Search Results (51)

Single-atom catalysts are highly efficient electrocatalysts for water splitting with exceptional atomic utilization, but atomic aggregation can impair their catalytic performance. To address this challenge, a Fe-Co-Ni single-atom bifunctional catalyst supported on nitrogen-doped graphene oxide was designed and employed for overall water splitting in alkaline electrolyte. The catalyst’s composition, structure, and morphology were systematically characterized using XRD, XPS, SEM, and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Electrochemical evaluations were performed to assess its activity and stability toward both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The results demonstrate that strong metal-nonmetal interactions between the Fe, Co and Ni single atoms and the nitrogen-doped graphene oxide support facilitate stable and uniform anchoring of the metal centers on the wrinkled carbon framework. The total metal loading reaches approximately 6.78 wt%, ensuring a high density of accessible active sites. Furthermore, synergistic electronic coupling among the Fe, Co, and Ni centers enhances charge transfer kinetics and modulates the D-band electronic states of the metal atoms. This effect weakens the adsorption strength of hydrogen and oxygen-containing intermediates, thus promoting faster reaction kinetics for both HER and OER. Consequently, the FeCoNi/CNG catalyst delivers low overpotentials of 77 mV for HER and 355 mV for OER at a current density of 10 mA cm⁻² in alkaline conditions. When integrated into an alkaline water electrolyzer, the system achieves a cell voltage of only 1.68 V to attain a current density of 10 mA cm⁻², underscoring its outstanding bifunctional catalytic performance. Full article

The operational failure of lithium-ion batteries under extreme temperatures (−40~60 °C) stems primarily from electrolyte limitations. While prior efforts improved either low-temperature or high-temperature performance independently, holistic electrolyte design with practical validation remains elusive. Herein, we develop an all-climate electrolyte (ACE) through synergistic coordination of solvent, Li salt, and additive, achieving low viscosity (<10 mPa·s at −40 °C) and high ionic conductivity (7.0 mS cm⁻¹ at −40 °C). Raman and NMR spectra reveal MA and EC co-occupying Li⁺ solvation sheath while EMC acts as a diluent, enabling rapid ion transport. Consequently, LiFePO₄ (LFP)|graphite (Gr) cell delivers unprecedented cyclability: zero capacity decay over 500 cycles at 0 °C, stable operation across −40~60 °C, and 94.1% retention after 100 cycles at 45 °C in Ah-level pouch cells. XPS and SEM analysis demonstrate lithium difluorophosphate (LiDFP) and lithium bis(fluorosulfonyl)imide (LiFSI) collaboratively remodel SEI/CEI interphases, enriching them with LiF, Li₃PO₄, and Li₂SO₄. This inorganic-dominant architecture enhances interfacial Li⁺ kinetics and all-climate stability compared to the baseline electrolyte. Our tripartite electrolyte strategy provides a material-agnostic solution for all-climate energy storage. Full article

Historically, clays have been widely used for the treatment of wounds and to stop hemorrhaging. The aim of this study was to combine four natural clay minerals (kaolinite, glauconite, montmorillonite, and bentonite) with magnetite (Fe₃O₄) nanoparticles to produce Fe₃O₄–clay complexes with enhanced antimicrobial properties and chemopreventive activity against melanoma. The magnetite–clay complexes were synthesized by the chemical co-precipitation method and characterized using XRD, TEM, STEM-EDS, SEM, and SQUID magnetometer. Antimicrobial properties were determined by evaluation of MIC values. The most promising materials were also subjected to direct contact antibacterial test according to the OECD standard for porous materials. Cytotoxicity of the complexes towards melanoma cells and normal human skin fibroblasts was assessed by MTT assay. We performed XRD, which confirmed the formation of Fe₃O₄–clay complex materials. It was also proven that complexes exhibited superparamagnetic properties. Microbiological experiments clearly revealed that modification of natural clays with magnetite significantly boosted their antimicrobial properties. Fe₃O₄–montmorillonite and Fe₃O₄–bentonite showed the strongest antimicrobial activity. Moreover, the mentioned complexes had the ability to reduce the viability of melanoma cells by 35–40%, while exhibiting no cytotoxicity against the normal human fibroblast (BJ) cell line, which is an extremely desirable feature. Thus, it may be concluded that Fe₃O₄–montmorillonite and Fe₃O₄–bentonite complexes hold promise for use in the management of infected wounds and wounds after melanoma excision. Full article

The electrochemical reduction in CO₂ (CO2RR) to syngas and value-added hydrocarbons offers a promising route for sustainable CO₂ utilization. This work develops tuneable Cu-Sn bimetallic catalysts via electrodeposition, optimized for CO2RR in a zero-gap flow cell fed with CO₂-saturated KHCO₃ solution, a configuration closer to industrial scalability than conventional H-cells. By varying electrodeposition parameters (pH, surfactant DTAB, and metal precursors), we engineered catalysts with distinct selectivity profiles: Cu-Sn(B), modified with DTAB, achieved 50% Faradaic efficiency (FE) to CO at −2.2 V and −50 mA·cm⁻², outperforming Ag-based systems that require higher overpotentials. Meanwhile, Cu-Sn(A) favoured C₂H₄ (35% FE at −100 mA·cm⁻²), and Cu-Sn(C) shifted selectivity to CH₄ (26% FE), demonstrating product tunability. The catalysts’ performance stems from synergistic Cu-Sn interactions and DTAB-induced morphological control, as revealed by SEM/EDX and electrochemical analysis. Notably, all systems operated at lower voltages than literature benchmarks while maintaining moderate CO₂ utilization (32–49% outlet). This study highlights the potential of electrodeposited Cu-Sn catalysts for energy-efficient CO2RR, bridging the gap between fundamental research and industrial application in syngas and hydrocarbon production. Full article

Solid oxide fuel cell (SOFC) systems often employ metallic cathode air pre-heaters (CAPHs), frequently made from alloys with high chromium (Cr) content, to recover thermal energy from exhaust gases and pre-heat incoming air and fuel. Cr evaporation from metallic CAPHs can poison SOFC cathodes, reducing their durability. To mitigate this, we investigated controlled pre-oxidation of a FeCrAl alloy (alloy 318) to form a protective alumina scale by self-growing, assessing its impact on and oxidation resistance and Cr retention capability for CAPH applications. The effects of pre-oxidation were investigated across a temperature range of 800 to 1100 °C and dwelling times of 0.5 to 4 h. The formed oxide scales were characterised using gravimetry in combination with advanced analytic techniques, such as SEM/EDX, STEM/EDX, TEM, and XRD. Subsequently, the pre-oxidised FeCrAl alloys were characterised with respect to the oxidation rate and Cr₂O₃ evaporation in a tubular furnace at 850 °C, with 6.0 L/min air flow and 3 vol% H₂O to simulate the SOFC cathode environment. TEM analysis confirmed that the FeCrAl alloys formed alumina scales with 10 nm and 34 nm thickness after 1 h of pre-oxidation at 900 and 1100 °C, respectively. The corrosion and Cr₂O₃ evaporation rates of the FeCrAl alloy at 850 °C in humidified air were shown to be dramatically decreased by pre-oxidation. It was found that the mechanisms of oxidation and Cr₂O₃ evaporation were found to be controlled by the formation of different alumina phases during the pre-oxidation. Measurements of Cr₂O₃ evaporation and weight gain revealed that the alloy 318 pre-treated at 1100 °C for 1 h will form an α-Al₂O₃ scale, leading to a 98% reduction of the oxidation rate and 90% reduction of Cr₂O₃ evaporation compared to the non-oxidised alloy 318 under simulated SOFC cathode conditions. Full article

Aircraft gas turbine blades operate in aggressive, generally oxidizing, atmospheres. A solution to mitigate the degradation and improve the performance of such components is the deposition of thermal barrier coatings systems (TBCs). High-velocity air fuel (HVAF) is a very efficient process for coating deposition in TBC systems, particularly for bond coats in aerospace applications. However, its low-temperature variant has received little attention in the literature and could be a promising alternative to limit oxidation during spraying when compared to conventional methods. This study has the main objective of analyzing how the geometry of the low-temperature HVAF gun influences the microstructure and the in-flight oxidation of MCrAlX coatings. To that end, a low-temperature HVAF torch is used to deposit MCrAlX coatings on a steel substrate with different nozzle lengths. In-flight particle diagnosis is used to measure the MCrAlX particle velocity, and to correlate to the nozzle geometry and to analyze its influence on the final coating. The microstructure of the coatings is assessed by scanning electron microscopy (SEM) and the material oxidation is analyzed and measured on a field emission scanning transmission electron microscope (FE-STEM) equipped with focused ion beam (FIB) and by Energy Dispersive Spectroscopy (EDS). Full article

The marine diatom genus Pseudo-nitzschia comprises cosmopolitan phytoplankton species commonly present in the Adriatic Sea. Species within the genus Pseudo-nitzschia have been of significant concern because they produce domoic acid (DA), which can cause amnesic shellfish poisoning (ASP). In this study, we identified Pseudo-nitzschia species along the Central and Southeastern Adriatic Sea, where monthly sampling carried out from February 2022 to February 2024 allowed for comprehensive species documentation. Pseudo-nitzschia species cell cultures isolated from the study areas were morphologically and molecularly analysed. Morphological analyses were performed using a scanning electron microscope (FE-SEM/STEM), while molecular analyses were conducted, targeting the ITS1-5.8S-ITS2, LSU, and rbcL regions, to confirm species identity. This integrative approach led to the identification of eight species: Pseudo-nitzschia allochrona, Pseudo-nitzschia calliantha, Pseudo-nitzschia delicatissima, Pseudo-nitzschia fraudulenta, Pseudo-nitzschia mannii, Pseudo-nitzschia multistriata, Pseudo-nitzschia pseudodelicatissima, and Pseudo-nitzschia subfraudulenta. Our findings underscore the value of a combined approach for reliable species identification and contribute to the development of genetic sequence databases that support the advancement of next-generation methods such as metabarcoding. This research emphasises the importance of combined morphological and molecular methods for the differentiation of the cryptic and pseudo-cryptic Pseudo-nitzschia species. Full article

This study presents the synthesis, characterization, and evaluation of hybrid hydrogels based on calcium alginate (Ca-Alg) and synthetic nanoclay LaponiteRD (Lap), with an emphasis on their swelling and sorption properties. The motivation behind the development of these hybrid hydrogels stems from the need for sustainable materials with enhanced mechanical strength, swelling properties, and sorption capacity for environmental remediation and controlled-release applications. Synthesis methods for the ionotropically cross-linked Ca-Alg hydrogel and Alg–Lap composite hydrogels, based on Alg and Lap in the form of granules and fibres, have been developed. The Fourier-transform infrared spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analyses of composite hydrogels confirmed the successful incorporation of Lap into the Ca-Alg matrix, indicating strong interactions between the polymer and clay, which enhanced the structural integrity of the hydrogels. The morphology of the surface and pore structure of nanocomposites were studied using Scanning Electron Microscopy (SEM). The swelling behaviour of the nanocomposites was largely dependent on the concentrations of Lap and the cross-linking agent (CaCl₂), with higher concentrations leading to more rigid, less swellable structures due to the increased cross-linking density. The sorption studies, specifically with Fe(II) ions, demonstrated that the hybrid hydrogels possess a large sorption capacity, with Lap contributing to selective sorption at lower Fe(II) ion concentrations and Alg enhancing overall capacity at higher concentrations. This suggests that the synergistic interaction between Alg and Lap not only improves mechanical stability but also tailors the sorption properties of the hydrogels. These findings position the Alg-Lap hydrogels as promising materials for a range of environmental applications, including wastewater treatment, heavy metal ion removal, and the design of advanced filtration systems. The study’s insights into the tunability of these hydrogels pave the way for further research into their use in diverse fields such as biomedicine, agriculture, and industrial water management. Full article

In this study, we investigated the spatial distribution and homogeneity of gold nanoparticles (AuNPs) on an alumina (Al₂O₃; AAO) substrate for potential application as surface-enhanced Raman scattering (SERS) sensors. The AuNPs were synthesized through thermal treatment at 450 °C at varying times (5, 15, 30, and 60 min), and their distribution was characterized using field-emission scanning electron microscopy (FE-SEM) and scanning transmission electron microscopy (STEM). The FE-SEM and STEM analyses revealed that the size and interparticle distance of the AuNPs were significantly influenced by the duration of thermal treatment, with shorter times promoting smaller and more closely spaced nanoparticles, and longer times resulting in larger and more dispersed particles. Raman spectroscopy, using Rhodamine 6G (R6G) as a probe molecule, was employed to evaluate the SERS enhancement provided by the AuNPs on the AAO substrate. Raman mapping (5 µm × 5 µm) was conducted on five sections of each sample, demonstrating improved homogeneity in the SERS effect across the substrate. The topological features of the AuNPs before and after R6G incubation were analyzed using atomic force microscopy (AFM), confirming the correlation between a decrease in surface roughness and an increase in R6G adsorption. The reproducibility of the SERS effect was quantified using the maximum intensity deviation (D), which was found to be below 20% for all samples, indicating good reproducibility. Among the tested conditions, the sample synthesized for 15 min exhibited the most favorable characteristics, with the smallest average nanoparticle size and interparticle distance, as well as the most consistent SERS enhancement. These findings suggest that AuNPs on AAO substrates, particularly those synthesized under the optimized condition of 15 min at 450 °C, are promising candidates for use in SERS-based sensors for detecting cancer biomarkers. This could be attributed to temperature propagation promoted at the time of synthesis. The results also provide insights into the influence of thermal treatment on the spatial distribution of AuNPs and their subsequent impact on SERS performance. Full article

Magnetic nanoparticles (MNPs) based on magnetite (Fe₃O₄) are attractive catalyst supports due to their high surface area, easy preparation, and facile separation, but they lack stability in acidic reaction media. The search for MNPs stable in oxidative acidic reaction media is a necessity if one wants to combine the advantages of MNPs as catalyst supports with those of iodine(III) reagents being environmentally benign oxidizers. In this work, immobilized iodophenyl organocatalysts on magnetite support (IMNPs) were obtained by crossed-linking polymerization of 4-iodostyrene with 1,4-divinylbenzene in the presence of MNPs. The obtained IMNPs were characterized by TGA, IR, SEM, STEM, and HAADF to gain information on catalyst morphology, average particle size (80–100 nm), and their core–shell structure. IMNP-catalysts tested in (i) the α-tosyloxylation of propiophenone 1 with meta-chloroperbenzoic acid (m-CPBA) and (ii) in the oxidation of 9,10-dimethoxyanthracene 3 with Oxone^® as the side-oxidant showed a similar performance as reactions using stoichiometric amounts of iodophenyl. The developed IMNPs withstand strong acidic conditions and serve as reusable organocatalysts. They are recyclable up to four times for repeated organocatalytic oxidations with rates of recovery of 80–92%. This is the first example of a—(4-iodophenyl)polystyrene shell—magnetite core-structured organocatalyst withstanding strong acidic reaction conditions. Full article

The imperative reduction of carbon dioxide into valuable fuels stands as a crucial step in the transition towards a more sustainable energy system. Perovskite oxides, with their high compositional and property adjustability, emerge as promising catalysts for this purpose, whether employed independently or as a supporting matrix for other active metals. In this study, an A-site-deficient La_0.9FeO₃ perovskite underwent surface decoration with Ni, Cu or Ni + Cu via a citric acid-templated wet impregnation method. Following extensive characterization through XRD, N₂ physisorption, H₂-TPR, SEM-EDX, HAADF STEM-EDX mapping, CO₂-TPD and XPS, the prepared powders underwent reduction under diluted H₂ to yield metallic nanoparticles (NPs). The prepared catalysts were then evaluated for CO₂ reduction in a CO₂/H₂ = 1/4 mixture. The deposition of Ni or Cu NPs on the perovskite support significantly enhanced the conversion of CO₂, achieving a 50% conversion rate at 500 °C, albeit resulting in only CO as the final product. Notably, the catalyst featuring Ni-Cu co-deposition outperformed in the intermediate temperature range, exhibiting high selectivity for CH₄ production around 350 °C. For this latter catalyst, a synergistic effect of the metal–support interaction was evidenced by H₂-TPR and CO₂-TPD experiments as well as a better nanoparticle dispersion. A remarkable stability in a 20 h time-span was also demonstrated for all catalysts, especially the one with Ni-Cu co-deposition. Full article

Polymers based on 2-(acetoacetoxy)ethyl methacrylate, charged with iron or sodium, were thermally heated at 150 °C. Both polymers were studied and characterized by SEM, TEM, STEM microscopy and SAEDF techniques. The morphological investigation revealed that, upon heating, both polymers were endowed with microholes, sometimes perfectly ordered, whose dimensions varied from 4–5 nm to approximately 500 nm. In the case of an Fe-containing copolymer, unexpectedly, iron did not fill in the cavities, thus implying that it was “dispersed” in the polymeric matrix. Electronic microdiffraction documented that both polymers exhibited a proto-crystallinity, likely induced by thermal heating. Full article

Background: Naturally derived sustainable biomaterials with high flexibility, mechanical properties, biocompatibility, and the ability to manipulate surface chemistry, providing a natural cellular environment, can be used for tissue engineering applications. However, only a few researchers have demonstrated the exploitation of natural architectures for constructing three-dimensional scaffolds. The chemical decellularization technique for fabricating natural scaffolds and their cytocompatibility assessment for tissue engineering applications need to be thoroughly explored and evaluated. Methods: Decellularization of natural scaffolds has been performed via a chemical method using anionic detergent sodium dodecyl sulfate (SDS) which was used for the in vitro culturing of murine embryonic NIH/3T3 fibroblasts. Techniques such as field-emission scanning electron microscopy (FE-SEM), compressive testing and swelling ratio, and biodegradation were performed to characterize the properties of fabricated decellularized natural scaffolds. Nucleic acid quantification, DAPI, and H&E staining were performed to confirm the removal of nuclear components. In vitro cytocompatibility and live/dead staining assays were performed to evaluate cultured fibroblasts’ metabolic activity and qualitative visualization. Results: 3D chitin/glucan- and cellulose-based scaffolds from edible mushroom (stem) (DMS) and unripe jujube fruit tissue (DUJF) were fabricated using the chemical decellularization technique. FE-SEM shows anisotropic microchannels of highly microporous structures for DMS and isotropic and uniformly arranged microporous structures with shallow cell cavities for DUJF. Both scaffolds exhibited good mechanical properties for skin tissue engineering and DUJF showed a higher compressive strength (200 kPa) than DMS (88.3 kPa). It was shown that the DUJF scaffold had a greater swelling capacity than the DMS scaffold under physiological conditions. At 28 days of incubation, DUJF and DMS displayed approximately 14.97 and 15.06% biodegradation, respectively. In addition, DUJF had greater compressive strength than DMS. Compared to DMS scaffolds, which had a compressive stress of 0.088 MPa at a 74.2% strain, the DUJF scaffolds had a greater compressive strength of 0.203 MPa at a 73.6% strain. The removal of nuclear DNA in the decellularized scaffolds was confirmed via nucleic acid quantification, DAPI, and H&E staining. Furthermore, both of these scaffolds showed good adherence, proliferation, and migration of fibroblasts. DMS showed better biocompatibility and high viability of cells than DUJF. Conclusions: This sustainable scaffold fabrication strategy is an alternative to conventional synthetic approaches for the in vitro 3D culture of mammalian cells for various tissue engineering and cultured meat applications. Full article

While the reverse water-gas shift (RWGS) reaction holds great promise as a method of converting CO₂ to CO and subsequently into valuable fuels, achieving its commercial viability requires the development of highly efficient, selective, durable, and low-cost catalysts. Recently, thin-film nanocatalysts produced through plasma deposition (PECVD) have garnered significant attention in this domain. Among them, FeOx-based catalytic films deposited using Fe(CO)₅ as a precursor, under reduced pressure (4–5 Pa) and a 13.56 MHz glow discharge, have demonstrated particular interest. Our study shows that by appropriately tuning the parameters of the plasma deposition process, it is feasible to generate nanocatalyst films exhibiting exceptional CO₂ conversion (38% at 673 K) and CO selectivity (97%). Moreover, the study has revealed the formation of a carbon deposit containing carbon nanotubes (CNTs) during the RWGS reaction, significantly increasing the catalytic activity of the films. Through an analysis involving X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and electron microscopy techniques (SEM and HRTEM), we have determined that CNTs not only serve as carriers for highly catalytically active Fe nanoparticles but also create nanoscale heterojunctions (p-n) with Fe₂O₃ nanoparticles, thereby enhancing their catalytic effect. This paper attempts to elucidate the differences and changes in the surface structure of FeOx-based films dictating the catalytic activity, which stems from both the conditions of plasma deposition and the environmental impact during the catalytic process. Full article

The development of visible-light-responsive (VLR) semiconductor materials for effective water oxidation is significant for a sustainable and better future. Among various candidates, bismuth tungstate (Bi₂WO₆; BWO) has attracted extensive attention because of many advantages, including efficient light-absorption ability, appropriate redox properties (for O₂ generation), adjustable morphology, low cost, and profitable chemical and optical characteristics. Accordingly, a facile solvothermal method has been proposed in this study to synthesize two-dimensional (2D) BWO nanoplates after considering the optimal preparation conditions (solvothermal reaction time: 10–40 h). To find the key factors of photocatalytic performance, various methods and techniques were used for samples’ characterization, including XRD, FE-SEM, STEM, TEM, HRTEM, BET-specific surface area measurements, UV/vis DRS, and PL spectroscopy, and photocatalytic activity was examined for water oxidation under UV and/or visible-light (vis) irradiation. Famous commercial photocatalyst–P25 was used as a reference sample. It was found that BWO crystals grew anisotropically along the {001} basal plane to form nanoplates, and all properties were controlled simultaneously by tuning the synthesis time. Interestingly, the most active sample (under both UV and vis), prepared during the 30 h solvothermal reaction at 433 K (BWO–30), was characterized by the smallest specific surface area and the largest crystals. Accordingly, it is proposed that improved crystallinity (which hindered charge carriers’ recombination, as confirmed by PL), efficient photoabsorption (using the smallest bandgap), and 2D mesoporous structure are responsible for the best photocatalytic performance of the BWO–30 sample. This report shows for the first time that 2D mesoporous BWO nanoplates might be successfully prepared through a facile template-free solvothermal approach. All the above-mentioned advantages suggest that nanostructured BWO is a prospective candidate for photocatalytic applications under natural solar irradiation. Full article