Search Results (2,762)

MXenes have emerged as promising candidates for energy storage and catalyst design. Through detailed density functional theory (DFT) calculations, we designed a series of new 2D composite MXene-based nanomaterials by covering excellent TM₃N₂ MXenes (TM = Nb, Ta, Mo, and W) with graphene or buckled silicene. Our findings demonstrate that this coating can lead to high catalytic activity for hydrogen evolution reactions (HER) in these composite MXene-based systems, with silicene exhibiting superior performance compared to graphene. The relevant carbon and silicon atoms in the coated materials serve as active sites for HER due to complex electron transfer processes. Additionally, doping N or P atoms into graphene/silicene, which have similar atomic radii, but larger electronegativity than C/Si atoms, can further enhance the HER activity of adjacent carbon or silicon atoms, thus endowing the composite systems with higher HER catalytic performance. Coupled with their high stability and metallic conductivity, all these composite systems show great potential as electrocatalysts for HER. These remarkable findings offer new strategies and valuable insights for designing non-precious and highly efficient MXene-based HER electrocatalysts. Full article

Hydrogen-centered electrochemical technologies play a vital role in sustainable energy conversion and storage. One of the challenges in achieving cheap hydrogen is to bridge the gap between advanced electrocatalysts and highly effective electrodes. The key lies in designing electrocatalysts with high intrinsic activity and understanding the structure–activity relationship in water electrolysis. Being proposed as promising electrocatalysts, bulk oxides, with their compositional and crystal structure flexibility, provide a good platform for studying the correlation between intrinsic activity and electronic structure and also for screening superior catalysts for water electrolysis. In this review, we discuss the recent developments of oxide electrocatalysts in understanding the structure–activity relationship. Firstly, we present a thorough overview of recent advances from both theoretical and experimental aspects. Subsequently, we highlight the design principles to provide guidance for promoting performance. Finally, the remaining challenges and perspectives about this field are presented. This review aims to provide guidance for the design of highly advanced oxide electrocatalysts for water electrolysis and large-scale green energy supply. Full article

Industrial trans and saturated fatty acids, which are key components of solid fats used in food products, should be replaced with unsaturated fatty acids from vegetable oils to reduce cardiovascular risk. However, unsaturated oils lack the structured networks required to replicate the technological properties of solid fats. Oleogelation, especially using polymer-based networks, offers a promising solution. This study optimized chitosan-based oleogels crosslinked with vanillin to mimic the texture of butter, partially hydrogenated fat, margarine, and palm fat while minimizing oil loss. Oleogels were prepared via the emulsion-template method and optimized through a central composite design combined with a desirability function, evaluating the effects of chitosan, vanillin, Tween^® 60 concentrations, oil type (canola or soybean), and storage temperature (4 °C or 25 °C). Optimized oleogels were characterized for their rheological and microstructural properties. Chitosan concentration primarily governed oil loss, hardness, and adhesiveness of oleogels, independent of the oil phase and storage temperature. However, storage at 4 °C reduced oil loss but increased the hardness and adhesiveness compared to storage at 25 °C. The highest desirability scores (0.72 to 0.94) were achieved in soybean oil oleogels with 0.99% chitosan, 0.24–0.32% vanillin, and 0.17–0.18% Tween^® 60, closely mimicking the texture of butter and margarine. These oleogels demonstrated stronger networks, enhanced gel strength, and elasticity, positioning them as viable alternatives to conventional solid fats. Full article

Aviation has become an essential part of the modern world’s ability to grow personal, market and international connections. To enable continued benefits while reducing emissions, future aircraft will need radical redesign and novel, complementary technologies. Hydrogen aircraft are potentially the means to emissions reduction. As part of the European Union’s (EU’s) Clean Aviation Joint Undertaking (CAJU), it is aimed to have hydrogen aircraft entering into service by 2035. To realise this, it would require the certification of these aircraft in a relatively short timeline, which the CONCERTO project aims to help enable. Given the lack of mature experimental designs and pending certification processes, this endeavour is ambitious. To accelerate this, dedicated preparation for the certification through regulatory analysis should be complete, requiring initial options for technologies and aircraft operations to be defined. The technologies and operations were defined, analysed and weighted in CONCERTO, upon which a Generic Concept was made, outlined in this paper, with Level 1 on the Certification Readiness Level Scale. The aircraft systems which are likely to experience the largest changes; Fuel Storage, Fuel Distribution, Propulsion, Auxiliary Power Unit (APU), Heat Exchange (HEX) System and Sensing and Monitoring for Hydrogen (H2), will be outlined in this paper with respect to their components and integration challenges, and the subsequent changes to operations to enable this. Full article

Ammonia is gaining increasing attention as a zero-carbon fuel and hydrogen carrier, offering high energy density, mature liquefaction infrastructure, and strong compatibility with existing energy systems. This review presents a comprehensive summary of the recent advances in ammonia-based clean energy systems. It covers the fuel’s physicochemical properties, green synthesis pathways, storage and transport technologies, combustion behavior, NO_X formation mechanisms, emission control strategies, and safety considerations. Co-firing approaches with hydrogen, methane, coal, and DME are evaluated to address ammonia’s low reactivity and narrow flammability limits. This paper further reviews engineering applications across power generation, maritime propulsion, and long-duration energy storage, drawing insights from current demonstration projects. Key technical barriers—including ignition delay, NO_X emissions, ammonia slip, and economic feasibility—are critically examined. Finally, future development trends are discussed, highlighting the importance of integrated system design, low-NO_X combustor development, solid-state storage materials, and supportive policy frameworks. Ammonia is expected to serve as a strategic energy vector bridging green hydrogen production with zero-carbon end-use, facilitating the transition to a sustainable, secure, and flexible energy future. Full article

Hydrogen is an alternative energy source for the aviation industry due to its renewability and cleanliness, although this novel application needs to be reassessed for the potential leakage risk. For this reason, we take a small hydrogen-powered aircraft as the research object and investigate hydrogen diffusion behavior in the cabin after 35 MPa onboard hydrogen storage system leakage. Firstly, the effectiveness of the numerical simulation model is verified. Secondly, the numerical simulation model is utilized to simulate the changes in hydrogen mole fraction in the cabin under various scenario conditions (different leakage diameters, directions, and environment parameters). Finally, we investigate the impact of ventilation. Forced ventilation could significantly reduce the hydrogen mole fraction in the cabin in a short time. However, forced ventilation also promotes the diffusion of residual hydrogen in the cabin, resulting in a large proportion of the volume having a hydrogen mole fraction greater than 0.04, but it can significantly reduce the proportion of high hydrogen mole fraction (>0.1 or >0.2) regions. Full article

As the presence of renewable energy production grows, so does the need to find alternative solutions for long–term energy storage. One solution may be hydrogen, and more generally, power-to-gas systems, which could allow energy storage for longer periods than batteries. However, the problem of hydrogen storage remains a limitation to the deployment of this technology. A possible solution for the hydrogen storage could be metal hydrides. In this work, a power-to-gas system based on a $2.5\mathrm{kW}$ commercial electrolyzer coupled to a pair of AB2-type metal hydride cylinders with a total volume of $4\mathrm{L}$ is studied. A special focus is placed on the electrolyzer power converter. In particular, the current ripple generated on the side connected to the stack and the efficiency of the converter are studied. A series of tests are carried out to verify the behavior of the system with varying types of thermal conditioning of the hydrides. The results show that the converter used is not optimized for the chosen application, and the thermal conditioning influences the hydrogen adsorption rate and thus the electrolyzer’s behavior. Finally, a technique to operate the system at maximum efficiency is proposed. Full article

Multi-source systems are gaining attention as an effective approach to seamlessly incorporate renewable energies within electrical networks. These systems offer greater flexibility and better energy management possibilities. The considered multi-source system is based on a 50 MW wind farm connected to battery energy storage and electrolyzers through modular multi-level DC/DC converters. Wind energy systems interface with the DC-bus via rectifier power electronics that regulate the DC-bus voltage and implement optimal power extraction algorithms for efficient wind turbine operation. However, integrating intermittent renewable energy sources with optimal microgrid management poses significant challenges. It is essential to mention that the studied multi-source system is connected to the DC loads (modular electrolyzers and local load). This work proposes a new regulation method designed specifically to improve the performance of the system. In this strategy, the excess wind farm energy is converted into hydrogen gas and may be stored in the batteries. On the other hand, when the wind speed is low or there is no excess of energy, electrolyzer operations are stopped. The battery energy management depends on the power balance between the DC load (modular electrolyzers and local load) requirements and the energy produced from the wind farm. This control should lead to eliminating the fluctuations in energy production and should have a high dynamic performance. This work presents a nonlinear control method using a backstepping concept to improve the performances of the system operations and to achieve the mentioned goals. To evaluate the developed control strategy, some simulations based on real meteorological wind speed data using Matlab are conducted. The simulation results show that the proposed backstepping control strategy is satisfactory. Indeed, by integrating this control strategy into the multi-source system, we offer a flexible solution for battery and electrolyzer applications, contributing to the transition to a cleaner, more resilient energy system. This methodology offers intelligent and efficient energy management. Full article

The aim of this study is to investigate a green and efficient hydrothermal synthesis method for obtaining a high-purity MIL-100(Fe) metal–organic framework (MOF) without using hazardous HF acid or other toxic reagents. The influence of various synthesis conditions (reactant ratios and reaction times) and washing protocols on the MOF’s properties and crystallinity was investigated. Additionally, the adsorption capacities of the synthesized MIL-100(Fe) for hydrogen (H₂), carbon dioxide (CO₂), and water vapor were evaluated at different temperatures and pressures. By analyzing the adsorption behavior, this research study aims to assess the potential of this material for thermal or specific gas storage applications. MF-S1 synthesis, using less iron and water, produces the purest MIL-100(Fe), as confirmed by XRD and FTIR. MF-S1-W2, with additional washing, is ideal for gas adsorption due to its crystallinity, purity, and high surface area. It effectively stores hydrogen (0.25 wt.% at 5 °C), CO₂ (32.6 wt.% at 5 °C), and water vapor (47.5 wt.% at 30 °C). Full article

As health concerns and regulatory pressures over saturated and trans fats grow, there is a growing need for healthier alternatives to traditional solid fats, such as butter and hydrogenated oils, that are still widely used in the food system. In this study, cellulose particle-based Pickering emulsions (CP-PEs) were prepared from microcrystalline cellulose and ethylcellulose and then foamed to obtain edible oleofoams (CP-EOs) as a solid-fat replacer. The average size of CP-PE droplets without surfactant was 598 ± 69 nm, as confirmed by confocal and transmission electron microscopy. Foaming with citric acid/NaHCO₃ and structuring with ≥6% glyceryl monostearate resulted in CP-EOs with an overrun of 147 ± 4% and volumetric stability for 72 h. Micro-computed tomography showed a uniform microcellular network, while the rheological analysis showed solid-like behavior with a storage modulus higher than butter. Differential scanning calorimetry showed a melting enthalpy similar to unsalted butter (10.1 ± 0.9 J/g). These physicochemical properties demonstrate that CP-EOs can closely mimic the firmness, thermal profile, and mouth-feel of conventional solid fats and may provide a promising solid-fat replacer. Full article

Due to environmental concerns and increasing energy needs, hydrogen is increasingly seen as a promising alternative to fossil fuels. Its advantages include minimal greenhouse gas emissions (depending on origin), high efficiency, and widespread availability. Various storage methods have been developed, with high-pressure storage being currently among the most common due to its cost-effectiveness and simplicity. Composite high-pressure vessels are categorized as type III or IV, with type III using an aluminum alloy liner and type IV utilizing a polymer liner. This paper investigates damage mechanisms in filament wound carbon fiber composite pressure vessels subjected to low-velocity impacts, focusing on two types of impactors (with different geometries) with varying impact energies. The initial section features experimental trials that capture various failure modes (e.g., matrix damage, delamination, and fiber breakage) and how different impactor geometries influence the damage mechanisms of composite vessels. A numerical model was developed and validated with experimental data to support the experimental findings, ensuring accurate damage mechanism simulation. The research then analyzes how the shape and size of impactors influence damage patterns in the curved vessel, aiming to establish a relationship between impactor geometry features and damage, which is crucial for the design and applications of carbon fiber composites in such an engineering application. Full article

MoS₂ has emerged as a highly promising catalyst for the hydrogen evolution reaction (HER) owing to its exceptional catalytic properties. However, there is a pressing need to further enhance its reactivity and integrate oxygen evolution reaction (OER) capabilities to facilitate its industrial implementation. In this context, a dual-metal doping approach presents a straightforward and effective strategy to achieve superior catalytic performance. Systematic characterization and electrochemical evaluations reveal that the synergistic effects of Co and Fe doping significantly enhance both HER and OER activities, demonstrating remarkable potential for practical applications in energy conversion and storage systems. The unique flower-like architecture of the material endows it with a substantially enlarged surface area, which significantly increases the exposure of active sites and facilitates enhanced catalytic activity. Specifically, it achieves the low overpotentials of −127 and 292 mV at 10 mA cm⁻² for HER and OER in alkaline media, respectively, and demonstrates excellent stability over a 10 h test. This research provides valuable insights into the development of advanced materials capable of efficiently performing both HER and OER processes, paving the way for potential applications in sustainable energy technologies. Full article

Magnesium-based alloys, known for their high hydrogen storage capacity, suffer from sluggish kinetics and high activation energy barriers. It can be further optimized through synergistic combinations with metal hydrides. This study aims to address these limitations by investigating the hydrogen sorption properties of AZ31 magnesium alloy combined with different compositions of WS2 nanotubes (NTs) and Pd. The materials AZ31, WS2 (tungsten disulfide) NTs, and Pd were pre-processed via the mechanical ball milling process. Field emission-scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were employed to investigate the composite morphology and confirm the nanotubular structure of WS₂. This work is among the first to explore the synergistic catalytic effects of WS₂ nanotubes and Pd on the hydrogenation/dehydrogenation behavior of AZ31 alloys. The composite with 8 wt.% WS₂ NT/Pd demonstrated the fastest hydrogen sorption kinetics and a significant reduction in activation energy, from 123.25 kJ/mol to 104.58 kJ/mol. These results highlight the enhanced dehydrogenation performance of AZ31 through catalyst inclusion, offering a promising approach to improve hydrogen storage materials. These findings highlight the potential of combining inorganic NTs and transition metals as effective catalysts to enhance the hydrogen storage performance. This research paves the way for developing advanced hydrogen storage materials with improved performance, contributing to a sustainable energy future. Full article

Graphyne, a hypothetical carbon allotrope comprising sp and sp² hybridized carbon atoms, has garnered significant attention for its potential applications in next-generation technologies. Unlike graphene, graphyne’s distinctive acetylenic linkages endow it with a tunable electronic structure, directional charge transport, and superior mechanical flexibility. This review delves into the structural variety, theoretical underpinnings, and burgeoning experimental endeavors associated with various graphyne allotropes, including α-, β-, γ-, and 6,6,12-graphyne. It examines synthesis methods, structural and electronic characteristics, and the material’s prospective roles in diverse fields, such as nanoelectronics, transistors, hydrogen storage, and desalination. Additionally, it highlights the use of computational modeling techniques—density functional theory (DFT), GW approximation, and nonequilibrium Green’s function (NEGF)—to anticipate and validate properties without fully scalable experimental data. Despite substantial theoretical progress, the practical implementation of graphyne-based devices faces several challenges. By critically assessing current research and identifying strategic directions, this review underscores graphyne’s potential to revolutionize advanced materials science. Full article

The sustainable valorization of lignocellulosic biomass into high-value platform chemicals presents a crucial pathway for reducing reliance on fossil resources. Gamma (γ)-valerolactone (GVL) has gained recognition as a versatile bio-derived compound with broad applications in renewable energy systems and green chemical synthesis. While conventional GVL production strategies from carbohydrate biomass typically depend on noble metal catalysts paired with high-pressure hydrogen gas, these approaches face substantial technical barriers including catalyst costs, hydrogen storage requirements, and operational safety concerns in large-scale applications. This work develops an innovative catalytic system utilizing earth-abundant iron for in situ hydrogen generation through water splitting, integrated with Raney Ni as the hydrogenation catalyst. The designed two-stage process enables direct conversion of cellulose—first through acid hydrolysis to levulinic acid (LA) followed by catalytic hydrogenation to GVL without intermediate purification. Through systematic parameter optimization, a remarkable 61.9% overall GVL yield from cellulose feedstock was achieved. Furthermore, the methodology’s versatility was demonstrated through wheat straw conversion experiments, yielding 24.6% GVL. This integrated methodology explores a technically feasible pathway for direct cellulose-to-GVL conversion utilizing abundant water as the hydrogen source, effectively overcoming the critical limitations associated with conventional hydrogenation technologies regarding hydrogen infrastructure and process safety. Full article