Search Results (204)

Water scarcity poses a formidable challenge around the world, especially in arid regions where limited availability of freshwater resources threatens both human well-being and ecosystem sustainability. Membrane-based desalination technologies offer a viable solution to address this issue by providing access to clean water. This work ultimately aims to develop a novel permselective polymeric membrane material to be employed in an electrochemical desalination system. This part of the study addresses the optimization, preparation, and characterization of a polyvinylidene difluoride (PVDF) polymeric membrane using the electrospinning technique. The membranes produced in this work were fabricated under specific operational, environmental, and material parameters. Five different additives and nano-additives, i.e., graphene oxide (GO), carbon nanotubes (CNTs), zinc oxide (ZnO), activated carbon (AC), and a zeolitic imidazolate metal–organic framework (ZIF-8), were used to modify the functionality and selectivity of the prepared PVDF membranes. Each membrane was synthesized at two different levels of additive composition, i.e., 0.18 wt.% and 0.45 wt.% of the entire PVDF polymeric solution. The physiochemical properties of the prepared membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), zeta potential, contact angle, conductivity, porosity, and pore size distribution. Based on findings of this study, PVDF/GO membrane exhibited superior results, with an electrical conductivity of 5.611 mS/cm, an average pore size of 2.086 µm, and a surface charge of −38.33 mV. Full article

Point-of-care testing (POCT) offers a transformative approach to diagnostics by enabling rapid and accurate results at or near the site of patient care. This is especially valuable in critical care, emergency settings, and resource-limited areas. However, one major limitation of POCT remains its analytical sensitivity, particularly in detecting low concentrations of analytes. To address this, various innovations are being explored, including advanced sensors, signal amplification, and sensitive labels. Among these, bioluminescent proteins have gained attention for their high sensitivity, fast readout, minimal background interference, and simplified instrumentation. Bioluminescence—light emission from biochemical reactions—presents an ideal platform for enhancing POCT sensitivity. In parallel, metal–organic frameworks (MOFs), especially structures like ZIF-8, are emerging as valuable materials in biosensing. Their high porosity, tunable surface properties, and ability to host biomolecules make them excellent candidates for improving analyte capture and signal transduction. When integrated with bioluminescent systems, MOFs can stabilize proteins, concentrate targets, and enhance overall assay performance. This review highlights the role of bioluminescent proteins in medical diagnostics and their application in POCT platforms. We also discuss the potential synergy between MOFs and bioluminescence to overcome current sensitivity limitations. Finally, we examine existing challenges and strategies to optimize these technologies for robust, field-deployable diagnostic tools. By leveraging both the natural sensitivity of bioluminescence and the structural advantages of MOFs, next-generation POCT systems can achieve superior performance, driving forward diagnostic accessibility and patient care outcomes. Full article

Herein, we report on the synthesis of Ni and Zn clusters on the surface of TiO₂ as well as their bimetallic NiZn analogs. The materials were prepared by incipient wet impregnation of colloidal TiO₂ followed by microwave (MW) irradiation to graft the clusters to TiO₂ surface. The materials were further immobilized onto glass slides and exhibited high surface area, high mechanical stability, and porosity with accessible pores. The main species responsible for visible light degradation of microcystin LR via the interface charge transfer (IFCT) of excited e⁻ to surface metal clusters were found to be O₂^•− and h⁺. The optimal nominal grafting concentration was 0.5 wt.% for Ni and 1.0 wt.% for Zn, while for the bimetal modification (NiZn), the optimal nominal concentration was 0.5 wt.%. Compared to monometallic, bimetallic grafting showed a lower kinetic constant, albeit still improved compared to bare TiO₂. Bimetal-modified titania showed a lower photocurrent compared to single metal-grafted TiO₂ and poorer interfacial charge transport, namely, more recombination sites—possibly at the interface between the Ni and Zn domains. This work highlights the efficiency of using MW irradiation for grafting sub-nano-sized metallic species to TiO₂ in a homogeneous way. However, further strategies using MW irradiation for the structural design of bimetallic cocatalysts can be implemented in the future. Full article

The development of ultraflexible and sensitive gas sensors is critical for advancing next-generation environmental monitoring and healthcare diagnostics. In this work, we demonstrate an ultraflexible chemiresistive nitrogen dioxide (NO₂) sensor integrated with a photopatterned porous poly(3-hexylthiophene) (P3HT)/SU-8 blend film as an active sensing layer. The porous microarchitecture was fabricated via high-resolution photolithography, utilizing SU-8 as a photoactive porogen to template a uniform, interconnected pore network within the P3HT matrix. The engineered porosity level ranged from 0% to 36%, substantially improving gas diffusion kinetics to enlarge the accessible surface area for analyte adsorption. Our sensor exhibited a marked enhancement in sensitivity at an optimized porosity of 36%, with the current response at 30 ppm NO₂ increasing from 354% to 3201%, along with a detection limit of 0.7 ppb. The device further exhibited a high selectivity against common interfering gases, including NH₃, H₂S, and SO₂. Moreover, the porous structure imparted excellent mechanical durability, maintaining over 90% of its initial sensing performance after 500 bending cycles at a 1 mm radius, underscoring its potential for integration into next-generation wearable environmental monitoring platforms. Full article

Controlled porosity with precise pore sizes in carbon monoliths (CMs) is crucial for optimizing performance in electrochemical energy storage and adsorption applications. This study explores the influence of porosity in CMs, developed from polymer precursors via the sol–gel route, employing soft templating, in situ graphene growth, and post-activation. The effects on CO₂ and H₂ sorption and electrochemical capacitor (EC) performance are analyzed. Graphene is successfully grown in situ from graphene oxide (GO), as confirmed by several characterization analyses. The amount of GO incorporated influences the crosslink density of the polymer gel, generating various pore structures at both micro- and mesoscales, which impacts performance. For instance, CO₂ capture peaks at 5.01 mmol g⁻¹ (0 °C, 101 kPa) with 10 wt % GO, due to the presence of wider micropores that allow access to ultramicropores. For H₂ storage, the best performance is achieved with 5 wt % GO, reaching 12.8 mmol g⁻¹ (−196 °C, 101 kPa); this is attributed to the enlarged micropore volumes between 0.75 and 2 nm that are accessible by mesopores of 2 to 3 nm. In contrast, for the ECs, lower GO loadings (0.5 to 2 wt %) improve ion accessibility via mesopores (4 to 6 nm), enhancing rate capability through better conduction. Full article

Hierarchical porous carbon materials hold great potential for energy storage applications due to their high porosity, large specific surface area, and excellent electrical conductivity. Cellulose and sodium alginate are naturally abundant high-molecular-weight biopolymer materials. Utilizing them as precursors for the fabrication of high-performance electrochemical carbon materials is highly significant for achieving carbon neutrality goals. In this study, porous carbon aerogels were successfully synthesized using a combination of freeze-drying and a simple carbonization process, with nanocellulose and sodium alginate as precursors. Among the prepared samples, SC-0.03 (sodium alginate: nanocellulose = 0.1:0.03) exhibited the best performance, achieving a specific surface area of 713.7 m² g⁻¹. This material features an optimized hierarchical pore structure and a substantial intrinsic oxygen doping content, resulting in excellent capacitance performance. Benefiting from these structural advantages and their synergistic effects, the SC-0.03 electrode demonstrated a high specific capacitance of 251.5 F g⁻¹ at a current density of 0.5 A g⁻¹. This study shows that the construction of three-dimensional porous structures by taking advantage of the self-supporting properties of natural polymer materials does not require the introduction of external binders. Due to the nanoscale dimensions and high aspect ratio, nanocellulose enables the formation of a more refined and interconnected hierarchical pore network, enhancing ion accessibility and conductivity. The hierarchical porous carbon aerogel developed in this study, based on a biomass self-reinforcement strategy, not only shows great promise as an advanced energy storage material but also possesses environmentally friendly properties, offering new insights for the development of sustainable energy materials. Full article

The efficient mass transport and enhanced accessibility of active sites are crucial for high-performance electrocatalysts in water splitting. Inspired by the hierarchical structure of natural wood, we engineered a monolithic electrocatalyst, cobalt nanoparticles encapsulated in nitrogen-doped carbon layers on carbonized wood (Co@NC/CW), by carbonizing wood to create a three-dimensional framework with vertically aligned macropores. The unique architecture encapsulates cobalt nanoparticles within in situ-grown nitrogen-doped graphene layers on wood-derived microchannels, facilitating ultrafast electrolyte infusion and anisotropic electron transport. As a result, the optimized freestanding Co@NC/CW electrode exhibits remarkable bifunctional activity, achieving overpotentials of 403 mV and 227 mV for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively, at a current density of 50 mA cm⁻². Furthermore, the integrated hybrid electrolyzer combining the HER and the OER delivers an impressive 50 A cm⁻² at a cell voltage of 1.72 V while maintaining a Faradaic efficiency near 99.5% and sustaining long-term stability over 120 h of continuous operation. Co@NC/CW also demonstrates performance in the complete decomposition of alkaline seawater, underscoring its potential for scalable applications. This wood-derived catalyst design not only leverages the natural hierarchical porosity of wood but also offers a sustainable platform for advanced electrochemical systems. Full article

Concrete porosity is one of the fundamental properties for the structural characterization of cementitious materials. This study compares porosity data obtained with dynamic water vapor sorption (DWVS) with the more commonly used mercury intrusion porosimetry (MIP) method for a wide range of concrete samples made with basaltic aggregates, typical of the Canary Islands, which are porous. The objective was to propose an alternative method for routine concrete monitoring that avoids the use of a hazardous substance such as mercury. The results reveal fundamental differences between the MIP and water-accessible porosimetry (WAP) data, although a correlation between the methods was revealed where MIP = 1.18 × WAP. The study was completed by an analysis of the relationships between the porosity and the characteristics and properties of concrete (water/cement ratio and strength), as well as the calculation of the tortuosity factor and a frost durability factor. Full article

This paper presents three design case studies for implementing large-scale geologic carbon storage in the Appalachian Basin region of the midwestern United States. While the Appalachian Basin has a challenging setting for carbon storage, the three case studies detailed in this article demonstrate that there are realistic options for implementing carbon storage in the basin. Carbonate rock formations, depleted hydrocarbon reservoirs, and moderate-porosity sandstones can be utilized as carbon-storage reservoirs in the Appalachian Basin. While these are not typical concepts for CO₂ storage, the storage zones have advantages such as defined trapping mechanisms, multiple caprocks, and defined boundaries that are not always present in thick, permeable sandstones being targeted for many carbon-storage projects. The geologic setting, geotechnical parameters, and hydrologic setting for the three case studies are provided, along with the results of reservoir simulations of the CO₂ injection-deployment strategies. The geological rock formations available for CO₂ storage in the Appalachian Basin are more localized reservoirs with defined boundaries and finite storage capacities. Simulation results showed that accessing carbon-storage resources in these fields may require wellfields with 2–10 injection wells. However, these fields would have the capacity to inject 1–3 million metric tons of CO₂ per year and up to 90 million metric tons of CO₂ in total. The CO₂ storage resources would fulfill decarbonization goals for many of the natural-gas power plants, cement plants, hydrogen plants, and refineries in the Appalachian Basin region. Full article

Organic hybrid materials are gaining traction as electrode candidates for energy storage due to their structural tunability and environmental compatibility. This study investigates polyimide/carbon nanotube/polypyrrole (PI/CNTs/PPy) hybrid nanocomposites, focusing on the correlation between thermal imidization temperature, polypyrrole deposition time, and the resulting electrochemical properties. By modulating PI processing temperatures (90 °C, 180 °C, 250 °C) and PPy deposition durations (60–700 s), this research uncovers critical structure–function relationships governing charge storage behavior. Scanning electron microscopy and electrochemical impedance spectroscopy reveal that low-temperature imidization preserves porosity and enables ion-accessible pathways, while moderate PPy deposition enhances electrical conductivity without blocking pore networks. The optimized composite, processed at 90 °C with 60 s PPy deposition, demonstrates superior specific capacitance (850 F/g), high redox contribution (~70% of total charge), low charge transfer resistance, and enhanced energy/power density. In contrast, high-temperature processing and prolonged PPy deposition result in structural densification, increased resistance, and diminished performance. These findings highlight a synergistic design approach that leverages partial imidization and controlled doping to balance ionic diffusion, electron transport, and redox activity. The results provide a framework for developing scalable, high-performance, and sustainable electrode materials for next-generation lithium-ion batteries and supercapacitors. Full article

The production of hydrocarbon-based biofuels has been the target of intense research worldwide. In this context, the core goal of the present work was to investigate the use of mesopore-rich activated carbons (ACs) as support for sulfided Mo-based catalysts intended for the hydroprocessing of lipidic feedstocks. The key motivations for the work were that, in comparison to traditional inorganic supports such as Al₂O₃, ACs are less propense to form coke, due to their lower acidity, and are highly resistant to hydrolysis, which is a very important aspect in the hydroprocessing of lipidic feedstocks because water is abundantly produced during the process. Furthermore, the porosity of ACs can be tailored to give rise to a high mesopore content, which is important for improving the access of bulky triglyceride molecules to metallic active sites located inside the pores network. A systematic study on the effects of the preparation conditions on the properties and performance of the obtained catalysts was carried out for the first time. The highest hydrodeoxygenation (HDO) activity was verified for the catalyst prepared through sequential deposition of Mo and Ni by wet impregnation. The prepared catalyst presented better performance for coconut oil HDO than an industrial sulfided NiMo/Al₂O₃ catalyst. Furthermore, it presented good stability, provided that the sulfidation degree was kept high. The obtained results evidenced that ACs have great potential to replace inorganic support in sulfided Mo-based catalysts. Full article

This study investigates the effects of incorporating recycled coarse aggregates (RCAs) at different substitution rates on the mechanical and fracture properties of recycled aggregate concrete (RAC). Four concrete mixtures were prepared: a reference mixture using natural coarse aggregates (NCAs) and three RAC mixtures in which 30%, 60%, and 100% of the NCA mass was replaced with RCAs. The RAC mixtures were compared to natural aggregate concrete (NAC) in terms of compressive strength, splitting tensile strength, modulus of elasticity, hydration rate, water-accessible porosity, pore size distribution, post-peak behavior, and fracture energy. The results show that as the RCA substitution rate increases, the RAC porosity rises and its modulus of elasticity decreases. However, the compressive strength and splitting tensile strength remain comparable to, or even exceed, those of NAC, with optimal performance observed at a 60% substitution rate. This optimal behavior can be attributed to a more favorable pore distribution and an increased hydration rate. For an equivalent strength class, RAC with up to 60% RCA substitution exhibits post-peak behavior and fracture energy comparable to NAC. However, at a 100% substitution rate, the behavior becomes more brittle, and fracture energy decreases by 23.20%. Full article

Long-term human residence on the Moon is an inevitable trend in lunar exploration, necessitating the development of Bioregenerative Life Support Systems (BLSSs). In BLSSs, plant cultivation serves as the core functional unit, requiring substantial amounts of cultivation substrates. Lunar soil has potential as a cultivation substrate, but its suitability for plant growth must be improved to meet life-support requirements. As a fine-grained, organics-free, in situ resource, lunar soil’s high compaction significantly restricts crops’ root access to oxygen, water, and nutrients. While the addition of organic solid waste—a byproduct of BLSSs—could alleviate compaction, issues such as salinization, incomplete decomposition, and the presence of pathogens pose risks to crop health. In this study, we introduced earthworms into wheat cultivation systems to gradually digest, transfer (as vermicompost), and mix solid waste with a lunar soil simulant substrate. We set five experimental groups: a positive control group using vermiculite (named as V) as the optimal growth substrate, a negative control group using pure lunar soil simulant (LS), and three treatment groups using lunar soil simulant with solid waste and 15 (LS+15ew), 30 (LS+30ew), and 45 (LS+45ew) earthworms added. Our results demonstrated significant improvements in both compaction (e.g., bulk density, hydraulic conductivity) and salinization (e.g., salinity, electrical conductivity), likely due to the improved soil aggregate structures, which increased the porosity and ion adsorption capacity of the soil. Additionally, the microbial community within the substrate shifted toward a cooperative pattern dominated by significantly enriched plant probiotics. Consequently, the cultivated wheat achieved approximately 80% of the growth parameters (including production) compared to the control group grown in vermiculite with nutrient solution (representing ideal cultivation conditions), indicating sufficient nutrient supply from the mineralized waste. We can conclude that the earthworms “complementarily” improved the lunar soil simulant and organic waste by addressing compaction and salinization, respectively, leading to comprehensive improvements in key parameters, including the microbial environment. This study proposes a conceptual framework for improving lunar soil for crop cultivation, and it innovatively introduces earthworms as a preliminary yet effective solution. These findings provide a feasible and inspiring foundation for future lunar agriculture. Full article

The conservation tillage method is a more holistic method introduced in Hungary two decades ago. Its environmental benefits in agriculture were widely studied and documented. The impact of conservation tillage on soil compaction and penetration resistance remains debated, necessitating further research to clarify its long-term effects in different soil types and cropping systems. The present study evaluates the impact on soil penetration resistance following 16 years of implementation of six distinct tillage practices. The study was conducted at Józsefmajor Experimental and Training Farm (JM) of the Hungarian University of Agriculture and Life Sciences near Hatvan. The study employed a randomized complete block design (RCBD) to evaluate six distinct tillage methods. These methods encompassed disking (D) at 12–14 cm depth, shallow cultivation (SC) at 18–20 cm depth, no-tilling (NT), deep cultivation (DC) at 22–25 cm depth, loosening (L) at 40–45 cm depth, and plowing (P) at 28–30 cm depth. In this study, soil compaction was assessed by measuring soil penetration resistance (SPR) at different depths (0–50 cm) and periods of the cropping year. Disking and NT significantly increased SPR between 10 and 20 cm, likely due to increased soil densification and reduced porosity in the absence of deep soil disturbance. While under sunflower cropping season significantly higher SPR was measured. In March 2021, the SPR at D and NT differed significantly from other measurement dates (September, October, November, and April). Regarding the difference between the depths, SPR increased with increasing depths in all treatment plots. The study findings revealed that NT and D tillage methods significantly increased soil penetration resistance in both cropping years, whereas L and P reduced SPR and enhanced the soil moisture storage potential of the soil particularly for the sunflower cropping period. The significance of the Spearman correlations observed suggested that SPR could be a valuable indicator of root growth potential under certain tillage conditions. Based on our results, we recommend the adoption of occasional deep soil loosening for reduced tillage systems (SC, D, DC, and NT) for both wheat and sunflower. This will create a compact-free zone for greater crop root proliferation, nutrient access, and SMC storage. Full article

HKUST-1 (HKUST = Hong Kong University of Science and Technology) is one of the most recognized metal-organic frameworks (MOFs) based on copper and trimesate, extensively studied for a variety of applications, such as gas storage, separation, adsorption, electrocatalysis, drug delivery, sensor and photodegradation, etc. In this work, we introduce a novel nanofused HKUST-1, referred to as N-CuBTC (BTC = trimesate), which has been synthesized with the hydrothermal method at room temperature (typical synthesis temperature is from 80~120 °C). The resulting N-CuBTC features an irregular particle morphology, with numerous crystals clustering together and edges that have fused, creating a hierarchical pore structure. In contrast to the traditional micro-sized octahedral HKUST-1 (named as M-CuBTC), N-CuBTC displays a unique clumped morphology, where the HKUST-1 crystals are seamlessly integrated into a cohesive structure. This innovative formation significantly enhances mass transfer capabilities and porosity accessibility. Consequently, N-CuBTC demonstrates markedly improved catalytic performance in the cyanosilylation of aldehydes. Full article