ACS Materials Au最新文献

Metal halide perovskites (MHPs) have emerged as a class of highly efficient semiconductor materials, attracting widespread interest for their potential applications in photovoltaics, light-emitting diodes, photodetectors, and transistors. Vapor-phase techniques for perovskite synthesis represent a paradigm shift in materials processing, offering precise control over morphology, crystallinity, and composition, while enabling industry-scale manufacturing. This review highlights advancements in vapor-phase synthesis of MHP thin films and micro- and nanostructures, emphasizing strategies to enhance electronic and optical properties, with structural control for next-generation device integration. We introducethe fundamental principles of widely used vapor-phase growth methods and discuss key process modifications employed to control chemical composition, crystal dimension, anisotropic growth, doping, phase purity, and substrate compatibility. We also summarize notable device performance, underscoring the transformative potential of vapor-phase approaches for scalable and high-performance optoelectronic technologies with MHPs.

Wounds significantly impact an individual's quality of life, necessitating a tailored approach to treatment based on the wound's stage of healing and condition. Exudate plays a natural role in recovery, but excessive amounts can complicate wound management, creating a need for advanced therapeutic solutions. Consequently, there is an ongoing demand for advanced therapeutic solutions and innovative wound care devices. Xerogels are gaining recognition as promising materials in wound healing therapeutics due to their unique properties and multifunctional applications. These nanoporous materials, characterized by their large surface area and biocompatibility, can be engineered using various polymers to enhance their effectiveness for specific wound care applications. Their ability to support clot formation and promote tissue regeneration makes them particularly valuable for addressing exudative and chronic wounds. This review offers an in-depth examination of emerging research on xerogels in wound treatment, assessing the current landscape and identifying potential applications of xerogels in various forms including films, grafts, scaffolds, and particles. Additionally, we explore various mechanisms of polymer-based xerogel function and summarize recent patents related to this innovative technology. As research in this area progresses, xerogels utilizing different polymers offer advanced solutions for future wound care therapies.

Nanoparticle gelation is a powerful method for creating porous, crystalline, and translucent aerogels, but it requires stable, concentrated dispersions. Conventional methods for dispersing TiO₂ often rely on strong acids like HCl, which are corrosive and limit compatibility with acid-sensitive materials. In this work, we introduce a novel approach using trisodium citrate to functionalize TiO₂ nanoparticles, forming a highly dispersed colloid stable from pH 3 to 12. This approach enables TiO₂ nanoparticle gelation under previously inaccessible conditions, including slightly acidic (pH = 4), near-neutral (pH = 6.5), and mildly alkaline (pH = 9). Our synthesis uses a metal alkoxide as precursor, avoiding TiCl₄ and eliminating HCl as byproduct. We demonstrate cogelation of silver (Ag) and TiO₂ nanoparticles at near-neutral pH, overcoming Ag corrosion challenges found in acid-based methods. The resulting Ag/TiO₂ aerogels are catalytically active for CO₂-to-CO reduction, a key step in developing fossil-free chemical processes. Under visible light, these aerogels show significantly enhanced catalytic performance, highlighting their promise for photothermal catalysis. This citrate-based, chloride-free route broadens the range of accessible multicomponent aerogel compositions for diverse applications, particularly in the realm of (photo)-catalysis and optical materials.

Gas diffusion determines the performance of metal-organic frameworks (MOFs) in various practical applications, including membrane-based separations, yet its experimental measurement is challenging. We presented an efficient computational framework that integrates high-fidelity molecular dynamics (MD) simulations with machine learning (ML) to predict the diffusivities of CO₂, N₂, O₂, CH₄, and H₂ in >18,000 synthesized and hypothetical MOFs. ML models trained on MD data accurately predicted gas diffusivities of any given MOF within minutes using only easily accessible structural and guest-related properties. We provided an interactive, user-friendly web interface for predicting diffusivities of MOFs to facilitate material selection. Leveraging ML-predicted diffusivities, we evaluated membrane-based gas separation performances of all MOFs for seven industrially important separations: CO₂/N₂, CO₂/CH₄, N₂/CH₄, H₂/CO₂, H₂/CH₄, H₂/N₂, and O₂/N₂. The best MOF membranes offering high selectivity and permeability were identified and analyzed by using molecular fingerprinting to reveal the critical chemical properties for designing next-generation MOFs.

Liquid-phase exfoliation (LPE) of emergent materials composed of weakly bound one-dimensional (1D) and quasi-1D (q-1D) building blocks presents a straightforward route not only for the discovery of confined physical states in 1D but also for the realization of scalable functional devices. However, compared to the more established routes in two-dimensional (2D) crystals, the nature of LPE in 1D and q-1D crystals presents a more random process. This distinction arises from the various available interchain directions across several crystallographic facets unique to 1D and q-1D solids, from which the chains can be cleaved apart into a stochastic combination of nanowires, nanoribbons, and nanosheets. Using the 1D ionic phase comprised of ∼4.3 Å thin chains, (NbSe₄)₃I, we demonstrate herein the profound influence of crystal morphology, exposed facets, and their degree of wettability, passivation, and surface roughness in directing the LPE behavior of 1D crystals. Through the growth of bulk crystals as long needles with exposed (hk0) facets or as quasi-2D flakes with exposed (00l) facets susceptible to passivation, we show that these two distinct precursor morphologies display divergent behaviorboth in solvent preference and quality of resulting nanostructures. Under optimal conditions involving bulk needles and tetrahydrofuran as solvent, we show that the LPE of (NbSe₄)₃I results in ultrathin nanoribbons with high aspect ratios bearing lengths >5 μm, thicknesses down to 7.2 ± 2.6 nm, and widths of 26.4 ± 10.9 nm. The nanoribbons, solution processable as thin films, retain their native crystal structure and semiconducting character. Moreover, the nanoribbons also manifest pronounced degrees of bending and substrate-driven twisting at the nanoscale while maintaining long-range order. These results highlight a means to understand the fundamental chemical and physical behavior of noncovalently bound 1D solids through the realization of solution-processable 1D nanoribbons and nanowires that also have the potential as components for next-generation devices that approach the atomic scale.

Titania aerogels are highly porous materials optimal for photocatalysis due to their high surface area. Further spatial structuring by 3D printing improves gas diffusion in the aerogel, leading to a higher photocatalytic activity. However, the aerogel's mechanical properties are reduced in comparison to non-3D printed aerogels. We hereby present an approach based on atomic layer deposition (ALD) of subnanometer-thin TiO₂ layers to compensate for that detrimental effect. The ALD-deposited TiO₂ consists of amorphous and anatase phase, with the anatase phase likely crystallizing on the aerogel's crystallites. Nanoindentation measurements confirm that the TiO₂ ALD-coatings improve the aerogel's mechanical properties. Additionally, it enhances the photocatalytic properties of the TiO₂ aerogel, which we attribute to the increased interface area and improved interconnection of the nanoparticle network. By further thermal postprocessing, it is possible to fully crystallize the ALD-deposited TiO₂, which shows a complementary effect on photocatalytic performance, improving hydrogen evolution rate by more than 1 order of magnitude from 6.35 to 125 μmol g^-1 h^-1. The combination of 3D structuring of aerogels with ALD coatings demonstrated in this work could be extended in the future to a wide range of materials where the interplay between mechanical and catalytic properties is vital.

Microporous surfaces are widely explored for their potential in applications such as sensing, catalysis, and photonics. However, achieving well-defined and reproducible porous architectures often requires complex or highly optimized fabrication techniques. In this work, we present a straightforward, ultrafast and scalable method for producing functional microporous films by combining spin-coated breath figures of cellulose acetate butyrate with polydopamine-assisted metallization. By systematically investigating the parameters influencing the breath figure process, we demonstrate precise control over the porosity and three-dimensional structure of the resulting films. The incorporation of polydopamine enables the subsequent formation of metal nanoparticles, imparting plasmonic and catalytic functionalities to the surfaces. This versatile platform offers new opportunities for the development of multifunctional materials tailored for advanced sensing and environmental applications.

Innovative radical-type mechano-fluorescent polyurethane (PU) elastomers were developed by integrating axle- and macrocycle-exerted force modes of tetraphenylethylene (TPE)-functionalized daisy chain rotaxanes with expanded/contracted conformations into polymer matrices, revealing distinct mechanical and optical performances under external tensile forces. Surprisingly, the designed PU films containing negligible amounts (0.02% molar ratio of all monomers) of daisy chain structures with unconventional shuttling dimensions (as artificial molecular muscle tougheners) exhibited ultrastretchable capabilities and preeminent toughnesses, possessing a record-high toughness of 1363 MJ/m³ at the strain rate of 20 mm/s, approximately 6.3 times tougher than the standard PU films, along with a significant loading weight ratio of 150,000. Additionally, appealing ratiometric fluorescent responses between blue-emissive TPE stoppers and yellow-emissive diarylacetonitrile radical species could be detected in PU films by stretching due to the introduction of TPE-based daisy chain rotaxanes into mechano-fluorophoric PU skeletons, enabling reversible dual fluorescent switching during tensile loading and unloading processes. Remarkably, notable shape memory and reversible ratiometric fluorescence behaviors of synthetic daisy chain-grafted PU films could be accessible by thermal treatments, indicating probable applications of mechanically interlocked molecule-functionalized PU films with splendid mechanical and optical features for designing stimuli-responsive smart materials.

The conductivity and stability of anion exchange membranes (AEMs) may be significantly enhanced by attaching the cations to the polymer backbones via flexible side chains. Here, we have tethered polydimethylfluorene with the bicyclic "cage-like" N-methylquinuclidinium (PdF-Qui) and the monocyclic N,N-dimethylpiperidinium (PdF-Pip) cations, respectively, via flexible side chains, and studied key AEM properties. Morphological investigations revealed efficient ion clustering in both AEMs, with OH^- conductivities exceeding 120 mS cm^-1 at 80 °C. Alkaline stability studies showed no ionic loss or structural changes in PdF-Qui after storage in a 5 M aqueous NaOH solution at 90 °C for 360 h. In contrast, the benchmark PdF-Pip suffered a 7% loss under the same conditions, primarily via Hofmann elimination. This work presents an efficient synthetic strategy to tether N-methylquinuclidinium cations to polymers for AEMs combining outstanding alkaline stability, efficient ionic clustering, and high OH^- conductivity.

Natural keratin fibers, such as wool, possess a complex hierarchical structure that governs their mechanical properties and surface energy. However, the extent to which these characteristics are influenced by combined contributions of structural variations (e.g., fiber diameter, intermediate filament (IF) packing) and chemical composition (e.g., disulfide bond density) remains poorly understood. In this study, we investigate wool fibers from five sheep breeds (Merino, Polwarth, Cheviot, Eider, and Devon) to elucidate how these factors influence viscoelasticity and surface interactions. Using a multimodal approach integrating interfacial and bulk characterization methods, including inverse gas chromatography (IGC), atomic force microscopy-infrared spectroscopy (AFM-IR), X-ray photoelectron spectroscopy (XPS), uniaxial tensile testing, and synchrotron small-angle X-ray scattering (SAXS), we show that the nanometer-thick 18-methyleicosanoic acid (18-MEA) layer is consistently present across all wool types and plays a key role in governing hydrophobicity and surface heterogeneity. A controlled isothermal treatment at 200 °C, designed to cleave disulfide bonds, results in a nearly 40% reduction in specific surface area across all fiber types, accompanied by a significant decrease in tensile strength and 80% reduction in elongation at break for Merino and Devon wool, but limited influence on the mechanical properties of Eider fibers. Furthermore, rate-dependent tensile testing within the elastic regime reveals distinct viscoelastic responses among the fiber types, suggesting that the sulfur-rich protein matrix surrounding IFs and its structure contribute actively to stress partitioning. Altogether, when combined with conclusions from SAXS measurements of IF spacing, our work offers compelling insights into the role of the keratin-associated protein (KAP) matrix in shaping wool fiber mechanics. Differences in mechanical behavior among wool types, despite similar IF spacing or sulfur content, highlight the importance of matrix composition and cross-linking density, suggesting that the molecular architecture of the KAP network may be a dominant factor in determining fiber performance.