Direct ammonia solid oxide fuel cells (DA-SOFCs) have attracted increasing attention as high-temperature electrochemical energy conversion systems. However, endothermic ammonia cracking and limited hydrogen availability negatively impact performance. This work investigates the influence of hydrogen–ammonia fuel composition and operating temperature on DA-SOFC performance. An electrolyte-supported SOFC employing a SrFe0.9Ru0.1O3 perovskite cathode and a Ni-GDC anode is experimentally characterized between 650 ∘C and 750 ∘C furnace temperature under pure H2 and NH3. Additionally, a three-dimensional multiphysics model implemented in COMSOL Multiphysics® simulates the cell under these operating conditions as well as a 50/50M H2/NH3 blend fuel. The simulated performance reduction with increasing ammonia content, of up to 67% at 750 ∘C, is explained by hydrogen dilution and localized cooling induced by endothermic reactions. The results demonstrate that an ammonia-hydrogen blend offers an effective compromise between power output and hydrogen requirements.

Bio-based alternatives to standard insulation and building systems are being thoroughly investigated because of the urgency of eco-friendly building materials that use less energy and produce fewer carbon emissions. Mycelium-based composites (MBCs) have attracted research enthusiasm all over the world; they are developed by growing mycelium over lignocellulosic residues, and these MBCs are low in density, porous, and biodegradable in nature. Recent studies underscore their potential in thermal and acoustic applications where these intrinsic properties are beneficial. In the context of burgeoning literature, this review singularly offers a comprehensive engineering assessment that simultaneously addresses thermal and acoustic design strategies for mycelium-based composites. Main recommendations are tailoring pore structure, hybridizing with complementary materials such as aerogels and phase change materials, and designing multi-layered systems to optimize sound absorption and thermal conductivity. However, limitations in the mechanical properties, water resistance, scalability, and the absence of consistent testing standards pose a challenge in benchmarking MBCs against conventional materials. Future studies must emphasize the enhancement of material uniformity, multifunctionality, and standard evaluation assessment for facilitating their wider utilization in the construction industry. Overall, MBCs drive the sustainable economy for an energy efficient and healthier in-built environment in building and construction.

The Ti2AlN MAX phase is known for its unique blend of metallic and ceramic properties, including high electrical and thermal conductivity and excellent oxidation and corrosion resistance. This study focuses on the influence of the mechanical activation process on the electrochemical properties of Ti2AlN in a saline environment. High-purity powders of AlN and Ti were mechanically activated or mixed and sintered to synthesize the Ti2AlN MAX phase. The electrochemical behavior was assessed through potentiodynamic curves and electrochemical impedance spectroscopy, while surface characteristics were analyzed using SEM-EDS and XPS post-exposure to a 3.5% NaCl solution. Results reveal that Ti2AlN forms protective Al2O3 and TiO2 layers, enhancing its corrosion resistance. Mechanically activated samples (MAP) displayed different corrosion behavior than non-activated samples (NMAP), with MAP showing reduced corrosion resistance. This discrepancy is attributed to differences in oxide formation and microstructural changes due to mechanical activation. This research not only elucidates the corrosion mechanisms of MAX phases in chloride-rich environments but also analyzes the effect of mechanical processing on their properties, contributing to developing Ti2AlN applications where high durability and resistance are critical.

Global energy demand has increased significantly due to world population growth and the industrialization of developing economies. Its production has been based mainly on fossil-fuel energy, increasing the global warming effect upon the rise of greenhouse gases in the atmosphere, such as carbon dioxide (CO 2 ). In this context, the International Energy Agency reported that the global temperature will increase by 2.7 °C by 2100, which can be decreased by using renewable energies, as written by the United Nations Framework Convention on Climate Change. Moreover, according to the last report of the Intergovernmental Panel on Climate Change, it is crucial to substantially reduce CO 2 emissions and other greenhouse gases to improve air quality and stabilize global temperatures. However, nowadays, world energy generation from renewable resources, such as wind, solar, hydroelectric, biomass, tidal, and geothermal, only corresponds to 40%. Fuel cell technology is an excellent opportunity for reducing the dependence on fossil fuels and carbon footprint production. FC uses clean energy with a high conversion efficiency and system configuration that facilitates the easy capture of CO 2 . Different FC exists according to the operation temperature, the electrolyte chemical nature, and the fuel, increasing the conversion efficiency at higher temperatures, such as in Molten Carbonate Fuel Cells and Solid Oxide Fuel Cells, or even more recent Hybrid Fuel Cells, combining both previously mentioned technologies. Although FC has existed for decades, challenges exist to improve its efficiency. Therefore, developing new functional materials for innovative devices or applications is crucial in our changing world. New paradigms are necessary to produce cleaner energy or cheaper and more efficient materials for transport or other domains. This work focuses on the corrosion performance of a nickel-aluminum bronze alloy (NAB) obtained by laser powder bed fusion exposed to molten carbonate at high temperatures under a hydrogen/nitrogen atmosphere. Using electrochemical measurements and surface analyses, NAB samples were monitored before and after 120 hours of exposure between 550 and 650 °C. Scanning electron microscopy and X-ray photoelectron spectroscopy of NAB demonstrated that an oxide film was formed on the NAB surface, rich in Al 2 O 3 and Cu 2 O. Open circuit potential and impedance analysis of NAB revealed that the oxide film was stable under the exposure condition. In addition, the impedance analyses showed a capacitive behavior associated with a porous behavior, relate to the oxide film, and a Warburg impedance.

This study evaluates the corrosion behavior of Fe-22Mn-0.6C TWIP steels containing 0%, 5%, and 10% chromium after 28 days of exposure to a neutral sulfate solution. By combining electrochemical testing with a surface and spectroscopic analysis, we explored how Cr influences the formation and stability of oxide layers. The results reveal a clear trend: as the chromium content increases, the corrosion resistance improves significantly. The 10% Cr alloy stood out for its high impedance and stable electrochemical response, pointing to the development of a dense, protective oxide layer that limits the corrosive attack. The SEM/EDS and Raman spectroscopy revealed that chromium not only enhances the oxide’s compactness but also alters its composition, transitioning from iron-rich, porous oxides to Cr-containing spinels and oxyhydroxides with superior barrier properties. These structural and chemical improvements were confirmed by electrochemical parameters, which showed a reduced capacitance and increased film homogeneity. To tie these findings together, we propose a schematic model describing how chromium shapes the passivation process in these steels. Altogether, this study highlights the essential role of Cr in enhancing long-term corrosion protection in high-Mn TWIP steels under sulfate-rich conditions.

Ammonia is one of the most important inputs in the global chemical industry, used primarily in fertilizers and explosives. It is increasingly recognized as a potential energy carrier. Its production is dominated by the Haber-Bosch process, which requires high energy consumption and significant capital investment, and contributes significantly to greenhouse gas emissions. For this reason, electrochemical pathways have become a possible sustainable alternative, as they operate under mild conditions and can be powered by renewable energy. However, the development of electrocatalysts that simultaneously achieve high selectivity, activity, and long-term stability remains a major challenge for this type of industry. Among emerging materials, graphene-derived carbon systems stand out for their high conductivity, large surface area, and tunable electronic properties, which can improve nitrogen adsorption and stabilization of potential reaction intermediates. This review summarizes the latest advances in the electrochemical synthesis of ammonia, with an emphasis on carbon-based electrocatalysts and their structure-performance relationships. Current challenges are analyzed, and future research directions are proposed to accelerate the development of environmentally friendly ammonia production strategies beyond the Haber-Bosch process.

In the field of solar thermal storage systems, metallurgical industry by-products have been proposed as filler materials for packed-bed thermal energy storage due to their low cost and suitable thermophysical properties. One of these by-products is copper slag, which has emerged as a competitive option compared to other types of industrial by-products. However, further research of its properties, composition, and heterogeneity is needed to fully address its potential as a storage medium. Approximately 2.2 tons of copper slag is produced per ton of copper extracted, posing disposal challenges for mining companies. Hence, there is growing interest in finding secondary uses for these slags. The present study investigated samples of copper slag from a Chilean foundry disposal site. Elemental and mineral characterization revealed that this heterogeneous material has high iron content with both amorphous and crystalline phases present. The evaluation of thermophysical properties showed stable specific heat capacity that increases with temperature within the range of 100 degrees C to 450 degrees C. However, these profiles exhibit variability in heat capacity, particularly at higher temperatures, which decreases with subsequent heating cycles. The results suggest that copper slag has potential as an alternative material for sensible heat storage in packed-bed systems, nonetheless, assessing the variability of its thermophysical properties is crucial to establish its feasibility for sustainable energy solutions.

Ammonia is gaining significant importance as a renewable energy carrier, driving global interest in sustainable production methods, such as electrochemical nitrogen or nitrate reduction. Due to the low yield in electrochemical ammonia synthesis, research on new catalyst materials, such as high-entropy alloys, has become increasingly significant, necessitating a deeper analysis of their catalytic behavior. In this context, electrochemical impedance spectroscopy is a valuable and versatile technique. This review presents a comprehensive impedance analysis of high-entropy alloys as catalysts for the electrochemical nitrogen reduction reaction and nitrogen oxoanions reduction reaction for ammonia generation at room temperature, highlighting the complexity of the system and the need for a multidisciplinary approach to understand the microstructural and electrochemical mechanisms.

Using fatty acids has generated significant interest in the building sector for improving energy storage in the form of latent heat. In this work, using vacuum impregnation, we analyzed the properties of a capric acid and myristic acid eutectic (83-17%) as a bio-based phase change material in Pinus radiata. The delignification of Pinus radiata samples facilitated the impregnation process, which was carried out using the Kraft pulping method. Morphological, chemical, mechanical, thermal, and acoustic impedance analyses were performed. The results revealed that impregnating PCM in Pinus radiata samples increases the thermal inertia of the impregnated samples, which is comparable to that of delignified samples. Additionally, the analyses showed no significant difference between natural and delignified samples after treatment with PCM.

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This work presents the effect of CeO2 nanoparticles (CeO2–NPs) on Cu–50Ni–5Al alloys on morphological, microstructural, degradation, and electrochemical behavior at high temperatures. The samples obtained by mechanical alloying and spark plasma sintering were exposed to a molten eutectic mixture of Li2CO3–K2CO3 for 504 h. The degradation of the materials was analyzed using gravimetry measurements and electrochemical impedance spectroscopy. Different characterization techniques, such as X-ray diffraction and scanning electron microscopy, were used to investigate the phase composition, parameter lattice, and microstructure of Cu–Ni–Al alloys reinforced with CeO2–NPs. The hardness of the composite was also examined using the Vickers hardness test. Gravimetry measurements revealed that the sample with 1 wt.% CeO2–NPs presented the best response to degradation with a less drastic mass variation. Impedance analysis also revealed that by adding 1 wt.% CeO2–NPs, the impedance modulus increased, which is related to a lower porosity of the oxide film or a thicker oxide layer. The microhardness also significantly increased, incorporating 1 wt.% CeO2–NPs, which reduced with higher CeO2–NPs content, which is possibly associated with a more uniform distribution using 1 wt.% CeO2–NPs in the Cu–Ni–Al matrix that avoided the aggregation phenomenon.

Global energy demand has increased significantly due to world population growth and the industrialization of developing economies. Energy production has been based mainly on fossil-fuel energy, which has increased global warming due to the rise of greenhouse gases in the atmosphere, such as carbon dioxide. According to the Energy Institute, renewable power generation through wind, solar, and other renewable sources, represent only 40,86% of energy sources in 2022 [1]. An alternative energy source for fossil fuels is hydrogen, which can be produced through renewable resources that increase energy efficiency. However, the storage and transportation of hydrogen present a series of technical challenges, resulting in high costs and motivating the development of intermediate technologies. Recently, ammonia generated by renewable energy sources has gained significant attention as an energy carrier, a medium to store and transport chemical energy, and directly as fuel [2]. Ammonia is also a primary raw material for making inorganic fertilizers, pharmaceuticals, synthetic fibers, resins, and other applications, benefiting nearly half the world's population. Ammonia can be transported more efficiently and safely than hydrogen in tanker vessels or pipelines due to its relative ease of being liquefied at room temperature and moderate pressure, increasing energy density. Currently, ammonia is produced mainly from hydrogen and nitrogen by the Haber-Bosch process, which utilizes fossil fuel, thus resulting in carbon dioxide emissions. Ammonia production can also involve the non-spontaneous nitrogen reduction reaction by electrochemical techniques, which uses hydrogen that can be provided from the water, reducing energy consumption and carbon dioxide emissions. However, the non-spontaneous nitrogen reduction reaction has low activity, and its voltage is close to that of the hydrogen evolution reaction. Plasma and electrothermal chemical cycle methods have been explored to improve the selectivity of non-spontaneous nitrogen reduction reactions. Several studies have proposed new catalysts to increase the active sites, modify the size and morphology of particles, and introduce defects, such as transition metal-based catalysts, carbon-based catalysts, phosphorus-based catalysts, etc. Nevertheless, traditional catalysts frequently degrade rapidly due to the harsh chemical environment and the inherent corrosiveness of the reactions involved. A highly active catalyst that degrades quickly due to corrosion offers limited practical value. Researchers are exploring novel materials like high-entropy alloys (HEAs) to address this challenge, which also have high corrosion resistance [3]. This study focuses on the potential of a HEA, FeCrMnNiCo, as a catalyst for the electrochemical conversion of nitrogen to ammonia via the electrochemical method, evaluating the influence of the microstructure on its mechanical properties, catalytic activity, and corrosion resistance. A ball burnishing deformation was applied to the HEA at different conditions. The X-ray diffraction revealed that the FeCrMnNiCo alloy presented a face-centered cubic crystalline structure, and scanning electron microscopy analysis showed that the alloying elements were segregated in the deformed samples. The mechanical deformation determined both catalytic activity and corrosion resistance of the HEA. This study highlights the importance of considering corrosion resistance as a crucial factor in developing catalysts for green ammonia production. References [1] Energy Institute, “Statistical Review of World Energy 2023 | 72nd edition,” 2023. [2] B. R. Ryu, P. A. Duong, and H. Kang, “Comparative analysis of the thermodynamic performances of solid oxide fuel cell–gas turbine integrated systems for marine vessels using ammonia and hydrogen as fuels,” International Journal of Naval Architecture and Ocean Engineering, vol. 15, Jan. 2023, doi: 10.1016/j.ijnaoe.2023.100524. [3] B. S. Lou, I. Rahmadtulloh, C. J. Wang, W. H. Wang, and J. W. Lee, “Tribocorrosion behaviors of VNbMoTaWCr high entropy alloy coatings,” Surf Coat Technol, vol. 476, Jan. 2024, doi: 10.1016/j.surfcoat.2023.130250.

The motivation of this study is to promote sustainability in the construction and mining industries from a research perspective, considering the CO2 emissions associated with cement production and the use of mining waste materials, such as copper tailings, as supplementary cementitious materials. In this study, copper tailings partially replaced cement as received between 0 to 50 wt.%. Mortar and reinforced mortar samples were manufactured for mechanical and corrosion analysis. The mechanical tests revealed that the maximum compressive and flexion strengths were maintained by adding copper tailings, which were delayed for a longer exposure time, possibly due to the hydration reaction. Morphological analysis revealed that the partial cement replacement increased the porosity in the mortar at earlier stages, which was similar for longer exposure time. In addition, electrochemical impedance spectroscopy allowed in-situ monitoring of the mortar\'s evolution and mortar/steel interface. The impedance response showed that partial cement replacement with 15 wt. % of copper tailings as received can improve steel passivation after prolonged exposure. Therefore, cement replacements can be a suitable solution to produce reinforced mortars.

Cellulose and paper produce significant waste such as ash, activated sludge, and sludge from the pulp and paper industry. Depending on the raw material, legislation, and subprocesses, these sludges contain around 30–50% organic matter, mainly composed of less than 0.02 mm cellulose fibers and hemicellulose and lignin. This work used sludge from the pulp and paper industry as a substrate for manufacturing mycelium-based biomaterials using the white rot fungus Trametes versicolor. Chemical and surface analyses revealed the formation of new materials. Acoustic impedance analyses revealed that these materials have a noise reduction coefficient and sound absorption average comparable to extruded polystyrene and polyurethane. In addition, the material’s thermal conductivity was near that of sheep wool. Therefore, the biomaterials fabricated using sludge and Trametes versicolor have the potential to be a game-changer in the industry as promising thermoacoustic insulators.

Solid oxide fuel cells (SOFC) are a viable alternative for environmentally-friendly conversion of hydrogen into energy and multiphysics simulation can be used to diminish the experimental effort to improve their efficiency. However, an appropriate model of the involved processes and their parameters must be chosen. This paper studies the effects of choice between Maxwell-Stefan and Fick's law models, and uncertainty of electrode ionic conductivity sigma(ion) ion and anodic reference exchange current density i(0,ref,f), on cell performance as implemented in the COMSOL Multiphysics (R) software. In the case of Maxwell-Stefan, peak average power output increased by 21.9% as sigma(ion) varies from 10(-3) to 10(-1) S/cm, while the model based on Fick's law shows an increase of 55.2%. The Maxwell-Stefan model exhibits an increase in peak power of 6% as i(0,ref,f) ranges from 0.4 to 0.8 A/cm(2), and the Fick's law model an increase of 8.2%. The dependence of the Maxwell-Stefan model on sigma(ion) is characterized as logarithmic in the studied range. The Maxwell-Stefan model is deemed preferable because its lower sensitivity to the studied parameters helps mitigate uncertainty. It is concluded that despite its limitations, multiphysics modeling is a useful tool for directing research on SOFC materials owing to its descriptive potential.

The cement industry, responsible for 8% of global greenhouse gas emissions, necessitates developing sustainable materials to replace cement partially. This investigation examined the feasibility of using copper tailings, a byproduct of mining, as alternative materials for cement within mortars and reinforced mortars (0-15wt.%). The microstructural composition of the tailings was analyzed using scanning electron microscopy and X-ray diffraction. The corrosion resistance of mortars reinforced with copper tailings was elucidated through open-circuit potential measurements and electrochemical impedance spectroscopy. The results showed that incorporating 5 and 10wt.% of sieved copper tailings improved the mechanical strength and significantly enhanced the electrochemical stability, as indicated by more noble open-circuit potential values. Specifically, the sieved tailings played a crucial role in forming a more stable oxide film, which was confirmed by higher impedance values, suggesting a reduced corrosion rate. In contrast, mortars with 5wt.% of milled tailings exhibited properties like those of the control group. This electrochemical understanding highlights the potential of processed copper tailings in mitigating the environmental impact of cement production and enhancing the durability of cementitious composites.

Nickel aluminium bronze alloy specimens were produced using laser powder bed fusion (LPBF) and subjected to heat treatment to understand their corrosion behaviour when exposed to a 3.5 wt% NaCl solution. Electrochemical analysis, including impedance spectroscopy and polarization curves, was performed to characterize the samples after 30 days of immersion. The findings reveal that the as-built samples exhibit superior corrosion resistance compared to the heat-treated samples, primarily attributed to the lower presence of intermetallic phases, which hinder the alloy's passivation process.

Alumoxane film on anodized 2024 was obtained using stearic acid to prevent corrosion in a chloride medium. A cleaning pretreatment was applied to the metal surface to improve the adhesion and formation of the alumoxane film using three different sprays, ethanol, water, and NaOH. Then a molten stearic acid was applied to form an alumoxane. The obtained films were characterized by X-ray photoelectron spectroscopy and glow discharge optical emission spectroscopy, and electrochemical techniques, such as linear sweep voltammetry and electrochemical impedance spectroscopy, evaluated the corrosion protection. The surface analyses suggested an interaction between the boehmite and stearic acid to form alumoxane, and the electrochemical results revealed that alumoxane film using ethanol significantly improved the protection against corrosion due to the formation of compact and homogeneous films with a hydrophobic characteristic for the 2024-T3 alloy.

The motivation of this study is to promote sustainability in the construction and mining industries from a research perspective, considering the CO2 emissions associated with cement production and the use of waste materials as supplementary cementitious materials, such as copper tailings. In this study, cement was partially replaced by copper tailings as received at levels ranging from 15 wt.% to 50 wt.%. To assess the suitability of copper tailings as a supplementary cementitious material, the mortars were analyzed using compression and flexural tests, while the reinforced mortars were evaluated using electrochemical tests. The results revealed that the replacements delayed the hydration of the mortar, decreasing the mechanical strengths during the initial 14 days but reaching similar values after 21 days. Electrochemical impedance spectroscopy allowed in-situ monitoring of the mortar's morphological evolution, revealing the reinforced mortar's quality through high-frequency responses. Samples with partial cement replacement showed higher porosity responses than the control sample, which varied and became denser over time. Additionally, the impedance response showed that partial cement replacement with 15 wt. % of copper tailings improved the bar passivation process, particularly after prolonged exposure. Therefore, cement replacements can be a suitable solution to produce reinforced mortars.