This study presents an accessible and straightforward cyclic-thermogravimetric protocol that links the factors limiting CO2 capture by polymeric amines to the physicochemical properties of the matrices they impregnate. This protocol...

The development of functional composite materials is crucial for applications demanding the combination of complementary properties to achieve an enhanced performance. This study addresses a critical knowledge gap in the 3D characterization of polylactic acid (PLA) composites by investigating the relationship between zeolite modification and resulting film architecture. Zeolite-PLA films with ethylene-scavenging properties were prepared via solvent casting in chloroform without plasticizers. While films with pristine LTA zeolite displayed high surface roughness and microscale heterogeneity, the incorporation of Ag+/Zn2+-exchanged zeolites (AZN@LTA) induced a novel, cation-mediated vertical stratification. In these films, silver and zinc mobility -facilitated by the chloroform solvent acting as a mild reducing agent-promoted particle aggregation and sedimentation. This asymmetric architecture resulted in an exchanged zeolite-rich bottom layer and a PLA-rich upper layer, enhances ethylene adsorption and uptake capacity because it minimizes polymer encapsulation of the exchanged zeolite particles, preserving sites available for gas adsorption. Consequently, the AZN@LTA/PLA composite exhibited a remarkable monolayer ethylene adsorption capacity of 133.4 mu mol g- 1. Despite the high filler loading, the stratified films maintained thermal stability (Tonset approximate to 354 degrees C) and mechanical stiffness (Young's modulus approximate to 2159 MPa) comparable to neat PLA.

The effective and large-scale removal of cationic emerging contaminants requires low-cost materials possessing an inherent negative surface charge, thereby eliminating the need for expensive surface functionalization. To address this, Fe-silicalite zeolite was synthesized via a simple hydrothermal route using an industrial-grade poly(N-silicate) solution (Fe-SI) and compared with a counterpart obtained from analytical-grade sodium metasilicate (Fe-SA). Structural, morphological, and textural characterizations confirmed the formation of well-defined MFI frameworks with isomorphic Fe substitution. Notably, differences in the polymerization degree of the silicon sources led to distinct three-dimensional crystal architectures, promoting a more homogeneous iron distribution and generating a higher surface area with secondary intergranular porosity, potentially useful for transport properties. The adsorption performance was evaluated using metformin (MET) as a model cationic pharmaceutical contaminant. Both zeolites exhibited a negative surface charge over a wide pH range, driving electrostatic interactions with protonated MET. Equilibrium adsorption isotherms were well-described by the Langmuir model, confirming a high maximum capacity and a homogeneous monolayer distribution of MET onto the active zeolitic sites. Furthermore, the initial stage of adsorption kinetics was described by an intraparticle diffusion mechanism (Weber–Morris model), revealing that the hierarchical porosity of Fe-SI enhanced mass transport to deliver a rapid initial uptake. This superior kinetic behavior enabled Fe-SI to achieve a 97% removal efficiency within just 45 minutes, demonstrating that low-cost industrial precursors can yield highly efficient and sustainable adsorbents for water remediation.

Active packaging for reducing surrounding ethylene of climacteric produce is becoming more widespread in the global market. Their practical use requires shaping porous materials to confer mechanical strength, structural integrity, and improved handling properties. For this reason, powder materials and composites were studied to determine the evolution of the structure with the chemical composition and its influence on the adsorptive mechanisms. A zeolite NaA and an Ag+/Zn2+-exchanged A were synthesized to provide biocidal and ethylene-scavenging properties. The NaA and exchanged-A were shaped by moulding process using a matrix of poly (lactic acid) to produce a biocomposite leading to a composite with a porous structure in the macro scale with different interphases zeolite/polymer. The zeolite NaA was in close contact with the polymer while the formation of metal and oxide nanoparticles in exchanged-zeolite induced well-defined interphases evidencing a repulsive interaction between the polymer and the crystals.Powder materials exhibited the highest adsorption capacity. In NaA, physisorption was the primary adsorption mechanism, whereas in exchanged-A, chemisorption played a significant role. NaA is advantageous for recyclability due to the weak bonding of C2H4, allowing for easier regeneration. In contrast, exchanged zeolite demonstrated enhanced sensitivity for scavenging trace amounts of C2H4. The biocomposite containing exchanged-A displayed a distinct behavior, where chemisorption became the dominant adsorption mechanism.

Nowadays industrial requirements point to high-performance processes but cost-effective materials to maximize their benefit/cost balance. This paper describes the properties of a macro-mesoporous MCM-41 silica with very high surface area obtained from inexpensive reagents -industrial sodium silicate as a source of silicon and industrial CTAC as template- with potential use in an environmental application such as CO2 capture. The MCM-41 silica exhibits an aperiodic 3D hierarchical spatial organization at the macro-mesoscale, formed by well-ordered MCM-41 particles with bowl-like mesopores. These particles are interconnected in three dimensions, creating a web-like structure that imparts macroporosity. This organization can be rationalized in terms of the nature and interaction of the reactants. Thus, the conjunction of poly (N-silicate) and features in CTAC, such as the weakly bonding counterion (Cl-), ethanol and unreacted amine, gave rise to different morphologies and variable channel lengths, porosity at different length scales producing meso/macro arrangements, and a spongy structure as a disordered minority phase. The hierarchical organization enhances the potential of the material for uniform APTS loading, thereby improving CO2 capture. Then the use of industrial reactants offers two important advantages: (i) The presence of macro-mesocavities, enabling applications requiring greater porosity than that intrinsic to MCM-41; (ii) A reduction in production costs by at least 80 % compared to traditional synthesis methods using alkoxysilanes and CTAB, and negligible costs compared to synthesis with analytical grade CTAC. In summary, this study demonstrates the synthesis of a hierarchically structured MCM-41 silica using cost-effective industrial reagents, offering a promising and economical solution for different applications.

This paper explores the synthesis by the impregnation method using citric acid and the characterization of bimetallic Nickel-Cobalt (Ni-Co) catalysts, focusing on their application in ethanol steam reforming leveraging the demonstrated improved stability and catalytic activity observed in previous works when Co is introduced into Ni catalysts. The study aims to investigate the effects of the sequence of incorporation of Ni and Co in the catalyst support in order to optimize the catalytic performance. The results indicate that the optimal sequence for introducing Co and Ni significantly enhanced the catalytic performance in ethanol steam reforming and it was associated to a higher Ce+3/Ce+4 ratio and a stronger active site-support interactions that modified the CNT growth mechanism, preventing increasing pressure drop through the reactors. The best catalytic performance corresponded to the system, Co/Ni/MgAl2O4-CeO2, in which Co was incorporated after Ni.

La Fe-silicalita es una clase de zeolita en la que el catión Fe ocupa sitios con coordinación tetraédrica, sustituyendo isomórficamente al Si4+. Se ha propuesto que la actividad de este material estaría fuertemente relacionada con el Fe estructural y también con las especies de hierro que se generan luego del tratamiento térmico post-síntesis. Este material muestra actividad catalítica y también se ha utilizado en la eliminación de compuestos orgánicos en aguas contaminadas. Para esta última aplicación, el desafío se centra en obtener materiales económicos que mantengan una alta eficiencia en la remoción de contaminantes y sean fácilmente regenerables para su reutilización continua, garantizando así un tratamiento de agua sostenible y rentable. En este contexto, el objetivo de este trabajo fue obtener y caracterizar una Fe-silicalita de bajo costo para su uso en la remoción de fenoles en medio acuoso. El material obtenido se comparó con una Fe-silicalita tradicional, sintetizada a partir de un precursor de silicio de grado analítico. El material se obtuvo a través de un proceso hidrotermal, utilizando una solución de silicato de sodio industrial prepolimerizado como fuente de silicio. Luego se realizó un tratamiento térmico para la remoción del agente plantilla. Los difractogramas de Rayos X permitieron confirmar que el material sintetizado corresponde a una estructura MFI.El Fe en la estructura se corroboró por la presencia de la banda correspondiente a los enlaces Fe-Si-O en el espectro de FT-IR. Las imágenes de HRTEM mostraron cristales de hábito prismático. El área BET evidenció un valor de 356,41 m²/g. Esta zeolita de producción económica demostró una capacidad superior para la remoción de fenoles en medio acuoso. Esto evidencia un doble beneficio: es un material de bajo costo y además podría ser más efectivo para la remoción de compuestos orgánicos contaminantes.

Metal nanostructures have received significant attention in recent years owing to their peculiar physical and chemical properties, which span a wide range of practical applications in a variety of scientific and engineering fields. Herein, we report a study of the optical properties and application in the field enhancement of silver nanoplates (Ag-Nplates) obtained by two-step chemical synthesis. Optical Extinction Spectroscopy (OES), together with a detailed theoretical analysis of the experimental spectra, was used to characterize the size distribution, morphology, and optical spectral behavior of the obtained suspensions. These studies were complemented with shape and size distribution analyses using Transmission Electron Microscopy (TEM). It was observed by both techniques that these characteristics are related to the concentration of silver spherical nanoparticles (Ag-Seeds) added during the synthesis of Ag-Nplates. A decrease in the Ag-Seed amount produces an infrared shift of the main plasmon peak with respect to the neat Ag-Seeds suspension, which is related to the size growth of Ag-Nplates showing size distributions centered in the edge length range of 12-15 nm and 34-36 nm for the experimental spectra, whose plasmon peak positions are at 543 nm (higher Ag-Seeds concentration) and 815 nm (lower Ag-Seed concentration), respectively. The detection of Brilliant Blue (BB) by Surface-Enhanced Raman Spectroscopy (SERS) was successfully probed with the incorporation of Ag-Nplates in an agarose gel.

The cathodic material LiNi0.5Mn1.5O4 was produced by the Solution Combustion Synthesis method (SCS). The as-made crystalline nanoparticles were annealed at 900 degrees C, obtaining micron-sized particles, and then coated with ZnO nanocrystals at a weight relation between 0.5 and 2.5 wt%, also using the SCS method. The nanocrystalline porous coating was confirmed by XRD, SEM and TEM. Electrochemical measurements verified that all materials coated with ZnO nanoparticles improved their electrochemical properties concerning the uncoated material, preventing degradation over the cycles, and stability along cyclic voltammetry cycles. It was observed that a 1 wt% ZnO coating presents the best improvement in discharge capacity and rate capability, and that the charge transfer resistance of the coated material is reduced to 1/3 of the uncoated one after 100 electrochemical cycles. In this work, the simple, time and energy saving SCS method was verified to obtain nanoshell-coated LNMO microparticles with improved electrochemical performance.

The synergy of superparamagnetic iron oxide nanoparticles (SPIONs) and ionizing radiation (IR), attributed to reactive oxygen species (ROS) and DNA double-strand breaks (DSBs) increase, was widely investigated in different cancers, but scarcely in melanoma. Herein, SPIONs were evaluated as radiosensitizers in A-375 human melanoma cells. Moreover, the effect of the combined treatment of SPIONs and gamma irradiation (SPIONs-IR) was assessed at the DNA level, where DSBs induction and their repair capacity were studied. SPIONs were synthesized, stabilized by poly(ethylene glycol) methyl ether and physicochemically characterized by high resolution-transmission electron microscopy (HR-TEM), X-ray diffraction and magnetometry and dynamic light scattering. The obtained nanoparticles showing superparamagnetic behavior and low dispersion in shape and sizes were tested in A-375 cells. The intracellular internalization of SPIONs was verified by HR-TEM and quantified by inductively coupled plasma atomic emission spectroscopy. Cells treated with SPIONs exhibited high ROS levels without associated cytotoxicity. Next, a significant radiosensitization in SPIONs-IR vs. control (IR) cells was demonstrated at 1 Gy of gamma radiation. Furthermore, a decreased DSBs repair capacity in SPIONs-IR vs. IR-treated cells was evidenced by the size increase of persistent phosphorylated H2AX foci at 24 h post-irradiation. In conclusion, these nanoparticles show the potential to radiosensitize melanoma cells by the induction of unrepairable DNA damage.

Different kinds of highly porous nanostructured carbon (xerogels) were obtained by a new synthetic strategy based on surface-driven polymerization of resorcinol–formaldehyde resin in the presence of zinc oxide (ZnO) nanostructures. The synthesis method involved spatially confined polycondensation of resorcinol with formaldehyde in the presence of ZnO nanostructures, which act as a scaffold as well as a catalyst assisted by ultraviolet (UV) light irradiation. Using this method, two different carbon-based nanomaterials composed of ZnO nanostructures coated with carbon were prepared. The regulation of synthesis parameters, including monomer concentration and UV exposition time, leads to the synthesis of different porous materials, as was evidenced by scanning electron microscopy and transmission electron microscopy images. Electrochemical characterization of the prepared materials showed specific capacities up to 140 F g−1, as well as high charge/discharge rate. Once an electrode is integrated in an experimental capacitor, the material exhibits an electrochemical operative window up to 1.8 V in aqueous media, with a specific energy density of 23 Wh/kg and a power density of 7.3 × 103 W/kg of active material. Schematic representation of light-assisted synthesis of carbon nanomaterials using ZnO structures as catalysts/template, showing the principal stages of the process

We propose here a novel green synthesis route of core-shell magnetic nanomaterials based on the polyol method, which uses bio-based substances (BBS) derived from biowaste, as stabilizer and directing agent. First, we studied the effect of BBS concentration on the size, morphology, and composition of magnetic iron oxides nanoparticles obtained in the presence of BBS via the polyol synthesis method (MBBS). Then, as a proof of concept, we further coated MBBS with mesoporous silica (MBBS@mSiO(2)) or titanium dioxide (MBBS@TiO2) to obtain magnetic nanostructured core-shell materials. All the materials were deeply characterized with diverse physicochemical techniques. Results showed that both the size of the nanocrystals and their aggregation strongly depend on the BBS concentration used in the synthesis: the higher the concentration of BBS, the smaller the sizes of the iron oxide nanoparticles. On the other hand, the as-prepared magnetic core-shell nanomaterials were applied with good performance in different systems. In particular, MBBS@SiO2 showed to be an excellent nanocarrier of ibuprofen and successful adsorbent of methylene blue (MB) from aqueous solution. MBBS@TiO2 was capable of degrading MB with the same efficiency of pristine TiO2. These excellent results encourage the use of bio-based substances in different types of synthesis methods since they could reduce the fabrication costs and the environmental impact.

We explore the use of industrial sources of silicon and surfactant for obtaining low-cost MCM-41 materials and evaluate their performances as CO2 adsorbents. All of them presented a high specific surface area with different structural characteristics and textural properties. Interestingly, the MCM-41 manufactured with the most economical reagents presented a SBET of 1602 m2·g−1. The template was removed by using thermal treatments in an air atmosphere or a washing process. Preservation of silanol groups proved to be more effective under washing or mild thermal treatment conditions with the advantage of their lower cost and environmental benefit. Surface reactivity against CO2 was enhanced by anchoring APTS to silanol groups through wet grafting. All amino-functionalized materials showed a performance as CO2 adsorbents comparable to those reported in the literature, reaching values close to 30 cm3·g−1 at 25 °C and 760 mmHg. Samples with a higher concentration of silanol groups showed better performance. Our studies indicate that adsorbed CO2 is retained at least up to 50 °C, and the CO2 is chemisorbed on the silica modified with amine groups. The chemisorbed gas at very low pressures points to the potential use of these materials for CO2 storage.

Materials with nanosized dimensions exhibit different and interesting properties compared with their bulk counterpart, which is broadly applicable in several fields, including Li-ion batteries. These properties are intimately related to the morphological, compositional, and topographic features of the nanostructures, which are strongly dependent on the methods used to synthesize nanoparticles. Herein we present the synthesis of LiMn2O4 nanoparticles with controlled morphology by a thermal decomposition method of organometallic precursors followed by thermal treatment in air. The crystal structure, chemical composition, and morphology of the samples were analyzed by X-ray diffraction, transmission electron microscopy, electron diffraction, and electron energy-loss spectroscopy. By adjusting the reflux temperature and atmosphere we obtained nanoparticles and hollow nanostructures, while core-shell LiMn2O4/Li2O nanoparticles were obtained by adding a thermal decomposition stage.

Dipolar and RKKY interactions, tuned by intercluster separation, play a significant role in the magnetic behaviour of PEDOT:DBS–Fe 3 O 4 composites.

Ni–Co catalysts supported on MgAl2O4–CeO2 were prepared by the sol–gel method. The solids were calcined under a reducing atmosphere to obtain Ni and/or Co active sites. The influence of the cobalt content (1, 3 and 5% w/w) was studied on bimetallic catalysts containing 8% w/w of Ni. The catalysts were characterized by TG, FTIR, SBET, AAS, XRD, TPR, TEM, EELS, EFTEM, TPO and SEM. XRD patterns of the reduced samples did not reveal the presence of Ni nor Co, nor the possible formation of a metallic alloy, which suggests that metallic crystallite sizes are smaller than the detection limit of the technique (5 nm). The catalysts were evaluated in the ethanol steam reforming reaction at 650 °C for 7 h. The results showed that the catalytic activity and the H2 selectivity are favored in bimetallic catalysts. The main reaction products were H2, CO2, CO and, to a lesser amount, CH4, being the hydrogen selectivity being greater than 80%. The best behavior in terms of the activity, stability and tolerance to carbon deposition was observed in Co3Ni/MC system. These results suggest the existence of an optimal Co/Ni ratio in the sample whit 3 wt% Co and 8 wt% Ni.

Two different synthesis approaches were used to prepare silver/iron oxides nanocomposites: the polyol synthesis and laser ablation. The nanocomposites consisted of 10–20 nm Ag nanoparticles immersed in 100––300 nm iron oxide structures, being the Ag:Fe greater for the nanomaterial prepared by the chemical procedure. Both nanomaterials were able to catalyze the NaBH4-mediated reduction of the model contaminant 3-nitrophenol (3-NP). Photoirradiation had no effect on the performance of the nanocomposite prepared by laser ablation, whereas it produced a drastic improvement of the catalytic effect of the nanomaterial prepared by polyol synthesis, a result related to the silver content of the nanomaterials. A heterogeneous photocatalytic mechanism is proposed.

Crystalline LiCoO2 nanoparticles were coated with NiO nanocrystals. The coating was made using a one-pot strategy by solution combustion synthesis with different weight percentages. The method used is simple, economical, and easily scalable. The resulting materials were characterized morphologically, structurally, and electrochemically by transmission and scanning electron microscopy, charge/discharge cycles, rate capability, voltammetry, and electrochemical impedance spectroscopy techniques. The results showed that a uniform coating with crystalline NiO nanoparticles on the LiCoO2 was obtained. For optimal coating, the discharge capacity reached 74% retention after 100 cycles between 3.0 and 4.5V at 0.1C, while the uncoated material retained only 5% of its initial capacity. Thus, the introduced NiO coating protects the LiCoO2 electrode against the unwanted reactions that occur in contact with the electrolyte at high voltage. Therefore, the irreversible loss of the active material capacity will be minimized.

Lithium oxosilicate has the highest proportion of lithium among lithium silicates, which is desirable for applications. Although Li8SiO6 is a stable phase, its obtention as a polycrystalline pure phase is not reported yet, probably because of the high sensitivity of the system Li2O–SiO2 to the synthesis conditions. In this work, we adapted a citrate-based route used for the synthesis of Li4SiO4 as a novel approach to the obtention of Li8SiO6. We found that the lowest amount of impurities is achieved by using a Li:C6H8O7 molar ratio of 2.8:1, a pH value of 8.5, and a lithium excess of 20%. In a complementary way, we used the solid-state reaction method as a function of the excess of lithium and optimized the conditions that lead to a minimum amount of impurities. We found that the purest Li8SiO6 phase is obtained with low or no lithium excess. Samples obtained by both methods exhibited a higher purity compared to the reports available in literature. The crystal structure for this phase is confirmed by selected area electron diffraction.

Co catalysts supported on La2O3-SiO2 binary systems were used in the steam ethanol reforming reaction for the production of hydrogen. Calcined and used catalysts were characterized by different techniques, in situ Raman spectroscopy, XPS and HRTEM to determine the Co species present in the solids before and after the reaction. The Co catalysts were active and stable for H-2 production. In order to improve catalyst stability and H-2 production, the contact time (W/F) effect was studied (4.9 10(-3) g h L-1 to 3.3 10(-2) g h L-1). In the case of the catalytic measurements with lower W/F, the catalyst with 15 wt% of Co presented higher selectivity to H-2. It was observed that a higher content of Co-0 species increased the hydrogen yield, suggesting that metallic cobalt could be the active species in most of the parallel reactions that occur in the reforming of ethanol. In the solid with lower Co content, the low formation of carbon nanotubes produced a slight decrease of ethanol conversion with a decrease in the hydrogen yield. On the other hand, in the catalyst with higher cobalt content the carbonaceous deposits are of the amorphous type and the hydrogen yield equal to 3.5 remained constant with time on stream. The most active and stable catalyst with 15 wt% of Co was tested in a membrane reactor, obtaining a high H-2 recovery of 54% under moderate reaction conditions (H2O/ethanol = 5, 500 degrees C and 1 bar).