+) were successfully calculated. Our study found that by combining slow-diffusing polymeric ionic liquids (PILs) with fast-diffusing lithium salt, we were able to achieve transference numbers comparable to those of liquid electrolytes, especially with the anionic PIL, LiP[STFSI]. This research highlights the influence of the polymer ' s nature on lithium-ion transport within GPEs. Additionally, micro supercapacitor (MSC) devices assembled with these GPEs exhibited capacitive behavior. These findings suggest that further optimization of GPE composition could significantly improve their performance, thereby positioning them for application in sustainable and efficient energy storage systems.

Abstract

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.

Abstract

This work shows the synthesis and characterization of the Zn2-xGeO4-GeO2:(x)Mn2+ (x = 0.10, 0.25, and 0.50 at.%) films using the Ultrasonic Spray Pyrolysis (USP) technique. These films were deposited at 500 degrees C and heat treated at 800 degrees C for 13 h. X-ray diffraction (XRD) measurements showed the rhombohedral and hexagonal phases of Zn2-xGeO4 (78.8 %) and GeO2 (21.2 %), respectively. SEM micrographs exhibited the surface morphology of these films. The STEM and HAADF show Ge, Zn, and O atomic layers. In addition, XPS was carried out to observe the oxidation states of Mn2+ (75.4 %) and Mn3+ (24.6 %) for the films doped with Mn ions (0.10 at.%). Incorporating manganese ions into the Zn2-xGeO4-GeO2 host lattice generated an extremely green emission, exciting at 250 nm. The photoluminescence and persistence luminescence properties were studied in accordance with the manganese doping concentration. For photoluminescence, it was found that the optimal doping percentage was 0.25 at.%, and for persistence luminescence, it was 0.10 at.% Mn with lambda(ex) = 250 nm. Quantum efficiency measurements gave a result of 100 %. In addition, preliminary CL measurements were exhibited.

Abstract

The effects of a remote oxygen plasma (ROP) treatment on the surface of commercial graphite felts were investigated and compared against a conventional thermal treatment. In contrast to methodologies where the sample is directly exposed to the plasma, ROP allows for a high control of sample-plasma interaction, thereby avoiding extensive etching processes on the fibre surface. To assess the impact of ROP treatment time, the electrodes were subjected to three different periods (10, 60, and 600 seconds). X-ray photoelectron spectroscopy showed that the ROP treatment introduced nearly three times more surface oxygen functionalities than the thermal treatment. Raman spectroscopy measurements revealed a significant increase in amorphous carbon domains for the ROP samples. The thermal treatment favoured increases in graphitic defects and resulted in an order of magnitude larger ECSA compared to the ROP treated materials despite having lower content in oxygen functionalities. The electrochemical analysis showed enhanced charge-transfer overpotentials for GF400. The ROP samples exhibited a lower mass-transport overpotential than the thermally treated material and had similar permeabilities, which overall translated to the thermal treatment offering better performance at fast flow rates. However, at slow flow rates (similar to 10 mL min-1), the ROP treatment for the shortest period offered comparable performance to conventional thermal treatment.

Remote oxygen plasma is compared to conventional thermal activation of electrodes for flow batteries and their impact on the mass transport and charge transfer properties of the resulting carbons.