Search Results (11,007)

Polyaniline (PANI), characterized by its proton-coupled redox mechanism and multicolor reversibility, is widely investigated for adaptive optical interfaces. Compared to inorganic oxides, PANI offers advantages in cost-effectiveness, mechanical flexibility, and molecular tunability; however, its practical implementation faces challenges related to kinetic limitations and environmental instability. This review presents a comprehensive analysis of PANI-based electrochromic materials, examining the intrinsic correlations among synthesis methodologies, microstructural characteristics, and optoelectronic performance. Synthesis strategies, including chemical oxidative polymerization, electrochemical deposition, and template-assisted techniques, are evaluated. Emphasis is placed on resolving the trade-off between optical contrast and switching kinetics by constructing high-surface-area porous nanostructures and inducing chain ordering via functional dopants to shorten ion diffusion paths and reduce charge transfer resistance. Fundamental electrochromic properties are subsequently discussed, with specific attention to degradation mechanisms triggered by environmental factors, such as pH drift, and stabilization strategies involving electrolyte engineering and composite design. Furthermore, the review addresses the evolution of applications from single-band monochromatic displays to dual-band smart windows for decoupled visible/near-infrared regulation and multifunctional integrated systems, including electrochromic supercapacitors and adaptive thermal management textiles. Finally, technical challenges regarding long-term durability, neutral color development, and large-area manufacturing are summarized to outline future research directions for PANI-based optical systems. Full article

Thorium carbide (ThC${}_{2\pm x}$) nano-structured thin disc-like pellets were produced from thoria nanoparticles (ThO${}_2$-NP) and multi-walled carbon nanotubes (MWCNT). These composites are to be studied as a target material candidate for radioactive ion beam (RIB) production via nuclear reactions upon impact with high-energy proton beams on a stack of solid pellets. The ThO${}_2$-NP precursor was produced via precipitation of thorium oxalate from a thorium nitrate solution with oxalic acid and subsequent hydrothermal oxidation of the oxalate, creating the thoria nanoparticles. The ThO${}_2$-NP were then mixed with MWCNT in isopropyl alcohol and sonicated by two different methods to create a nanoparticle dispersion. This dispersion was then heated under medium vacuum to evaporate the solvent; the resulting powder was pressed into pellets and taken to an inert-atmosphere oven, where it was heated to 1650 ${}^{\circ }$C and carbothermally reduced to ThC${}_{2\pm x}$. The resulting pellets were characterized via XRD, SEM-EDS, and Raman spectroscopy. The resulting thorium pellets exhibited, at most, trace levels of the oxide precursor. Furthermore, the nanotube structures were still present in the final product and are expected to contribute positively towards faster radioisotope release times by lowering isotope diffusion times, which is required for the efficient extraction of the shortest-lived (<1 s half-life) radioisotopes. Full article

One-dimensional ZnO nanowires offer significant potential for optoelectronic applications, though their controlled synthesis remains challenging. This study optimized ZnO nanowire growth via carbothermal reduction vapor transport based on the vapor–liquid–solid mechanism. Key parameters investigated were gold catalyst thickness and annealing, source temperature, system pressure, and oxygen concentration. Results show that thinner Au films promote high-density, small-diameter nanowires. An optimal source temperature window (950–1000 °C) was identified, while pressure and oxygen content critically influenced growth mode by modulating vapor supersaturation. Under optimized conditions, aligned single-crystalline ZnO nanowires with hexagonal wurtzite structure were achieved. Structural and optical characterization confirmed high crystallinity and strong near-band-edge emission, demonstrating the efficacy of the developed approach for tailored nanowire synthesis. Full article

Alkaline water electrolysis remains one of the leading and most mature technologies for large-scale hydrogen production. Its advantages stem from the use of inexpensive, earth-abundant materials and well-established industrial deployment, yet the technology continues to face challenges, including sluggish hydrogen evolution reaction (HER) kinetics and energy-efficiency limitations compared with acidic electrolysis systems. This review provides a comprehensive overview of the fundamental principles governing alkaline electrolysis, encompassing electrolyte chemistry, electrode materials, electrochemical mechanisms, and the roles of overpotentials, cell resistances, and surface morphology in determining system performance. Key developments in catalytic materials are discussed, highlighting both noble-metal and non-noble-metal electrocatalysts, as well as advanced approaches to surface modification and nanostructuring designed to enhance catalytic activity and long-term stability. Particular emphasis is placed on the emerging strategy of in situ ionic activation, wherein transition-metal ions and oxyanions are introduced directly into the operating electrolyte. These species dynamically interact with electrode surfaces under polarization, inducing real-time surface reconstruction, improving water dissociation kinetics, tuning hydrogen adsorption energies, and extending electrode durability. Results derived from polarization measurements, electrochemical impedance spectroscopy, and surface morphology analyses consistently demonstrate that ionic activators, such as Ni–Co–Mo systems, significantly increase the HER performance through substantial increase in surface roughness and increased intrinsic electrocatalytic activity through synergy of d-metals. By integrating both historical context and recent research findings, this review underscores the potential of ionic activation as a scalable and cost-effective way toward improving the efficiency of alkaline water electrolysis and accelerating progress toward sustainable, large-scale green hydrogen production. Full article

As a potential strategic resource of critical metals, deep-sea cobalt-rich crusts represent one of the most promising metal reservoirs within oceanic seamount systems, and their metallogenic mechanism constitutes a frontier topic in deep-sea geoscience research. This review focuses on the cobalt-rich crusts from the Magellan Seamount region in the northwestern Pacific and synthesizes existing geological, mineralogical, and geochemical studies to systematically elucidate their mineralization processes and metal enrichment mechanisms from a microstructural perspective, with particular emphasis on cobalt enrichment and its controlling factors. Based on published observations and experimental evidence, the formation of cobalt-rich crusts is divided into three stages: (1) Mn/Fe colloid formation—At the chemical interface between oxygen-rich bottom water and the oxygen minimum zone (OMZ), Mn²⁺ and Fe²⁺ are oxidized to form hydrated oxide colloids such as δ-MnO₂ and Fe(OH)₃. (2) Key metal adsorption—Colloidal particles adsorb metal ions such as Co²⁺, Ni²⁺, and Cu²⁺ through surface complexation and oxidation–substitution reactions, among which Co²⁺ is further oxidized to Co³⁺ and stably incorporated into MnO₆ octahedral vacancies. (3) Colloid deposition and mineralization—Mn–Fe colloids aggregate, dehydrate, and cement on the exposed seamount bedrock surface to form layered cobalt-rich crusts. This process is dominated by the Fe/Mn redox cycle, representing a continuous evolution from colloidal reactions to solid-phase mineral formation. Biological processes play a crucial catalytic role in the microstructural evolution of the crusts. Mn-oxidizing bacteria and extracellular polymeric substances (EPS) accelerate Mn oxidation, regulate mineral-oriented growth, and enhance particle cementation, thereby significantly improving the oxidation and adsorption efficiency of metal ions. Tectonic and paleoceanographic evolution, seamount topography, and the circulation of Antarctic Bottom Water jointly control the metallogenic environment and metal sources, while crystal defects, redox gradients, and biological activity collectively drive metal enrichment. This review establishes a conceptual framework of a multi-level metallogenic model linking macroscopic oceanic circulation and geological evolution with microscopic chemical and biological processes, providing a theoretical basis for the exploration, prediction, and sustainable development of potential cobalt-rich crust deposits. Full article

Plasmonics and metasurfaces (MSs) have emerged as two of the most influential platforms for manipulating light at the nanoscale, each offering complementary strengths that challenge the limits of conventional optical design. Plasmonics enables extreme subwavelength field confinement, ultrafast light–matter interaction, and strong optical nonlinearities, while MSs provide versatile and compact control over phase, amplitude, polarization, and dispersion through planar, nanostructured interfaces. Recent advances in materials, nanofabrication, and device engineering are increasingly enabling these technologies to be combined within unified planar and hybrid optical platforms. This review surveys the physical principles, material strategies, and device architectures that underpin plasmonic, MS, and hybrid plasmonic–dielectric systems, with an emphasis on interface-mediated optical functionality rather than long-range guided-wave propagation. Key developments in modulators, detectors, nanolasers, metalenses, beam steering devices, and programmable optical surfaces are discussed, highlighting how hybrid designs can leverage strong field localization alongside low-loss wavefront control. System-level challenges including optical loss, thermal management, dispersion engineering, and large-area fabrication are critically examined. Looking forward, plasmonic and MS technologies are poised to define a new generation of flat, multifunctional, and programmable optical systems. Applications spanning imaging, sensing, communications, augmented and virtual reality, and optical information processing illustrate the transformative potential of these platforms. By consolidating recent progress and outlining future directions, this review provides a coherent perspective on how plasmonics and MSs are reshaping the design space of next-generation planar optical hardware. Full article

This work investigates the feasibility of synthesis hybrid x Gd₂O₃ + (100 − x) Fe₃O₄ nanoparticles using the scalable method of high-energy ball milling for dual-contrast magnetic resonance imaging applications. Comprehensive studies of the structure, magnetic and functional properties of the hybrid nanoparticles were conducted. It was found that the milling process initiates the transformation of the cubic phase c-Gd₂O₃ ($\mathrm{I}\mathrm{a}\overline{3}$) into the monoclinic m-Gd₂O₃ (C2/m). Measurements of the magnetic properties showed that the specific saturation magnetization of the Fe₃O₄ phase is substantially reduced, which is a characteristic feature of nanoparticles due to phenomena such as surface spin disorder and spin-canting effects. The transmission electron microscopy results confirm the formation of hybrid Fe₃O₄-Gd₂O₃ nanostructures and the measured particle sizes show good correlation with the X-ray diffraction results. A comprehensive structure–property relationship study revealed that the obtained hybrid nanoparticles exhibit high r₂ values, reaching 160 mM⁻¹s⁻¹ and low r₁ values, a characteristic that is determined primarily by the presence of a large fraction of Gd₂O₃ particles with sizes of ≈30 nm and Fe₃O₄ crystallites of ≈10 nm. Full article

Electrolyte degradation and trace water contamination critically affect the lifetime and safety of lithium-ion batteries. In organic-based electrolytes such as acetonitrile (MeCN), even small amounts of water can trigger ${\mathrm{PF}}_6^{-}$ hydrolysis, producing HF, POF₃, and related species that contribute to electrolyte ageing and alter interfacial reactions. This study explores the electrochemical signatures of ageing and moisture contamination in Bu₄NPF₆- and LiPF₆-based MeCN electrolytes through a systematic cyclic voltammetry protocol. Platinum electrodes with different surface morphologies—flat, Nafion-coated, and nanostructured—were compared to assess their sensitivity to water-induced degradation. Cathodic Faradaic currents appearing around −0.7 to −1.0 V vs. Ag/AgCl were attributed to the protonic species generated by ${\mathrm{PF}}_6^{-}$-induced hydrolysis. The presence of LiPF₆, commonly used in battery electrolytes, further increases the concentration of anions responsible for the protonic species, therefore contributing to the acceleration of the electrolyte degradation. Experiments using a Nafion proton-conductive membrane assess the protonic origin of these peaks. Meanwhile, nanostructured platinum exhibits approximately four times higher current responses and enhanced sensitivity to water additions, reflecting the influence of surface roughness and active area. Overall, the findings indicate that electrode morphology significantly influences the detectability of ageing- and water-driven reactions, supporting the potential of nanostructured Pt as a diagnostic material for in situ monitoring. Full article

Machine learning (ML) is increasingly used to address the computational complexity and multiscale nature of mechanical analysis in nanomaterials and nanostructures. Traditional analytical, numerical, and atomistic approaches, such as continuum mechanics, finite element methods, and molecular dynamics (MD), often suffer from high computational cost or limited scalability when applied to nanoscale systems. Recently, ML techniques have been increasingly used to predict mechanical properties, analyze static and dynamic responses, and solve governing equations of nanostructures to improve efficiency and accuracy. This review provides a comprehensive overview of ML applications in the mechanical analysis of nanomaterials and nanostructures, including mechanical property prediction, static response analysis, and vibration analysis. Various ML techniques based on the property or type of the mechanical problem are discussed in detail. The review highlights current trends and provides structured guidance for future research on reliable and physically consistent ML methods for nanoscale mechanical analysis. Full article

Organic optoelectronic devices receive appreciable attention due to their low cost, ecology, mechanical flexibility, band-gap engineering, brightness, and solution process ability over a broad area. In this study, we designed and studied organic light-emitting diodes (OLEDs) consisting of an assembly of natural dyes, extracted from noble fir leaves (evergreen) and blue hydrangea flowers mixed with poly-methyl methacrylate (PMMA) as light emitters. We experimentally demonstrate the effective conversion of blue light emitted by an inorganic laser/photodiode into longer-wavelength red and green tunable photoluminescence due to the excitation of natural dye–PMMA nanostructures. UV-visible absorption and photoluminescence spectroscopy, ellipsometry, and Fourier transform infrared methods, together with optical microscopy, were performed for confirming and characterizing the properties of light-emitting diodes based on natural dyes. We highlighted the optical and physical properties of two different natural dyes and demonstrated how such characteristics can be exploited to make efficient LED devices. A strong pure red emission with a narrow full-width at half maximum (FWHM) of 23 nm in the noble fir dye–PMMA layer and a green emission with a FWHM of 45 nm in blue hydrangea dye–PMMA layer were observed. It was revealed that adding monolayer MoS₂ to the nanostructures can significantly enhance the photoluminescence of the natural dye due to a strong correlation between the emission bands of the inorganic–organic emitters and back mirror reflection of the excitation blue light from the monolayer. Based on the investigation of two natural dyes, we demonstrated viable pathways for scalable manufacturing of efficient hybrid OLEDs consisting of assembly of natural-dye polymers through low-cost, purely ecological, and convenient processes. Full article

Background: Nanotechnology provides innovative strategies to enhance drug delivery and therapeutic efficacy through advanced nanocarrier systems. Objectives: This study aimed to develop and optimize a nanostructured lipid carrier (NLC) co-encapsulating curcumin (CUR) and resveratrol (RESV) using a fractional factorial design to develop a topical formulation with antioxidant and anti-inflammatory properties. Methods: NLCs were produced via hot emulsification followed by high-pressure homogenization, and their physicochemical characteristics, drug content, stability, release profile, antioxidant activity, skin delivery, and cellular compatibility were evaluated. Results: The optimized formulation exhibited an average particle size of approximately 300 nm, a polydispersity index below 0.3, and high drug loading for both compounds. Stability studies over 90 days revealed no significant changes in physicochemical parameters, confirming the formulation’s robustness. In vitro release assays demonstrated sustained release of both actives, with 58.6 ± 2.9% of CUR and 97 ± 3% of RESV released after 72 h. Antioxidant activity, assessed by the DPPH and ABTS assays, showed concentration-dependent radical-scavenging effects, indicating antioxidant potential. Skin permeation/retention experiments using porcine skin showed enhanced retention of CUR and RESV within the tissue, with no detectable permeation, indicating suitability for topical delivery. In addition, in vitro cell assays using human keratinocytes showed concentration-dependent responses and acceptable cellular compatibility. Conclusions: Overall, this study demonstrates the successful application of nanotechnology and experimental design to develop stable and efficient lipid-based nanocarriers containing natural polyphenol for topical therapy targeting oxidative and inflammatory skin disorders. Full article

Nanoporous gold (np-Au) has attracted significant attention for biomedical and electrochemical applications due to its high surface area, tunable morphology, and excellent biocompatibility. In this study, polycrystalline gold surfaces were modified by anodization in 0.3–0.9 M oxalic acid to produce np-Au layers. The influence of anodization conditions on surface morphology, chemical composition, electronic properties, and corrosion resistance in artificial saliva was systematically investigated. Surface morphology and porosity were analyzed by scanning electron microscopy combined with image analysis, revealing a transition from fine and uniform porosity to highly developed but structurally heterogeneous nanoporous structures with increasing oxalic acid concentration. Energy-dispersive spectroscopy confirmed surface oxidation and adsorption of oxygen- and carbon-containing species after anodization, while gold remained the dominant component. Scanning Kelvin probe measurements demonstrated significant modifications of surface electronic properties, including changes in contact potential difference, governed by nanostructure geometry and surface chemistry. Electrochemical tests in artificial saliva showed that increasing nanoporousness led to reduced thermodynamic stability, with the sample anodized in 0.3 M oxalic acid providing the most favorable balance between corrosion resistance and surface activity. These results demonstrate that oxalic acid anodization is a simple and effective approach for tailoring gold surfaces for biomedical applications, particularly in dentistry. Full article

Hetero-multicomponent metal oxide catalysts are attracting increasing attention for wastewater remediation due to their tunable band structures, synergistic redox activity, and enhanced stability. This review thoroughly evaluates recent progress in the synthesis and application of such catalysts, highlighting Ti–Cu–Zn nanostructures as a representative case study. We examine synthesis approaches—including hydrothermal, biosynthesis, precipitation, and spray-based methods, with additional insight into sol–gel and other less commonly applied techniques—with emphasis on their suitability for constructing layered and multicomponent heterostructures. Mechanistic aspects of photocatalysis, Fenton and Fenton-like processes, adsorption, and electrochemical routes are discussed, with particular focus on charge separation, reactive oxygen species (ROS) generation, and pollutant-specific degradation pathways. Comparative performance metrics against antibiotics, pesticides, dyes, and fertilizers are analyzed, alongside considerations of leaching, reusability, and scale-up potential. Importantly, while significant progress has been made for organic micropollutants, applications in heavy metal remediation remain scarce, highlighting an urgent research gap. By situating Ti–Cu–Zn systems within the broader class of multicomponent catalysts, this review not only synthesizes current advances but also identifies opportunities to expand their role in sustainable wastewater management, including field deployment, regulatory compliance, and integration into decentralized treatment systems. Full article

Double-shell ZnO/Al₂O₃ submicron hollow fibers were successfully fabricated through a combined electrospinning and atomic layer deposition (ALD) approach. Polyvinyl alcohol (PVA) fibers were first produced by electrospinning and subsequently coated with a conformal Al₂O₃ barrier layer via low-temperature ALD employing trimethylaluminum (TMA) and deionized (DI) H₂O to preserve the integrity of the temperature-sensitive polymer core. The inner polymer was then removed using two different techniques—thermal annealing and water dissolution—to compare their effects on the fiber morphology. Finally, a functional ZnO layer was deposited by thermal ALD with diethylzinc (DEZ) and DI H₂O. It was found that the polymer removal method critically determined the final structural and morphological characteristics of the fibers. Thermal annealing resulted in smooth, shrunken fibers, while water dissolution led to diameter expansion and the formation of a highly rough, bubble-like surface structure due to swelling-induced micro-cracking. The selection of the polymer removal method offers a precise and controllable route for tailoring the fiber morphology. The resulting high-aspect-ratio (HAR) structures, particularly the rough and expanded fibers, exhibit enhanced specific surface area, making them highly promising for applications in sensing, catalysis, and filtration. Full article

The field of electrochemical devices, encompassing energy storage, fuel cells, electrolysis, and sensing, is fundamentally reliant on the electrode materials that govern their performance, efficiency, and sustainability. Traditional materials, while foundational, often face limitations such as restricted reaction kinetics, structural deterioration, and dependence on costly or scarce elements, driving the need for continuous innovation. Emerging electrode materials are designed to overcome these challenges by delivering enhanced reaction activity, superior mechanical robustness, accelerated ion diffusion kinetics, and improved economic feasibility. In energy storage, for example, the shift from conventional graphite in lithium-ion batteries has led to the exploration of silicon-based anodes, offering a theoretical capacity more than tenfold higher despite the challenge of massive volume expansion, which is being mitigated through nanostructuring and carbon composites. Simultaneously, the rise of sodium-ion batteries, appealing due to sodium’s abundance, necessitates materials like hard carbon for the anode, as sodium’s larger ionic radius prevents efficient intercalation into graphite. In electrocatalysis, the high cost of platinum in fuel cells is being addressed by developing Platinum-Group-Metal-free (PGM-free) catalysts like metal–nitrogen–carbon (M-N-C) materials for the oxygen reduction reaction (ORR). Similarly, for the oxygen evolution reaction (OER) in water electrolysis, cost-effective alternatives such as nickel–iron hydroxides are replacing iridium and ruthenium oxides in alkaline environments. Furthermore, advancements in materials architecture, such as MXenes—two-dimensional transition metal carbides with metallic conductivity and high volumetric capacitance—and Single-Atom Catalysts (SACs)—which maximize metal utilization—are paving the way for significantly improved supercapacitor and catalytic performance. While significant progress has been made, challenges related to fundamental understanding, long-term stability, and the scalability of lab-based synthesis methods remain paramount for widespread commercial deployment. The future trajectory involves rational design leveraging advanced characterization, computational modeling, and machine learning to achieve holistic, system-level optimization for sustainable, next-generation electrochemical devices. Full article