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Li-ion batteries (LIBs) are used in several applications, such as portable electronics and electric vehicles, owing to their high energy density, and longer cycle life. LIB's functionality and reliability are intensely improved by the binder materials used in the electrode assembling development. Classically polymeric compounds and binder materials are essential for electrode construction as they interlock active materials and conductive additives, granting mechanical stability and electron/ion transport pathways. Binder migration has numerous hostile impacts, incorporating diminished electrode stability, intensified internal resistance, defeat of active material exploitation, and prospective short-circuiting, which result in capacity weakening, declined cycle life, and compromised safety. Thus, the design of electrodes plays a crucial role in the performance of commercial rechargeable batteries, as their properties significantly impact battery cell performance. This review summarizes the reported phenomena of binder migration in both anode and cathode materials and discusses some of the attempted solutions to overcome or alleviate this issue. Some of the approaches that were taken to alleviate the binder migration issue as well as limitations of each approach are summarized. Finally, future perspectives are further presented to fully address the binder migration issue.

In this work, a detailed comprehensive investigation explores the impact of processing methods and chemical activation parameters on the textural properties of a series of activated carbons (ACs) derived from Argan Nut Shell (ANS) residue using KOH. This study aims to develop and optimize high-quality ACs for use as solid-state supercapacitors with superior performance in a 1 M H2SO4 electrolyte. The two-step process (involving ANS carbonization followed by activation) is found to significantly enhance specific surface area and total pore volume compared to a one-step process, reaching values of 2334 m2·g−1 and 1.21 cm3·g−1 versus 1394 m2·g−1 and 0.83 cm3·g−1, respectively. The superior surface area and pore volume results are achieved at a KOH/char mass ratio of 4:1, carbonization temperature of 500 °C, and an activation temperature of 800 °C, reaching 3091 m2·g−1 and 1.52 m3·g−1, respectively. Evaluation of electrochemical properties in a two-electrode system with 1 M H2SO4 electrolyte demonstrates outstanding capacitance and maximum specific energy at a current density of 125 mA·g−1, reaching up to 416 F·g−1 and 14.5 Wh·kg−1 at a specific power of ~120 Wkg−1. This superior performance is attributed to the ACs' high surface area, well-developed microporosity, and favorable surface chemistry. Additionally, the ACs demonstrate exceptional cycling stability, as they retain 99 % of their specific capacitance even after undergoing 2500 charge and discharge cycles at a rate of 1 A·g−1. This work offers a novel strategy for reclaiming Argan Nutshell, offering a sustainable approach for electrode materials in solid-state supercapacitors.

BaMnO3 (BM) and Ba0.9A0.1MnO3 (BM-A) (A = Ce, La or Mg) perovskite-type mixed oxides were synthesized by the aqueous sol–gel method; thoroughly characterized by ICP-OES, XRD, H2-TPR, BET, and O2-TPD; and tested as catalysts for CO oxidation under simulated automobile exhaust conditions. The characterization results indicate that the main effects of the partial substitution of Ba with A-metal in BM perovskite are the maintenance of the hexagonal structure of the perovskite and the increase in reducibility and oxygen mobility. All samples catalyze the CO to CO2 oxidation reaction in the different reactant mixtures employed, showing the best performance for the mixture with the lowest CO/O2 ratio and in the presence of a dopant in the BM perovskite formulation. BM-La is the most active catalyst for improving CO oxidation, as it is the most reducible, and because is able to evolve oxygen at intermediate temperatures.

This study explores the effects of liquid-phase and gas-phase oxidation treatments on a low-ash activated carbon (RGC30) and its subsequent use as a metal-free catalyst for the hydrogenation of 1-chloro-4-nitrobenzene. Characterisation of the catalysts was accomplished through N2 and CO2 adsorption at −196 °C and 0 °C, respectively, together with techniques like X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, thermogravimetric analysis (TGA) and temperature-programmed desorption (TPD). In particular, it is observed that the catalytic activity depends on the specific oxidation treatment applied, which leads to the generation of different oxygenated groups on the carbon surface. Consequently, through precise control of oxygen groups via thermal treatment under inert conditions, it is found that the most influential groups for the hydrogenation of 1-chloro-4-nitrobenzene are basic groups incorporating Cdouble bondO bonds, such as quinones and carbonyls. Furthermore, certain groups, like phenols, exhibit a detrimental impact on the catalytic activity.

The sol–gel method, adapted to aqueous media, was used for the synthesis of BaMn0.7Cu0.3O3 (BMC) and Ba0.9A0.1Mn0.7Cu0.3O3 (BMC-A, A = Ce, La or Mg) perovskite-type mixed oxides. These samples were fully characterized by ICP-OES, XRD, XPS, H2-TPR, BET, and O2–TPD and, subsequently, they were evaluated as catalysts for CO oxidation under different conditions simulating that found in cars exhaust. The characterization results show that after the partial replacement of Ba by A metal in BMC perovskite: (i) a fraction of the polytype structure was converted to the hexagonal BaMnO3 perovskite structure, (ii) A metal used as dopant was incorporated into the lattice of the perovskite, (iii) oxygen vacancies existed on the surface of samples, and iv) Mn(IV) and Mn(III) coexisted on the surface and in the bulk, with Mn(IV) being the main oxidation state on the surface. In the three reactant atmospheres used, all samples catalysed the CO to CO2 oxidation reaction, showing better performances after the addition of A metal and for reactant mixtures with low CO/O2 ratios. BMC-Ce was the most active catalyst because it combined the highest reducibility and oxygen mobility, the presence of copper and of oxygen vacancies on the surface, the contribution of the Ce(IV)/Ce(III) redox pair, and a high proportion of surface and bulk Mn(IV). At 200 °C and in the 0.1% CO + 10% O2 reactant gas mixture, the CO conversion using BMC-Ce was very similar to the achieved with a 1% Pt/Al2O3 (Pt-Al) reference catalyst.

To enhance their corrosion protection, Guefoams were coated with RGO using both potentiostatic and potentiodynamic methods. The potentiodynamic method produced the thickest RGO coating and the lowest Cl, O, and Al content, as observed using FESEM and EDX. The Guefoams were exposed to a 3.5% NaCl solution and steam. The polarization resistance was examined, electrochemical impedance spectroscopy was performed, and polarization curves were constructed to monitor the corrosion process. After 28 days, the Al concentrations in the solutions were measured, and were found to be 145 mg/L (bare Guefoam), 70 mg/L (RGO-coated, potentiostatic), and 35 mg/L (RGO-coated, potentiodynamic). The potentiodynamic RGO coating also showed the best corrosion protection values.

The present review revisits representative studies addressing the development of efficient Pd-based carbon-supported heterogeneous catalysts for two important reactions, namely, the production of hydrogen from formic acid and the hydrogenation of carbon dioxide into formic acid. The HCOOH-CO2 system is considered a promising couple for a hydrogen storage system involving an ideal carbon-neutral cycle. Significant advancements have been achieved in the catalysts designed to catalyze the dehydrogenation of formic acid under mild reaction conditions, while much effort is still needed to catalyze the challenging CO2 hydrogenation reaction. The design of Pd-based carbon-supported heterogeneous catalysts for these reactions encompasses both the modulation of the properties of the active phase (particle size, composition, and electronic properties) and the modification of the supports by means of the incorporation of nitrogen functional groups. These approaches are herein summarized to provide a compilation of the strategies followed in recent studies and to set the basis for a hydrogen storage system attained using the HCOOH-CO2 couple.

The present work delves into the feasibility of employing a novel structured sorbent referred to as GFAD (Guefoam Adsorption Device) for the determination of volatile organic compounds (VOCs) in liquid samples. The chosen method has been static headspace sorptive extraction-thermal desorption gas chromatography mass spectrometry (HSSE-TD-GC–MS). The GFAD comprises an aluminum cellular material with a distinct replication structure and a solid guest phase consisting of activated carbon particles dispersed within the cavities of the cellular aluminum. The extensive specific surface area, robustness, and exceptional thermal conductivity of this pioneering material offer distinct advantages over commercially available polydimethylsiloxane-based Twister® devices. Therefore, the trapping efficiency for volatile organic compounds is enhanced, and it is possible to perform the analysis of concentrated samples. According to computational simulations, it has been demonstrated that GFAD has a high heat conductivity. As a result, the desorption efficiency is improved, and minimal temperature gradients are generated throughout the GFAD during the heating process. Besides, the energy consumption is significantly lowered, thus aligning with environmentally conscientious and sustainable analytical practices. The experimental results give a proof of the suitability of the GFAD for determining gaseous compounds in liquid samples through HSSE-TD-GC–MS. For volatile species, the new material provides higher peak areas and lower limits of detection than a commercially available Twister® device. Furthermore, the GFAD is reusable, its adsorbing properties remaining unchanged during, at least, 100 consecutive analyses. In addition, unlike to the Twister®, no intense siloxane peaks are observed in the chromatograms obtained with the GFAD. The feasibility of qualitative and semi-quantitative analysis with the new accessory has been demonstrated with both standards and a cereal bioethanol rea

In the present work, multifunctional electrocatalysts formed by palladium nanoparticles (Pd NPs) loaded on Fe or Cu-containing composite supports, based on carbon nitride (C3N4) and super-activated carbon with a high porosity development (SBET 3180 m2/g, VDR 1.57 cm3/g, and VT 1.65 cm3/g), were synthesised. The presence of Fe or Cu sites favoured the formation of Pd NPs with small average particle size and a very narrow size distribution, which agreed with Density Functional Theory (DFT) calculations showing that the interaction of Pd clusters with C3N4 flakes is weaker than with Cu- or Fe-C3N4 sites. The electroactivity was also dependent on the composition and, as suggested by preliminary DFT calculations, the Pd-Cu catalyst showed lower overpotential for hydrogen evolution reaction (HER) while bifunctional oxygen reduction reaction/ oxygen evolution reaction (ORR/OER) behaviour was superior in Pd-Fe sample. The Pd-Fe electrocatalyst was studied in a zinc-air battery (ZAB) for 10 h, showing a performance similar to a commercial Pt/C + RuO2 catalyst with a high content of precious metal. This study demonstrates the synergistic effect between Pd species and transition metals and shows that transition metals anchored on C3N4-based composite materials promote the electroactivity of Pd NPs in HER, ORR and OER due to the interaction between both species.

3D-printed high-surface carbon monoliths have been fabricated and tested as catalyst supports of CO2 metha nation active phases (NiO-CeO2, 12 wt% Ni). The carbon carriers show a developed microporosity and good adherence to the catalytic phases of NiO-CeO2, showing great stability and cyclability. Two monolith designs were used: a conventional parallel-channeled structure (honeycomb) and a complex 3D network of non-linear channels built upon interconnected circular sections (circles), where flow turbulences along the reactant gas path are spurred. The effect of the active phases particle size on the catalyst distribution and the overall per formance has been assessed by comparing NiO-CeO2 nanoparticles of 7 nm verage (Np), with a reference counterpart of uncontrolled structure (Ref). The improved radial gases diffusion in the circles monolith design is confirmed, and nanoparticles show enhanced CO2 methanation activity than the uncontrolled-size active phase at low temperatures (< 300 ºC). On the contrary, the Ref catalysts achieve higher CH4 production at higher temperatures, where the reaction kinetics is controlled by mass transfer limitations (T > 300 ºC). SEM and Hg porosimetry evidence that nanoparticles are deposited at deeper penetration through the narrow micropores of the carbon matrix of the monolithic supports, which tend to accumulate on the channels surface remaining more accessible to the reactant molecules. Altogether, this study examines the impact of the channel tortuosity and the active phase sizing on the CO2 methanation activity, serving as ground knowledge for the further rational and scalable fabrication of carbon monolith for catalytic applications.

Metal–organic frameworks have drawn attention as potential catalysts owing to their unique tunable surface chemistry and accessibility. However, their application in thermal catalysis has been limited because of their instability under harsh temperatures and pressures, such as the hydrogenation of CO2 to methanol. Herein, we use a controlled two-step method to synthesize finely dispersed Cu on a zeolitic imidazolate framework-8 (ZIF-8). This catalyst suffers a series of transformations during the CO2 hydrogenation to methanol, leading to ~14 nm Cu nanoparticles encapsulated on the Zn-based MOF that are highly active (2-fold higher methanol productivity than the commercial Cu–Zn–Al catalyst), very selective (>90%), and remarkably stable for over 150 h. In situ spectroscopy, density functional theory calculations, and kinetic results reveal the preferential adsorption sites, the preferential reaction pathways, and the reverse water gas shift reaction suppression over this catalyst. The developed material is robust, easy to synthesize, and active for CO2 utilization.

Graphene oxide (GO) has been electrochemically synthesized by chronoamperometry and using a three-electrode system. Iron, manganese and cobalt phthalocyanines (FePc, MnPc and CoPc, respectively) have been incorporated to GO. These materials were characterized both physicochemically (X-ray Photoelectron Spectroscopy (XPS), UV–Vis, elemental analysis and Raman spectroscopy), morphologically (Transmission Electron Microscopy, TEM) and electrochemically (cyclic voltammetry). Electrochemical studies included the oxygen reduction reaction (ORR) and Zn-air battery performance using the synthesized electrocatalysts. In addition, graphene oxide buckypapers (GOBs) have been fabricated and evaluated as self-supporting electrodes for the Zn-air battery. Both GO/FePc and FePc supported on GOB (GOB/FePc), with a Fe content lower than 0.5 wt%, were subjected to Zn-air battery discharging tests. Both GO/FePc and GOB/FePc show comparable performance to the commercial Pt-based electrocatalyst using a much lower amount of metal.

Chemistry plays a central role in science and is the basis of one of the major, more impactful, and diverse industries. However, to address the most pressing global challenges, we must learn to create connections in an effective and meaningful way, with other disciplines, industries, and society at large. Here, we present the IUPAC Top Ten Emerging Technologies in Chemistry as an example of an initiative that highlights some of the most promising advances in chemistry and contributes to creating connections to accelerate sustainable solutions for our society and our planet.

Multilayer graphene (MLG), obtained by mild sonication of graphite in NMP, was functionalised via 1,3-dipolar cycloaddition with azomethine ylides generated by thermal 1,2-prototropy from various imino esters. The microwave-assisted functionalisation took place in five hours at 100 °C. The resulting MLG, containing substituted proline-based amine functional groups, was characterized using XPS and showed a nitrogen loading three times that obtained for the same transformation performed for five days using convection-assisted heating. The preparation of the imino ester containing a bipyridine unit at the arylidene position allowed for the preparation of the corresponding functionalised MLG, which incorporated the ruthenium atom to achieve a heterogeneous MLG-Ru complex. This supported complex was tested, as a proof of concept, as a photocatalyst of the aerobic oxidative hydroxylation of 4-methoxyphenylboronic acid.

The literature rarely compiles studies devoted to removing pollutants in aqueous media comparing adsorption versus photocatalytic degradation and does not pay enough attention to the analysis of combined adsorption-photocatalytic oxidation processes. In the present manuscript, the removal of malachite green (MG) from aqueous solutions has been investigated in three different cheap and sustainable scenarios: i) adsorption on activated carbon (AC) derived from a residue, luffa cylindrica, ii) photocatalytic oxidation under simulated solar light using titanium dioxide (TP) and iii) combined adsorption-photocatalytic oxidation using TP-AC (70/30 wt/wt.) under simulated solar light. The study has revealed that in the three scenarios and studied conditions, the total removal of this endocrine-disrupting dye from the solution takes place in the assayed time, 2 h, although in some cases just in a few minutes. MG adsorption on the AC is the fastest removal method. MG photocatalytic oxidation with TP also occurs efficiently, although the oxidized MG is not totally mineralized. MG removal using the TP-AC composite under simulated solar light occurs at a rate comparable to that of the MG adsorption on AC, since adsorption is the dominating removal mechanism, more than 90% of the removed MG with TP-AC under simulated solar light is adsorbed in this carbon-containing composite. The obtained results highlight the interest in adsorption, being the selection of the most suitable removal method dependent on several factors (i.e., cost of the AC regeneration, if adsorption, or the toxicity of the intermediate oxidation species, if photooxidation). Paying attention to MG photooxidation with TiO2, comparison of two working photodegradation schemes shows that the direct photodegradation of MG from solution, avoiding any initial dark equilibrium period, is the more efficient option from a time perspective. The use of scavengers has proved that MG photodegradation occurs via an oxidation m

The tandem CO2 hydrogenation to hydrocarbons over mixed metal oxide/zeolite catalysts (OXZEO) is an efficient way of producing value-added hydrocarbons (platform chemicals and fuels) directly from CO2 via methanol intermediate in a single reactor. In this contribution, two MAPO-18 zeotypes (M = Mg, Si) were tested and their performance was compared under methanol-to-olefins (MTO) conditions (350 °C, PCH3OH = 0.04 bar, 6.5 gCH3OH h–1 g–1), methanol/CO/H2 cofeed conditions (350 °C, PCH3OH/PCO/PH2 = 1:7.3:21.7 bar, 2.5 gCH3OH h–1 g–1), and tandem CO2 hydrogenation-to-olefin conditions (350 °C, PCO2/PH2 = 7.5:22.5 bar, 1.4–12.0 gMAPO-18 h molCO2–1). In the latter case, the zeotypes were mixed with a fixed amount of ZnO:ZrO2 catalyst, well-known for the conversion of CO2/H2 to methanol. Focus was set on the methanol conversion activity, product selectivity, and performance stability with time-on-stream. In situ and ex situ Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), solid-state nuclear magnetic resonance (NMR), sorption experiments, and ab initio molecular dynamics (AIMD) calculations were performed to correlate material performance with material characteristics. The catalytic tests demonstrated the better performance of MgAPO-18 versus SAPO-18 at MTO conditions, the much superior performance of MgAPO-18 under methanol/CO/H2 cofeeds, and yet the increasingly similar performance of the two materials under tandem conditions upon increasing the zeotype-to-oxide ratio in the tandem catalyst bed. In situ FT-IR measurements coupled with AIMD calculations revealed differences in the MTO initiation mechanism between the two materials. SAPO-18 promoted initial CO2 formation, indicative of a formaldehyde-based decarboxylation mechanism, while CO and ketene were the main constituents of the initiation pool in MgAPO-18, suggesting a decarbonylation mechanism. Under tandem CO2 hydrogenation conditions, the presence of high water concentrations and low me

Science, including mathematics, physics, and, of course, chemistry, has its own language and symbols and names we learn in school. However, to teach it, communicate it, and use it, we use our own native languages. Most of the scientific literature, including this article, is in English, as are the texts published by the various scientific unions, including the International Union of Pure and Applied Chemistry (IUPAC), to define scientific nomenclature, terminology, and presentation. However, it is essential that these fundamental texts are available in as many languages as possible to facilitate their teaching, learning, and use throughout the world. It should be noted, however, that the translation of these texts into different languages is a complex task that requires some choices due to the lack of obvious alternatives or the cacophony of some terms. In this paper, we provide some details on the challenges, compromises, and difficult decisions involved in translating the IUPAC Nomenclature Brief Guides into Spanish.

This study evaluates the removal of several dyes with different charge properties, i.e., anionic (Acid Red 88), cationic (Basic Red 13), and neutral (Basic Red 5) using transition metal-doped TiO2 supported on a high-surface-area activated carbon. Experimental results confirm the successful deposition of TiO2 and the derivatives (Zr-, Cu-, and Ce-doped samples) on the surface of the activated carbon material and the development of extended heterojunctions with improved electronic properties. Incorporating a small percentage of dopants significantly improves the adsorption properties of the composites towards the three dyes evaluated, preferentially for sample AC/TiO2_Zr. Similarly, the photodegradation efficiency highly depends on the nature of the composite evaluated and the characteristics of the dye. Sample AC/TiO2_Zr demonstrates the best overall removal efficiency for Acid Red 88 and Basic Red 5—83% and 63%, respectively. This promising performance must simultaneously be attributed to a dual mechanism, i.e., adsorption and photodegradation. Notably, the AC/TiO2_Ce outperformed the other catalysts in eliminating Basic Red 13 (74%/6 h). A possible Acid Red 88 degradation mechanism using AC/TiO2_Zr was proposed. This study shows that the removal efficiency of AC/TiO2 composites strongly depends on both the material and pollutant.

Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are key electrochemical reactions for the development of rechargeable Zn-air batteries. However, due to the high cost of commercial noble metal-based catalysts and their limited bifunctionality, it is necessary the design of new electrocatalysts. In this study, stable electrocatalysts have been synthesized through a hydrothermal method and further low-temperature thermal treatment. The materials consist of La stabilized low crystallinity Mn and Co metal (hydro-)oxides. The electrocatalytic performance of these materials has been compared with counterparts calcined at higher temperatures. The findings demonstrate that materials synthesized at lower temperatures and with low crystallinity exhibit superior electrocatalytic activity for both ORR and OER. Moreover, the research highlights the favorable influence of the lanthanum cation, which enhances changes of surface morphology and oxidation states of other cations (Mn and Co). Additionally, the positive contribution of the carbon component to electrochemical activity and electrical conductivity has been elucidated. The best electrocatalyst was studied in a rechargeable Zn-air battery with a durability of up to 120 hours. They exhibited better stability and performance than the commercial Pt/C + RuO2 catalyst currently used.

Hydrogen storage by cryoadsorption on porous materials has the advantages of low material cost, safety, fast kinetics, and high cyclic stability. The further development of this technology requires reliable data on the H2 uptake of the adsorbents, however, even for activated carbons the values between different laboratories show sometimes large discrepancies. So far no reference material for hydrogen cryoadsorption is available. The metal-organic framework ZIF-8 is an ideal material possessing high thermal, chemical, and mechanical stability that reduces degradation during handling and activation. Here, we distributed ZIF-8 pellets synthesized by extrusion to 9 laboratories equipped with 15 different experimental setups including gravimetric and volumetric analyzers. The gravimetric H2 uptake of the pellets was measured at 77 K and up to 100 bar showing a high reproducibility between the different laboratories, with a small relative standard deviation of 3–4 % between pressures of 10–100 bar. The effect of operating variables like the amount of sample or analysis temperature was evaluated, remarking the calibration of devices and other correction procedures as the most significant deviation sources. Overall, the reproducible hydrogen cryoadsorption measurements indicate the robustness of the ZIF-8 pellets, which we want to propose as a reference material.

Uno de los principales retos sociales actuales es la reducción de las emisiones de CO2 a la atmósfera, derivadas de la quema de combustibles fósiles utilizados principalmente en centrales térmicas para producir energía. Las energías renovables han surgido como una alternativa limpia y viable para disminuir los gases de efecto invernadero y las emisiones de CO2, aunque su intermitencia es un obstáculo importante para su aplicación universal. La energía solar concentrada (CSP en inglés) mediante tecnología de torre consiste en la concentración de la radiación solar lo que permite alcanzar temperaturas altas. El mayor reto de la tecnología solar es la limitada duración de la radiación (aproximadamente, 8 horas). Este problema puede superarse en parte mediante almacenamiento de energía térmica, entre las cuales el almacenamiento termoquímico de energía (TCES en inglés) es la menos desarrollada, pero posee la mayor densidad energética. Esta tesis examina diferentes sistemas TCES como complemento a las centrales de torre CSP. El enfoque propuesto consiste en utilizar reacciones químicas en estado sólido para almacenar calor. Aunque existen numerosos sistemas TCES, la tecnología CaCO3/CaO ha sido ampliamente estudiado debido a su alta densidad energética, amplia disponibilidad y bajo coste. Además, las temperaturas implicadas son adecuadas para su integración en CSP. En concreto, esta tesis doctoral evalúa el impacto de las condiciones de CO2 en circuito cerrado en las aplicaciones de TCES. La temperatura de calcinación supera los 900 °C para lograr una rápida descomposición, aunque provoca una desactivación más fuerte debido a la sinterización. Aquí, proponemos el uso de una presión absoluta de CO2 reducida para igualar la temperatura óptima de la torre CSP. La calcinación en condiciones de vacío suave de CO2 (a 0,1 y 0,01 bar) es similar al uso de una atmósfera inerte (como N2, Ar y He) para la descomposición de la caliza sin alterar la atmósfera de reacción. También, se, The extensive rely on fossil fuel sources, although it is the primarily responsible for the technological advancements since the industrial revolution, it has also contributed to the acceleration of climate change era. Among the main current societal challenges is the reduction of CO2 emissions into the atmosphere, which is derived from the burning of fossil fuels used mainly in thermal plants to produce energy. Renewable energies have emerged as a clean and viable alternative to decreasing the rate of greenhouse gases (GHG) and CO2 emissions. The deployment of renewable energy sources worldwide is extensive, although their intermittency is a significant hindrance to their universal application. Solar radiation is considered one of the most promising sources for reducing emissions and its integration with current available technologies is relevant. The Concentrated Solar Power (CSP) tower technology involves the concentration of solar radiation by heliostats onto a receiver on the top of a tower, allowing for high temperatures to be achieved. The greatest challenge for solar technology is the limited duration of solar time during the day (roughly, 8 h). This issue can be partially overcome through Thermal Energy Storage (TES) solutions, among which, the thermochemical energy storage (TCES) is the least developed but holds the highest energy density. This thesis examines different TCES solutions as a complement to CSP tower plants. The proposed approach involves utilizing solid-state chemical reactions to store heat. While there are a numerous TCES systems available, natural carbonate materials are considered the most promising option. Of these, the CaCO3/CaO system has been amply studied due to its high energy density, wide availability and low-cost. Moreover, the involved temperatures are suitable for integration into CSP. Specifically, this doctoral thesis evaluates the impact of closed-loop CO2 conditions on TCES applications. The calcination temperature exceeds

Magnetic Resonance Imaging (MRI) allows the visualization of organs and tissues for medical diagnosis. This technique is non-invasive, does not require the use of radioactive agents or high-energy electromagnetic waves, and has a high spatial resolution and a great image depth. Despite these advantages, in order to increase the contrast in these images between the region of interest and its surroundings, it is often necessary to use contrast agents (CAs), which are composed of magnetically active substances that shorten T1 and T2 proton relaxation times. Although MRI is well established in clinics, several modifications of this technique are being currently addressed with the aim of improving diagnostic reliability. In particular, high-field MRI and T1-T2 dual mode MRI have been proposed. The first one improves image resolution by using higher magnetic fields than those involved in conventional scanners (? 3 T). T1-T2 dual mode MRI involves recording bright and dark images simultaneously. By so doing, cross-validation of both types of images can be carried out, so that false positives can be excluded, and complementary information can be also obtained. Both advantages allow to increase diagnostic sensitivity and accuracy. Unfortunately, the conventional CAs used in clinics are not suitable for these novel techniques, for which, it is imperative to develop new contrast agents. For the high-field MRI technique, several alternatives have been considered. The most promising candidates are compounds based on Dy3+, since this ion has a very high magnetic moment (10.6 ?B), which leads to high transverse relaxivity values. For T1-T2 dual mode MRI, compounds based on Dy3+ ions as T2 component are equally interesting, and as T1 component, Gd3+ ions are usually used, which have a high spin angular momentum (7/2) that allows high values of longitudinal relaxivity. Different CAs have been reported in the literature, both for high-field MRI and T1-T2 dual mode MRI, consisting of, La técnica de obtención de imágenes por Resonancia Magnética (MRI, siglas en inglés) permite la visualización de órganos y tejidos para el diagnóstico médico. Esta técnica destaca por ser no invasiva, no requerir el uso de agentes radiactivos u ondas electromagnéticas de alta energía, poseer una alta resolución espacial y una gran profundidad de imagen. A pesar de estas ventajas, a veces es necesario aumentar el contraste entre la región de interés y su entorno, empleando agentes de contraste (ACs) que están constituidos por sustancias magnéticamente activas que acortan los tiempos de relajación T1 y T2 del protón. Los ACs que acortan T2 oscurecen la región de interés, mientras que aquellos que disminuyen el valor de T1 dan lugar a un mayor brillo de dicha región. Entre los primeros destacan los óxidos superparamagnéticos basados en óxido de hierro, y entre los segundos, los compuestos de Gd3+ en los cuales están basados los agentes de contraste comerciales. Aunque la técnica MRI está muy bien establecida en el ámbito clínico, se están abordando en la actualidad diversas modificaciones de la misma con el objetivo de mejorar la fiabilidad del diagnóstico. En concreto, se han propuesto la técnica de MRI a alto campo y la técnica de MRI dual T1 - T2. La primera supone emplear campos magnéticos más altos que los implicados en los escáneres usados en clínica (≤ 3 T), con el objeto de mejorar la resolución. La segunda permite aumentar la sensibilidad y exactitud del diagnóstico registrando imágenes brillantes y oscuras de forma simultánea, ya que, mediante la validación cruzada de ambos tipos de imágenes, se pueden excluir falsos positivos y, además, obtener información complementaria. Desafortunadamente, los ACs convencionales que se usan en clínica no son adecuados para la obtención de imágenes mediante estas técnicas por lo que es imperativo desarrollar nuevos agentes de contraste. Para la técnica de MRI a alto campo, se han desarrollado diversas alternativas siendo lo

The urgent need for mitigating climate change necessitates a transformative shift in energy production and consumption paradigms. Amidst this challenge, bioenergy emerges as a pivotal contributor to the global energy transition, offering a diverse array of solid, liquid, and gaseous fuels derived from biomass. This mini review delves into the unique potential of bioenergy innovations, particularly renewable diesel, bio jet fuel, and ethanol, to reduce greenhouse gas emissions and transform various industries. The article highlights critical technological advancements, supportive policies, and cross-sector collaboration essential for a sustainable energy transition. Specific challenges such as ensuring a consistent biomass feedstock supply, decentralizing processing units, and navigating complex regulatory frameworks are examined. Innovative solutions like decentralized biomass processing and enhanced biomass logistics are discussed as pathways to overcome these barriers. The review provides specific recommendations for near-term policies and strategies to support decentralized facilities, showcasing bioenergy’s role in achieving a sustainable future.

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.

In the search of versatile electrocatalysts for the electrochemical reduction of carbon dioxide (CO2RR), different transition metal phthalocyanines (MPc, where M=Fe, Co, Ni and Cu) have been immobilized by an easy and scalable wet impregnation on carbon nanotubes (CNTs) in the form of buckypaper (BP). Both the nature of the metal and the surface chemistry of the carbon support were found to play a pivotal role in determining their CO2RR efficiency and selectivity. We disclose here a potentiodynamic strategy for the controlled surface modification of BP with N- and P-containing polymeric species as a simple heterogenization strategy for molecular catalysts, enabling to easily tune their electrocatalytic performance. Syngas (mixture of H2 and CO) was obtained as the main product from CO2RR using FePc, CoPc and NiPc as electrocatalysts on functionalized (BPf) or non-modified BP. In contrast, CuPc was found to mainly catalyze the hydrogen evolution reaction (HER), with small amounts of formate as the only CO2RR product. It is possible to modulate the H2/CO ratio in the final product through the appropriate selection of the metal in MPc, the modification of the coordination environment by the controlled functionalization of the carbon support and the adjustment of the operating conditions. In particular, H2/CO ratios in a range between 0.17 and 1.28 have been obtained with good stability during electrolysis. Among all the MPc studied, CoPc surfaced as the most promising candidate for the reduction of CO2 to CO and H2 production, a finding substantiated by computational studies highlighting the positive impact of phosphate ligands on CoPc. This strategy outlines the starting line of a potential route toward the controlled generation of CO2RR-related products.

The present research describes one of the processes outlined in the literature, known as Chemical Looping Dry Reforming of Methane, which is currently to gain attraction to produce clean fuels from natural gas using a metal oxide support as a catalyst. This two-step method offers distinct advantages by physically separating the reaction steps. This spatial separation effectively eliminates undesirable side reactions, leading to highly efficient syngas production with minimal carbon deposition. Crucial to optimizing this process is a deep understanding of the oxygen storage capacity (OSC) of the support (oxygen carrier) that will work in synergy with the supported active phase. Among the candidates, praseodymium stands out due to its favourable redox properties and exceptional OSC characteristics, making it a promising option for cleaner fuel technologies. In particular, this study emphasizes the significant influence of the nature of the active phases (Ni, Co or their bimetallic combinations), with bimetallic phases being the most promising (even without reduction, they can exhibit activity that equals or improves that of the Ru as benchmark), underscoring the fundamental role of catalyst design in achieving optimal performance. The results indicate that these compositions have high activities to generate the products, remaining close to the activity of ruthenium and generating minimal coke deposits in one reaction cycle.

This review shows the endeavors performed to prepare immobilized formulations of bromelain extract, usually from pineapple, and their use in diverse applications. This extract has a potent proteolytic component that is based on thiol proteases, which differ depending on the location on the fruit. Stem and fruit are the areas where higher activity is found. The edible origin of this enzyme is one of the features that determines the applications of the immobilized bromelain to a more significant degree. The enzyme has been immobilized on a wide diversity of supports via different strategies (covalent bonds, ion exchange), and also forming ex novo solids (nanoflowers, CLEAs, trapping in alginate beads, etc.). The use of preexisting nanoparticles as immobilization supports is relevant, as this facilitates one of the main applications of the immobilized enzyme, in therapeutic applications (as wound dressing and healing components, antibacterial or anticancer, mucus mobility control, etc.). A curiosity is the immobilization of this enzyme on spores of probiotic microorganisms via adsorption, in order to have a perfect in vivo compatibility. Other outstanding applications of the immobilized enzyme are in the stabilization of wine versus haze during storage, mainly when immobilized on chitosan. Curiously, the immobilized bromelain has been scarcely applied in the production of bioactive peptides.

Currently, the production of complex SiC and SiC/SiC parts through reactive infiltration is one of the most widely used technologies, due to its versatility and cost-effectiveness compared to more conventional technologies such as Hot Isostatic Pressing (HIP). This technology, while widely adopted, still faces some debate regarding the mechanisms of infiltration. Questions persist about what determines how infiltration occurs and whether the process is governed by physics (flow dynamics) or chemistry (reactions at the triple line (LT: (contact line between the solid, liquid and gas phases)). The present work provides new strong/consistent proof that reactive infiltration is mainly controlled by chemical reaction.

Current methods for producing open-pore graphite foams with heat dissipation potential involve costly graphitization processes, limiting their widespread use. This study presents a sustainable approach to fabricate high-performance graphite/carbon composite foams with porosities in the range of 49–82 %. The method involves the densification and carbonization of solid mixtures comprising natural graphite flakes, sucrose, and NaCl particles. The dissolution of NaCl creates coarse pores, while carbonized sucrose contributes fine porosity and serves as a binder to impart mechanical stability, ensuring the maintenance of thermally conductive percolative contacts between flakes. The composite foams exhibit thermal conductivities of up to 91 Wm−1K−1, permeability values in the range of 10−11–10−10 m2, and excellent mechanical properties. Experimental and computational findings demonstrate that the developed materials surpass the heat dissipation capabilities of conventional heat sinks based on graphite and aluminum foams by about 3 and 1.5 times, respectively, making them excellent candidates for thermal management applications.

The particulate and soluble matter present in aerosols from combustible cigarettes (CCs) and Heated Tobacco Products (HTPs) was collected in liquid water. These liquids, yellowish in the experiments with cigarettes and colourless after using HTPs, were analysed by Laser Diffraction (LD) and by Transmission Electron Microscopy coupled to Energy Dispersive X-ray spectroscopy (TEM-EDX) to study the amount, size, composition, and other features of the particulate matter (PM) present in the collected aerosols. The particulate matter concentration in HTPs samples is below the limit of quantification for LD, and only samples from cigarettes show a particulate matter concentration above such limit. TEM analysis has revealed that the liquid samples (from both, cigarettes and HTPs experiments) contain particulate matter, mainly composed of carbon (C) and oxygen (O), but also of traces of inorganic elements. The TEM electron beam results in the evaporation of the particulate matter derived from HTPs, but not of that derived from cigarettes, highlighting the different nature of the particulate matter in both systems, i.e. liquid particulate matter present in the HTPs aerosols and solid particulate matter in the cigarettes smoke. A protocol for the quantitative comparison of the particulate matter present in aerosols has been applied over sixteen TEM images for each sample, confirming important differences from the point of view of the amount of particulate matter and particle size ranges. Thus, the amount of particulate matter for HTPs aerosol samples is more than one order of magnitude lower than for cigarettes smoke.

In this paper, we offer new porous activated carbons (PACs) made from waste Argan pulp for use in solid-state supercapacitors. The synthesis is a two-step process of carbonization and KOH activation, with temperatures ranging from 700 to 850 °C and ratios ranging from 1:3 to 1:4. The carbon material obtained exhibits a significant surface area ranging from 2757 to 3235 m2 g−1. The evaluation of electrochemical characteristics in a two-electrode system using a 1 M H2SO4 electrolyte reveals exceptional capacitance and specific energy when subjected to a current density of 125 mAg-1. The AP-800-3 has outstanding performance, with a specific capacitance of 460 F g−1 and a specific energy of 15.98 Wh kg−1. Significantly, this particular PAC has exceptional durability in cycling, as it maintains its full specific capacitance even after undergoing 2500 charge and discharge cycles at a rate of 1 A.g−1. When testing with 6 M KOH and 1 M Na2SO4 electrolytes, the capacitance is found to be lower compared to 1 M H2SO4 (239 F g−1 and 258 F g−1, respectively). The superior performance in 1 M H2SO4 emphasizes the interplay between electrolyte composition, porosity, and appropriate microstructure of the PACs. This study proposes eco-friendly method for selecting supercapacitor electrode materials.

In response to the environmental impacts of conventional polyurethane adhesives derived from fossil fuels, this study introduces a sustainable alternative utilizing lignin-based polyols extracted from rice straw through a process developed at INESCOP. This research explores the partial substitution of traditional polyols with lignin-based equivalents in the synthesis of reactive hot melt polyurethane adhesives (HMPUR) for the footwear industry. The performance of these eco-friendly adhesives was rigorously assessed through Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), rheological analysis, and T-peel tests to ensure their compliance with relevant industry standards. Preliminary results demonstrate that lignin-based polyols can effectively replace a significant portion of fossil-derived polyols, maintaining essential adhesive properties and marking a significant step towards more sustainable adhesive solutions. This study not only highlights the potential of lignin in the realm of sustainable adhesive production but also emphasises the valorisation of agricultural by-products, thus aligning with the principles of green chemistry and sustainability objectives in the polymer industry.

Environmentally friendly polymers such as cellulose acetate (CA) and chitosan (CS) were used to obtain electrospun fibers for Cu2+, Pb2+, and Mo6+ capture. The solvents dichloromethane (DCM) and dimethylformamide (DMF) allowed the development of a surface area of 148 m2 g−1 for CA fibers and 113 m2 g−1 for cellulose acetate/chitosan (CA/CS) fibers. The fibers were characterized by IR-DRIFT, SEM, TEM, CO2 sorption isotherms at 273 K, Hg porosimetry, TGA, stress-strain tests, and XPS. The CA/CS fibers had a higher adsorption capacity than CA fibers without affecting their physicochemical properties. The capture capacity reached 102 mg g−1 for Cu2+, 49.3 mg g−1 for Pb2+, and 13.1 mg g−1 for Mo6+. Furthermore, optimal pH, adsorption times qt, and C0 were studied for the evaluation of kinetic models and adsorption isotherms. Finally, a proposal for adsorbate-adsorbent interactions is presented as a possible capture mechanism where, in the case of Mo6+, a computational study is presented. The results demonstrate the potential to evaluate the fibers in tailings wastewater from copper mining.

Addressing contemporary environmental and health concerns requires reducing pollutant emissions and converting them into less harmful or valuable compounds within the framework of the circular economy. Guefoam materials offer a promising solution by enabling the capture and pre-concentration of volatile organic compounds (VOCs), while facilitating the structuring of active phases for heterogeneous catalytic conversions. This study demonstrates the benefits of merging two newly designed electromagnetic induction-assisted ceramic matrix Guefoams into a portable integrated unit, synergizing the pre-concentration and chemical transformation of n-hexane, a VOC with special challenges. One Guefoam serves as an adsorbent, whereas the other plays a catalytic role. These Guefoams host guest phases, which consist of composite materials combining a steel core with magneto-inductive properties encased in a highly porous carbonaceous layer. This carbonaceous material undertakes a dual mission: adsorbing n-hexane from a nitrogen stream within the adsorptive Guefoam and, upon phosphorus doping in the catalytic Guefoam, orchestrating the metal-free selective dehydroaromatization of n-hexane into benzene. The design and integration of these novel Guefoam materials into a unified functional entity prove highly effective in pre-concentrating (enrichment factors up to 275) and catalyzing n-hexane with up to 84 % conversion and 94 % benzene selectivity while remaining energy-efficient and environmentally sustainable.

Carbon materials have emerged as a new generation of catalysts for the crucial industrial hydrogenation of nitroarenes. Activated carbon, known for its cost-effectiveness and facile modifiability, stands out among various carbon materials. This study focuses on the preparation of N and P co-doped carbons for catalysing the hydrogenation of 1-chloro-4-nitrobenzene. Comprehensive characterisation using thermal analysis (TGA-MS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, N2 adsorption at -196 ºC, and ICP-MS was performed. The synergistic effect of N and P was evident, with co-doped carbons outperforming their mono-doped counterparts, underscoring the significance of nitrogen. N,P-codoped activated carbon emerges as a promising, active, stable, and selective metal-free catalyst for the hydrogenation of 1-chloro-4-nitrobenzene, leading to 4-chloroaniline.

In the present work, a series of supports with varying compositions (ranging from pure CeO2 to pure PrO2-y) was designed to investigate their ability to release oxygen (with the concomitant formation of oxygen vacancies) under diverse reducing atmospheres: hydrogen (H2), helium (He), and in the presence of a carbonaceous substance that mimics eventual carbon deposits formed under practical reaction conditions (DRM). Oxygen vacancies were generated effectively in all three atmospheres (following the order He < H2 < carbon material). With regard to the influence of the composition, the capability to generate oxygen vacancies clearly increased with the Pr content, for whatever the conditions tested. Notably, the non-stoichiometry obtained with the support of pure praseodymia in both inert and reducing atmospheres is very remarkable, as it approaches the maximum non-stoichiometry value of the well-established theoretical Bevan cluster. This leads to consider this formulation as a very promising support for applications in catalysis and other fields where oxygen vacancies play a crucial role. Dry Reforming of Methane requires catalytic supports that possess highly mobile oxygen, enabling it to actively participate in the reactions step involved or potentially gasify undesirable carbon deposits generated during parallel reactions. Consequently, designing and elucidating the behavior of ceria-praseodymium-based supports with high reducibility and generation of oxygen vacancies (oxygen storage and release capacity) holds particular relevance in this context. Actually, the very preliminary results comparing two counterpart formulations (5%Ni/PrO2-y versus 5%Ni/Al2O3) already confirm the suitability of the choice of pure praseodymia in terms of activity, stability and very high selectivity towards H2 and CO, reaching a very close value to the ideal H2/CO ratio of 1.

The present research exploits an innovative methodology for producing auto-pressurized carbon microreactors with a precise and controlled structure analyzing the influence of their design on the fluid dynamics and their catalytic performance. Carbon monoliths with Tesla-valve shape channels (Tesla, T, and modified Tesla, Tm) are synthesized through the combination of 3D printing and sol–gel process and further probed as Ni/CeO2 supports on CO2 methanation. The experimental results and mathematical modeling corroborated the improved performance obtained through the complex design compared to a conventional one. In addition to chaotic fluid flow induced by the deviation in flow direction, which improves the reagents-active phase interaction, local pressure increases due to convergence of flows may enhance the Sabatier reaction according to Le Châtelier's principle. Conversely to straight channels, T and Tm are not affected by flow rate and presented chemical control. Tesla-valve with curved angle (Tm) improved the mass transfer, achieving higher conversion and ≈30% reaction rate increase regarding right angle (T). Thus, this auto-pressurized multi-stage Tesla-valve monolith opens the gate to design specific and advanced functional materials for multitude chemical reactions where not only the reactant-active phase contact can be maximized but also the reaction conditions can be controlled to maximize the reaction kinetics.

El dióxido de carbono (CO₂) es uno de los principales gases de efecto invernadero responsables del calentamiento global y el cambio climático. Las elevadas concentraciones de CO₂ en la atmósfera, derivadas de actividades humanas como la quema de combustibles fósiles y la deforestación, contribuyen significativamente al aumento de la temperatura global, provocando efectos adversos en el medio ambiente y en los ecosistemas. Una estrategia crucial y novedosa para mitigar el impacto ambiental del CO2 es su fotorreducción y conversión en productos de valor añadido. En este trabajo se estudia el desarrollo de fotocatalizadores a base de dióxido de titanio (TiO₂) impregnados con cobre (Cu) para la fotorreducción de dióxido de carbono a metano (CH₄). Para ello, se han sintetizado fotocatalizadores P25/Cu y P90/Cu mediante la técnica de impregnación húmeda, utilizando TiO₂ comercial (P25 y P90). El objetivo principal de este Trabajo de Fin de Grado es la comparación de los fotocatalizadores puros con los impregnados con cobre, así como el uso de diferentes titanias como la P25 y la P90 para la reducción de CO2. Las muestras se han caracterizado utilizando técnicas como espectroscopía de emisión óptica por plasma de acoplamiento inductivo (ICP-OES), difracción de rayos X (DRX), adsorción de gases (N₂), microscopía electrónica de transmisión (TEM), microscopía electrónica de barrido (SEM), espectroscopía fotoelectrónica de rayos X (XPS), medida del potencial Z, espectroscopía ultravioleta-visible (UV-Vis), fotoluminiscencia (PL) y espectroscopía fotoelectrónica ultravioleta (UPS). Además, se han realizado ensayos fotocatalíticos mediante un reactor de flujo y su posterior análisis con un cromatógrafo de gases con detectores FID y TCD para evaluar su eficiencia catalítica. Los resultados obtenidos muestran que el dopado con cobre mejora la eficiencia catalítica del TiO₂ al reducir la recombinación de pares electrón-hueco. Sin embargo, se observa que la efectividad de los fotoca

Capítulo I. Introducción. El uso creciente de fertilizantes nitrogenados es responsable de la permeación de especies de nitrógeno a través de las capas del suelo y de la contaminación de las aguas subterráneas. El consumo humano de agua con altos niveles de nitratos (el nivel máximo permitido es de 50 mg·L-1) puede producir metahemoglobinemia y hasta cáncer. Los nitratos pueden reducirse a nitritos en el cuerpo humano. El nitrito se combina con la hemoglobina, que contiene el ion ferroso (Fe2+), para formar la metahemoglobina, que contiene la forma férrica (Fe3+) del hierro. La mayor afinidad de la metahemoglobina por el oxígeno conduce a una reducción general de la capacidad de los glóbulos rojos para liberar oxígeno a los tejidos. Cuando la concentración de metahemoglobina es demasiado alta en los glóbulos rojos, se puede producir hipoxia tisular. Esta enfermedad, conocida como el síndrome del bebé azul, es fatal para el recién nacido. Se dispone de procesos fisicoquímicos, biológicos y catalíticos para eliminar los nitratos del agua. Los métodos fisicoquímicos, como el intercambio iónico, la ósmosis inversa y la electrodiálisis, eliminan los nitratos del agua potable, pero los concentran en otros lugares, con el consiguiente problema de eliminación de la salmuera generada de los residuos de nitratos. La desnitrificación biológica transforma los nitratos en nitrógeno molecular, pero es difícil de realizar y puede convertirse en otra fuente de contaminación del agua con bacterias. La reducción catalítica de las especies de nitrato para formar nitrógeno se ha considerado como una tecnología alternativa para la reducción de nitratos. La reducción de nitratos se realiza generalmente con hidrógeno (H2) en presencia de catalizadores metálicos. Se pueden utilizar sistemas monometálicos como Pt o Pd, y también sistemas bimetálicos que combinan un metal hidrogenante (Pd, Pt) y un metal promotor (Cu, In, Sn), dispersados en diferentes soportes con una superficie específica

Due to the need for decarbonization in energy generation, it is necessary to develop electrocatalysts for the oxygen reduction reaction (ORR), a key process in energy generation systems such as fuel cells and metal–air batteries. Perovskite–carbon material composites have emerged as active and stable electrocatalysts for the ORR, and the interaction between both components is a crucial aspect for electrocatalytic activity. This work explores different mixing methods for composite preparation, including mortar mixing, ball milling, and hydrothermal and thermal treatments. Hydrothermal treatment combined with ball milling resulted in the most favorable electrocatalytic performance, promoting intimate and extensive contact between the perovskite and carbon material and improving electrocatalytic activity. Employing X-ray photoelectron spectroscopy (XPS), an increase in the number of M-O-C species was observed, indicating enhanced interaction between the perovskite and the carbon material due to the adopted mixing methods. This finding was further corroborated by temperature-programmed reduction (TPR) and temperature-programmed desorption (TPD) techniques. Interestingly, the ball milling method results in similar performance to the hydrothermal method in the zinc–air battery and, thus, is preferable because of the ease and straightforward scalability of the preparation process.

The present manuscript focuses on important aspects regarding TiO2, which is typically used in many applications. On one hand, a thorough review of methods for synthesizing nanostructured TiO2 is presented. Using these methods, and different post-synthesis heat-treatment conditions, close to thirty TiO2 materials have been prepared, and their porous texture and crystalline and amorphous structure have been characterized. In this large number of samples, the porous texture characterization has revealed a high contribution of mesoporosity in a large number of the synthesized materials, being in many materials around 60–70 %. Moreover, different percentages of crystalline phases, anatase, brookite, rutile, and amorphous titania are developed depending on the TiO2 preparation conditions. These fractions have been determined from X-ray diffraction data using the “simple” characterization method reported by Cano-Casanova et al., inspired by Jensen et al., and Bellardita et al., also exploring its limitations. This analysis has allowed assessing a linear relationship between porosity, particularly between the surface area, and the amorphous phase content in titanium dioxide. A relationship had been previously suggested in the literature, but never correlated in such a way. In summary, the present study constitutes a tool to help other researchers select the most suitable method for synthesizing nanostructured TiO2 materials with target properties and, also, to characterize them, and have a very easy and straightforward estimation of TiO2 amorphous phase content after the determination of their surface areas.

This study addresses the critical need to reduce energy penalties in CO2 capture processes by exploring the potential of activated carbons derived from argan paste cake for post-combustion CO2 capture applications. Leveraging their cost-effectiveness, stability in humid conditions, and microporous structure, a series of activated carbons with diverse textural characteristics were synthesized through a two-step chemical activation process employing a KOH: biochar ratio of 1:1. Activation temperatures ranged from 700 to 850 °C. Characterization techniques such as Raman spectroscopy, X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, elemental analysis, and Fourier-transform infrared spectroscopy were employed to analyze the structural and chemical properties of the synthesized activated carbons. Remarkably, all synthesized samples exhibited excellent CO2 adsorption properties. Notably, the activated carbon sample prepared at 700 °C (APC-500–700) demonstrated the highest CO2 adsorption capacity, reaching up to 4.89 mmol/g at 0 °C and 2.98 mmol/g at 25 °C. Additional samples, including APC-500–800 and APC-500–850, exhibited CO2 adsorption capacities of 4.89 mmol/g and 4.83 mmol/g, respectively, at 0 °C, with corresponding values of 2.74 mmol/g and 2.60 mmol/g observed at 25 °C. Selectivity and stability tests were conducted to evaluate the adsorption performance under varied conditions, further highlighting the potential of activated carbon derived from argan paste cake in contributing to efficient CO2 capture processes. These findings underscore the significance of synthesis conditions in tailoring adsorption performance and pave the way for the sustainable utilization of waste biomass for environmental applications.

Ba1−xCexMnO3 (BM-Cex) and Ba1−xLaxMn0.7Cu0.3O3 (BMC-Lax) perovskite-type mixed oxides were synthesized using the sol–gel method adapted for aqueous media with different values of x (0, 0.1, 0.3, 0.6) to estimate the effect of the degree of the partial substitution of Ba by Ce or La on the structure and properties that are relevant for their use as catalysts for gasoline direct injection (GDI) soot oxidation. The samples were deeply characterized by ICP-OES, XRD, XPS, N2 adsorption, H2-TPR, and O2-TPD, and their potential as catalysts for soot oxidation has been analyzed in various scenarios that replicate the exhaust conditions of a GDI engine. By comparing the catalytic performance for soot oxidation of the two tested series (BM-Cex and BMC-Lax) and in the two conditions used (100% He and 1% O2 in He), it could be concluded that (i) in the absence of oxygen in the reaction atmosphere (100% He), BMC-La0.1 is the best catalyst, as copper is also able to catalyze the soot oxidation; and (ii) if oxygen is present in the reaction atmosphere (1% O2/He), BM-Ce0.1 is the most-active catalyst as it presents a higher proportion of Mn(IV) than BMC-La0.1. Thus, it seems that the addition of an amount of Ce or La higher than that corresponding to x = 0.1 in Ba1−xCexMnO3 and Ba1−xLaxCu0.3Mn0.7O3 does not allow us to improve the catalytic performance of BM-Ce0.1 and BMC-La0.1 for soot oxidation in the tested conditions.

Nitrogen-doped carbons were obtained by the pyrolysis of polyaniline (PANI), which had been previously synthesized by chemical oxidative polymerization of aniline at two different temperatures (0 and 25 °C). A series of activation treatments with steam under different experimental conditions were carried out in order to develop carbon porosity. It has been shown that the experimental polymerization conditions greatly affect the properties of the N-doped carbons and their reactivity to the steam activation treatment. Carbons were characterized by N2 adsorption at −196 °C, CHNS Elemental Analysis and XPS and their hydrophilicity/hydrophobicity were assessed by water adsorption measurements. The carbons prepared from PANI synthesized at 0 °C showed a more developed porosity and specific surface area than those obtained from PANI synthesized at 25 °C. The increase in the activation temperature produces the loss of the nitrogen heteroatom. Adsorption of water and toluene depends on the amount of surface nitrogen atoms as well as on the pore structure developed in the carbon.

The use of sacrificial agents in photocatalysis is a powerful resource to enhance the performance of photoactive materials. Despite its importance, the effect of the amount of sacrificial agent is not properly described in the literature. In this paper, we have focused on the role of EtOH in the photoreduction of CO2 to CH4 using Cu-P25 photocatalysts in a flow reactor. We found that the production of CH4 increased with the concentration of EtOH, achieving an outstanding CH4 production yield of 235 µmol/(g·h) for a flow of 0.25 µmol/min of EtOH in the gas stream, hinting at the important role of the sacrificial agent in the reaction. The catalytic results together with the characterization of the materials highlight the need to achieve a minimum surface coverage of EtOH on the surface of the catalyst to control the reaction pathway. The adsorption of EtOH is a key factor in boosting the catalytic activity of the best-performing catalyst and producing CH4 from CO2 photoreduction and C2H4O from the photooxidation of EtOH, obtaining two easily separable interesting products for industrial applications in one reaction.

The ongoing search for innovative and environmentally friendly luminescent materials coupled with customizable physical and chemical properties at the nanoscale positions carbon dots (CDots) as ideal candidates for photonic applications. However, even today, their rational design for specific applications remains elusive due to the unknown relationship between optical and structural properties. Therefore, this study aims to fill this gap by linking the chemical structure of the precursor and synthetic conditions to the final structural composition of the CDots and, by extension, to their optical properties. The study shows that while CDots are chemically stable, their optical properties, which are determined by the carbonaceous core and surface groups, are highly pH dependent. These properties, together with the long fluorescence lifetimes observed in living cells (>10 ns), make these biomass-derived CDots promising probes for time-resolved fluorescence imaging.

Activated carbon (AC) is a common material of choice in catalysis, as it is a suitable support material for many catalytic reactions. In this work, the effect of cobalt nanoparticles on activated carbon derived from a biomass waste, peach stone, is reported. The presence of cobalt during heat treatments at 900 °C under reductive (H2) and inert (He) atmospheres resulted in the appearance of an intense 2D band in the Raman spectra, indicating a high degree of graphitization. Temperature-programmed reduction and desorption experiments were conducted to evaluate the activation reactions. Quenched solid density functional theory (QSDFT) analysis using N2 adsorption data revealed that cobalt increased pore development in the samples, regardless of the atmosphere (reductive or inert) used.

During our past General Assembly in The Hague, IUPAC took a significant step forward in fostering international cooperation among chemical societies by launching the inaugural Presidents’ Forum. This initiative aims to bring together the leaders of chemical societies and federations from around the world to collectively address key issues in chemistry, with the goal of fostering mutual cooperation and increasing the global impact of chemistry for the betterment of humankind and the planet.

In this study, the effect of the cell density of monolithic catalysts was investigated and further mathematically modeled on cordierite supports used in CO2 methanation. Commercial cordierite monoliths with 200, 400, and 500 cpsi cell densities were coated by immersion into an ethanolic suspension of Ni/CeO2 active phase. SEM–EDS analysis confirmed that, owing to the low porosity of cordierite (surface area < 1 m2 g−1), the Ni/CeO2 diffusion into the walls was limited, especially in the case of low and intermediate cell density monoliths; thus, active phase was predominantly loaded onto the channels’ external surface. Nevertheless, despite the larger exposed surface area in the monolith with high cell density, which would allow for better distribution and accessibility of Ni/CeO2, its higher macro-pore volume resulted in some introduction of the active phase into the walls. As a result, the catalytic evaluation showed that it was more influenced by increments in volumetric flow rates. The low cell density monolith displayed diffusional control at flow rates below 500 mL min−1. In contrast, intermediate and high cell density monoliths presented this behavior up to 300 mL min−1. These findings suggest that the interaction reactants-catalyst is considerably more affected by a forced non-uniform flow when increasing the injection rate. This condition reduced the transport of reactants and products within the catalyst channels and, in turn, increased the minimum temperature required for the reaction. Moreover, a slight diminution of selectivity to CH4 was observed and ascribed to the possible formation of hot spots that activate the reverse water–gas shift reaction. Finally, a mathematical model based on fundamental momentum and mass transfer equations coupled with the kinetics of CO2 methanation was successfully derived and solved to analyze the fluid dynamics of the monolithic support. The results showed a radial profile with maximum fluid velocity located at the cente