Tunable Morphology Research Articles

Template-Assisted in situ synthesis of superaerophobic bimetallic MOF composites with tunable morphology for boosted oxygen evolution reaction

CoFe bimetallic organic frameworks (CoFe-MOFs) with tunable morphology and electronic structure are synthesized in situ utilizing cobalt hydroxide (Co(OH)2) as a semi-sacrificial template and different anionic iron salts as modifying factors in a non-calcined synthesis method. This work defines the impact of three different anionic metallic iron salts (FeCl3, Fe(NO3)3, and Fe2(SO4)3) on the morphology of MOF materials and their resulting oxygen evolution reaction (OER) catalytic activity. Employing ferric chloride (FeCl3) as the metallic iron source, heterostructured electrocatalysts (BN-CoFe-MOF) with nanoparticles decorated nanoneedle tips are obtained, exhibiting a low overpotential (230 mV at 10 mA cm−2) and a Tafel slope of 105.6 mV dec−1 in 1.0 M KOH. It also demonstrates long time stability for at least 50 h at a current density of 10 mA cm−2. The investigation uncovers that the splendid OER activity and stability of the BN-CoFe-MOF heterojunction can be attributed to its large specific surface area, desirable mesoporous structure, superaerophobic characteristic, and high exposure of active centers. This work not only provides an efficient and cost-effective MOF based OER electrocatalyst but also serves as a valuable reference for future research on morphology control and strategies to enhance the OER activity of MOF catalysts.

Nanofibrous Microspheres: A Biomimetic Platform for Bone Tissue Regeneration.

Bone, a fundamental constituent of the human body, is a vital scaffold for support, protection, and locomotion, underscoring its pivotal role in maintaining skeletal integrity and overall functionality. However, factors such as trauma, disease, or aging can compromise bone structure, necessitating effective strategies for regeneration. Traditional approaches often lack biomimetic environments conducive to efficient tissue repair. Nanofibrous microspheres (NFMS) present a promising biomimetic platform for bone regeneration by mimicking the native extracellular matrix architecture. Through optimized fabrication techniques and the incorporation of active biomolecular components, NFMS can precisely replicate the nanostructure and biochemical cues essential for osteogenesis promotion. Furthermore, NFMS exhibit versatile properties, including tunable morphology, mechanical strength, and controlled release kinetics, augmenting their suitability for tailored bone tissue engineering applications. NFMS enhance cell recruitment, attachment, and proliferation, while promoting osteogenic differentiation and mineralization, thereby accelerating bone healing. This review highlights the pivotal role of NFMS in bone tissue engineering, elucidating their design principles and key attributes. By examining recent preclinical applications, we assess their current clinical status and discuss critical considerations for potential clinical translation. This review offers crucial insights for researchers at the intersection of biomaterials and tissue engineering, highlighting developments in this expanding field.

Investigation of electrospinning parameters and fiber collection methods on morphology of thermoplastic polyester elastomer fibers

Electrospinning is an easy and simple process for the preparation of ultrafine fibers with tunable morphology. Thermoplastic Elastomers (TPEs) are engineering polymers with an elastomeric nature that can be processed as thermoplastics. They can be classified based on their chemical structure and polyester-based TPEs are counted as high-performance materials due to their mechanical properties and can be used for various applications from automotive, construction, furniture, and consumer goods. In this study, electrospun polyester-based thermoplastic elastomer fibers were prepared and characterized. Thermoplastic polyester elastomer, Hytrel 4056 was used as the polymer, and chloroform was used as a solvent. The effects of polymer: solvent weight ratio, feed rate, applied voltage, and collector type were investigated in terms of fiber formation and morphology. For this aim, the polymer: solvent weight ratio was varied as 1:7, 1:11, and 1:15; the feed rate was set to 1 and 3 ml h-1. To collect the fibers metal plate and water bath collectors were used at a constant needle-to-collector distance under 10, 15, and 20 kV. The viscosity of the polymer solutions was measured as a function of the polymer: solvent ratio to observe the effects of viscosity on fiber morphology.

Mixed‐Dimensional All‐Organic Polymer Heterostructures with Enhanced Piezoelectricity

AbstractEnhancing the piezoelectricity of polymers while maintaining all components organic is still challenging but significantly important for developing flexible wearable energy harvesters and self‐powered devices. Here, a novel and versatile strategy is introduced to construct mixed‐dimensional all‐organic polymer heterostructures (MPHs) for enhanced piezoelectricity. By combining all‐polymer 1D nanofibers (NFs) with 2D crystals through epitaxial crystallization‐driven assembly (ECA), MPHs are engineered to capitalize on the synergistic effects of both dimensional nanostructures. The intrinsic piezoelectric activity of 1D NFs is amplified by the growth of 2D crystals, enhancing force‐sensitivity and overall piezoelectricity. The mixed‐dimensional assembly not only enables controlled in‐situ growth of MPHs, but also simultaneously induces preferential formation of electroactive phases through solvent‐induced phase transition. By modulating the epitaxial growth of 2D crystals on 1D NFs, effective tuning of MPH growth amount and morphology is achieved, resulting in significant improvements in deformability, dipole polarization, and durability. MPHs exhibit remarkable piezoelectric improvements, achieving higher output under lower‐level forces with a record‐high sensitivity of ≈670 mV kPa−1. Their superior responsivity enables the development of self‐powered wireless wearable motion‐monitoring systems for real‐time physiological movement detection and analysis. This work inspires the development of all‐organic piezoelectric devices for innovative flexible energy‐harvesting and sensing applications.

Spatiotemporal-Dependent Confinement Effect of Bubble Swarms Enables a Fractal Hierarchical Assembly with Promoted Chirality.

The submarine-confined bubble swarm is considered an important constraining environment for the early evolution of living matter due to the abundant gas/water interfaces it provides. Similarly, the spatiotemporal characteristics of the confinement effect in this particular scenario may also impact the origin, transfer, and amplification of chirality in organisms. Here, we explore the confinement effect on the chiral hierarchical assembly of the amphiphiles in the confined bubble array stabilized by the micropillar templates. Compared with the other confinement conditions, the assembly in the bubble scenario yields a fractal morphology and exhibits a unique level of the chiral degree, ordering, and orientation consistency, which can be attributed to the characteristic interfacial effects of the rapidly formed gas/water interfaces. Thus, molecules with a balanced amphiphilicity can be more favorable for the promotion. Not limited to the pure enantiomers, chiral amplification of the enantiomer-mixed assembly is observed only in the bubble scenario. Beyond the interfacial mechanism, the fast formation kinetics of the confined liquid bridges in the bubble scenario endows the assembly with the tunable hierarchical morphology when regulating the amphiphilicity, aggregates, and confined spaces. Furthermore, the chiral-induced spin selectivity (CISS) effect of the fractal hierarchical assembly was systematically investigated, and a strategy based on photoisomerization was developed to efficiently modulate the CISS effect. This work provides insights into the robustness of confined bubble swarms in promoting a chiral hierarchical assembly and the potential applications of the resulting chiral hierarchical patterns in solid-state spintronic and optical devices.

Combination of methylthio-chemistry with living crystallization-driven self-assembly toward uniform π-conjugated nanostructures with antibacterial activity, surface tailorability, tunable morphology and dimension

Combination of methylthio-chemistry with living crystallization-driven self-assembly toward uniform π-conjugated nanostructures with antibacterial activity, surface tailorability, tunable morphology and dimension

Dynamic Cleavage-Remodeling of Covalent Organic Networks into Multidimensional Superstructures.

Superstructures with complex hierarchical spatial configurations exhibit broader structural depth than single hierarchical structures and the associated broader application prospects. However, current preparation methods are greatly constrained by cumbersome steps and harsh conditions. Here, for the first time, a concise and efficient thermally responsive dynamic synthesis strategy for the preparation of multidimensional complex superstructures within soluble covalent organic networks (SCONs) with tunable morphology from 0D hollow supraparticles to 2D films is presented. Mechanism study reveals the thermally responsive dynamic "cleavage-remodeling" characteristics of SCONs, synthesized based on the unique bilayer structure of (2.2)paracyclophane, and the temperature control facilitates the process from reversible solubility to reorganization and construction of superstructures. Specifically, during the process, the oil-water-emulsion two-phase interface can be generated through droplet jetting, leading to the preparation of 0D hollow supraparticles and other bowl-like complex superstructures with high yield. Additionally, by modulating the volatility and solubility of exogenous solvents, defect-free 2D films are prepared relying on an air-liquid interface. Expanded experiments further confirm the generalizability and scalability of the proposed dynamic "cleavage-remodeling" strategy. Research on the enrichment mechanism of guest iodine highlights the superior kinetic mass transfer performance of superstructural products compared to single-hierarchical materials.

Exploring Colloidal Phase Transitions of Imogolite Nanotubes by Evaporation Induced Self‐Assembly in Levitation

AbstractEvaporation‐induced self‐assembly (EISA) is a versatile method for generating organized superstructures from colloidal particles, offering diverse design possibilities through the manipulation of colloid size, shape, substrate nature, and environmental conditions. While some work highlighted the potential of EISA to investigate phase transitions of inorganic liquid crystals, the influence of sample environment to determine their phase diagrams is often overlooked. In this work, the self‐assembly of lyotropic liquid crystals is compared by EISA on substrates, and by acoustic levitation (absence of substrate). The focus is on imogolite nanotubes, a model colloidal system of 1D charged objects, due to their tunable morphology and rich liquid‐crystalline phase behavior. It demonstrates the feasibility to obtain phase transitions in levitating droplets and on soft hydrophobic substrates, whereas self‐assembly is limited on rigid hydrophilic supports. Moreover, the aspect ratio of the nanotubes proves to be a pivotal factor, influencing both transitions and the resulting materials shape and surface. Besides material shaping, acoustic levitation emerges as a promising method for studying phase transitions by EISA, toward the rapid establishment of phase diagrams from diluted to highly concentrated states using a limited volume of sample.

Intercage Polymerization of Postfunctionalized Phosphine Organic Prisms into Cage-Based Assemblies with Tunable Morphologies.

Great effort has been dedicated to the engineering of porous organic cages (POCs) in geometry and topology. Yet, harnessing these cage-like entities as premade building units to construct infinite cage-based superstructures remains elusive. In this study, we design a type of vertex-modified phosphine organic prism by a postfunctionalized approach and use it as a ditopic cage monomer to achieve an intercage supramolecular polymerization via the synergy of metal coordination and π-π dimerization. The resulting cage-by-cage polymers can further hierarchically organize into superstructures of diverse morphologies and dimensionalities, including 1D fibers, 2D lamellae, and 3D vesicles. Control over the cosolvents is capable of well regulating their structural hierarchies and self-assembled shapes. This would pave a way for the creation of cage-based supramolecular assemblies and nanomaterials.

Low voltage flexible high performance organic field-effect transistor and its application for ultraviolet light detectors

ABSTRACT A novel highly π-extended heteroarene Benzo[1,2-b:4,5-b’]di(naphtho[1,2-d]thiophene) (DBTBT) was used for organic field-effect transistors (OFETs). The mobilities of OFET were greatly improved from 0.34–0.58 cm2V−1s−1 to 1.02–1.75 cm2V−1s−1 by morphology tuning through 2 steps’ controlling substrate temperature. More importantly, the OFETs showed a good ambient stability in 30 days measurements. The flexible OFET arrays were prepared on polyethylene terephthalate substrate with octadecyl trichlorosilane modified polymethylsilsesquioxane/polyacrylonitrile gate dielectrics and demonstrated a 100% yield. Further, this flexible cell was used for ultraviolet light detection, which showed good ability of detecting low power light (such as λ = 254 nm, 7 μW/cm2).

Electrospray Deposition for Electronic Thin Films on 3D Freeform Surfaces: From Mechanisms to Applications

AbstractElectronic thin films play a ubiquitous role in microelectronic devices and especially hold great promise for flexible electronics, energy conversion and storage, and biomedical applications. Their characterizations, including ultra‐thin, large‐scale dimensions, stretchability, and conformal ability to curved or 3D structures, present new challenges for thin film fabrication based on the solution method. Electrospray deposition emerges as a feasible method for fabricating large‐area, flexible, and curved films. It offers many advantages such as material adaptability, controlled atomization, tunable film morphology, and shape retention on complex substrates. These advantages make it a key method for fabricating high‐performance films on large‐area, 3D surfaces. This work presents a comprehensive review of the mechanisms, processes, applications, and equipment of electrospray deposition. First, the fundamental principles of electrospray deposition are introduced, focusing on the mechanisms and scaling laws of liquid atomization. Moreover, the control methods for electrospray modes, structures, and film morphology are discussed. These advanced control methods pave the way for the fabrication of smart skins, wearable devices, and energy conversion and storage components. Finally, this work introduces three types of electrospray deposition manufacturing equipment to illustrate the advantages of electrospray deposition for large‐area, and 3D surface manufacturing.

Flexible Centrifugally Spun N, S-Doped SnS2-Including Porous Carbon Nanofiber Electrodes for Na-Ion Batteries.

Carbon nanofibers are promising for various applications such as energy storage, sensors, and biomedical applications; however, the brittle structure of nanofibers limits the usage of carbon nanofibers. For the first time, a facile and effective strategy is reported to fabricate flexible carbon nanofibers via a fast and safe nanofiber fabrication technique, centrifugal spinning, followed by heat treatment. Moreover, sulfidization was employed to fabricate high-performance flexible N, S-doped SnS2-including porous carbon nanofiber electrodes for sodium ion batteries via centrifugal spinning. Binder-free flexible centrifugally spun N, S-doped SnS2-including porous carbon nanofiber electrodes delivered a high reversible capacity of over 460 mAh/g at 100 mA/g. Furthermore, at a high current density of 1 A/g, the electrodes showed a reversible capacity of over 300 mAh/g with excellent cycling stability in 2000 cycles. This work reports a fast, low-cost, and facile way to prepare flexible carbon nanofibers with tunable morphology and various compositions, which could be applicable for different energy storage applications.

Highly Stretchable Polyurethane Porous Membranes with Adjustable Morphology for Advanced Lithium Metal Batteries.

A highly flexible, tunable morphology membrane with excellent thermal stability and ionic conductivity can endow lithium metal batteries with high power density and reduced dendrite growth. Herein, a porous Polyurethane (PU) membrane with an adjustable morphology was prepared by a simple nonsolvent-induced phase separation technique. The precise control of the final morphology of PU membranes can be achieved through appropriate selection of a nonsolvent, resulting a range of pore structures that vary from finger-like voids to sponge-like pores. The implementation of combinatorial DFT and experimental analysis has revealed that spongy PU porous membranes, especially PU-EtOH, show superior electrolyte wettability (472%), high porosity (75%), good mechanical flexibility, robust thermal dimensional stability (above 170 °C), and elevated ionic conductivity (1.38 mS cm-1) in comparison to the polypropylene (PP) separator. The use of PU-EtOH in Li//Li symmetric cell results in a prolonged lifespan of 800 h, surpasing the longevity of PU or PP cells. Moreover, when subjected to a high rate of 5 C, the LiFePO4/Li half-cell with a PU-EtOH porous membrane displayed better cycling performance (115.4 mAh g-1) compared to the PP separator (104.4 mAh g-1). Finally, the prepared PU porous membrane exhibits significant potential for improving the efficiency and safety of LMBs.

Directed Assembly of Elastic Fibers via Coacervate Droplet Deposition on Electrospun Templates.

Elastic fibers provide critical elasticity to the arteries, lungs, and other organs. Elastic fiber assembly is a process where soluble tropoelastin is coacervated into liquid droplets, cross-linked, and deposited onto and into microfibrils. While much progress has been made in understanding the biology of this process, questions remain regarding the timing of interactions during assembly. Furthermore, it is unclear to what extent fibrous templates are needed to guide coacervate droplets into the correct architecture. The organization and shaping of coacervate droplets onto a fiber template have never been previously modeled or employed as a strategy for shaping elastin fiber materials. Using an in vitro system consisting of elastin-like polypeptides (ELPs), genipin cross-linker, electrospun polylactic-co-glycolic acid (PLGA) fibers, and tannic acid surface coatings for fibers, we explored ELP coacervation, cross-linking, and deposition onto fiber templates. We demonstrate that integration of coacervate droplets into a fibrous template is primarily influenced by two factors: (1) the balance of coacervation and cross-linking and (2) the surface energy of the fiber templates. The success of this integration affects the mechanical properties of the final fiber network. Our resulting membrane materials exhibit highly tunable morphologies and a range of elastic moduli (0.8-1.6 MPa) comparable to native elastic fibers.

Metal-Organic Framework for Aluminum based Energy Storage Devices: Utilizing Redox Additives for Significant Performance Enhancement.

There are various methods being tried to address the sluggish kinetics observed in Al-ion batteries (AIBs). They mostly deal with morphology tuning, but have led to limited improvement. A new approach is proposed to overcome this limitation. It focuses on the use of a redox additive modified electrolyte in combination with framework like materials, which have wider channels. The ordered microporous and interconnected framework of ZIF 67, with large surface area, effectively facilitates the diffusion of aluminum ions. Therefore, AIBs are able to exhibit a superior discharge capacity of 288 mAh g-1 at 0.2 A g-1 current density with robust cycling stability. The addition of potassium ferricyanide as a redox-active species in an aqueous solution of aluminum chloride (supporting electrolyte) leads to significant enhancement in the specific capacity with much higher cycling stability. Al-ion based BatCap devices can be assembled by using ZIF 67 as the cathode, ZIF 67 derived porous carbon as the anode, and a redox additive modified electrolyte. The BatCap device exhibits excellent energy density of 86 Wh kg-1 at a power density of 2 KW kg-1, which is higher than reported aqueous AIBs. The ex situ characterization clearly explains the unexplored mechanism of redox additives in AIBs.

Rational design and synthesis of BiOF micro/nanostructures with enhanced photocatalytic properties

BiOF with tunable morphologies (polygonal disk-shaped columns, polygonal flakes and square flakes) have been prepared via a facile hydrothermal route, in which nitrilotriacetic acid (NTA) was used as a structure directing reagent. It was found that the morphologies and crystalline structures of the as-obtained BiOF were dependent on the NTA dosage and the pH value. Based on the observation of the photocatalytic selectivity of typical polygonal disk-shaped columns of BiOF towards different types of organic dyes, we further investigated the photocatalytic activities of the BiOF with different morphologies by the degradation of malachite green (MG) solution under UV light irradiation. The results showed that disk-shaped columns of BiOF had the best photocatalytic activity, and the degradation rate of MG reached 95.34 % after 20 min of irradiation. The photocatalytic efficiency was much higher than those of other morphological BiOF micro/nanostructures. The results of this study strongly indicate that BiOF has a broad application prospect in the field of photocatalysis.

Recent Developments of Nanostructured Photocatalysts Based on Semiconducting Chalcogenides for Organic Reactions

Abstract:: The earth-abundant metal chalcogenide is a highly versatile semiconductor with unique electronic and optical properties that seem to outperform the photocatalytic properties of metal oxides and metal nanoparticles. For ages, researchers are reaping the benefits of its photocatalytic properties in numerous reactions. However, the high charge recombination rates, poor compositional stability, and a smaller number of catalytically active sites restrict its application. The development of different kinds of heterojunctions by the combination of metal-chalcogenides with other conducting and semiconducting materials like metal oxides, metal nanoparticles, g-C3N4, single-atom catalysts, and MOF results in superior photocatalytic activity. This review provides insight into the various classes of metal-chalcogenide-based heterostructures and their application in various organic transformations. A brief overview of the synergistic properties arising from the development of such heterostructures helps to understand the surface interactions so that highly stable, efficient, and selective metal-chalcogenide-based heterostructures can be developed for industrially important photocatalytic organic transformations. This review also describes the role of mediators in boosting the stability and catalytic efficiency of the metal chalcogenides. Moreover, a thorough emphasis on the morphological impact of photocatalysts in various reactions will help with the development of metal chalcogenide heterostructures with tunable morphology and bandgap.

Fabrication of controlled porous and ultrafast dissolution porous microneedles by organic-solvent-free ice templating method

Porous Microneedles (PMNs) have been widely used in drug delivery and medical diagnosis owing to their abundant interconnected pores. However, the mechanical strength, the use of organic solvent, and drug loading capacity have long been challenging. Herein, a novel strategy of PMNs fabrication based on the Ice Templating Method is proposed that is suitable for insoluble, soluble, and nanosystem drug loading. The preparation process simplifies the traditional microneedle preparation process with a shorter preparation time. It endows the highly tunable porous morphology, enhanced mechanical strength, and rapid dissolution performance. Micro-CT three-dimensional reconstruction was used to better quantify the internal structures of PMNs, and we further established the equivalent pore network model to statistically analyze the internal pore structure parameters of PMNs. In particular, the mechanical strength is mainly negatively correlated with the surface porosity, while the dissolution velocity is mainly positively correlated with the permeability coefficient by the correlation heatmap. The poorly water-soluble Asiatic acid was encapsulated in PMNs in nanostructured lipid carriers, showing prominent hypertrophic scar healing trends. This work offers a quick and easy way of preparation that may be used to expand PMNs function and be introduced in industrial manufacturing development.

Synthesis of NaYbF4:Er nanocrystals with controllable size, morphology, and multicolor upconversion luminescence for Anticounterfeiting applications

The dopant concentration of lanthanide ions plays one of the critical roles to manipulate size/morphology, photon population pathway, or luminescence color/intensity in upconversion nanoparticles (UCNCs), which have a significant effect on their application developments. Herein, a strategy is demonstrated for simultaneous size, morphology and multicolor luminescence tuning in the single doped lanthanide activator Er3+ ion system through simply tuning the concentration of Er3+ ions. The doping of different Er3+ ion amounts in NaYbF4:Er nanocrystals can control nanoparticle size (from several hundreds to tens of nanometers) and morphology. Moreover, multicolor upconversion luminescence involving green, yellow, orange and red can be obtained in the NaYbF4:Er UCNCs by changing the excitation power density of 980 nm laser. Mechanistic studies reveal the size and morphology evolution process as well as saturation/cross relaxation effects induced tunable multicolor emissions. These nanocrystals have demonstrated promising potential applications in anticounterfeiting. Our results not only provide a simple and feasible route for simultaneous size/morphology control and multicolor upconversion luminescence tuning, but also can further expand the utility of UCNCs in the frontier applications ranging from optical encoding to information security.

MOFs-derived 3D flower-like Y2O3/C microspheres with efficient electromagnetic wave absorption properties

Y2O3 has emerged as a promising material for electromagnetic wave (EMW) absorption due to its excellent dielectric properties. However, the inherent insulating nature and single loss mechanism limit its absorption performance. Research on the microstructure modulation and component regulation of Y2O3-based absorbers remains relatively unexplored. In this work, Y2O3/C composites with flower-like architectures were synthesized for the first time via a metal-organic framework (MOFs) templating method. The effects of pyrolysis temperature on the microstructure, phase composition, and EMW absorption performance of the Y2O3/C composites were systematically investigated. At a pyrolysis temperature of 800 °C, the flower-like Y2O3/C microsphere exhibited optimal EMW absorption performance. The minimum reflection loss (RL) of pristine Y2O3 was only −4.75 dB, while the Y2O3/C composite achieved a minimum RL of −51.77 dB and a maximum effective absorption bandwidth of 4.32 GHz. Moreover, by simply adjusting the matching thickness, the optimal sample exhibited strong absorption (RL < −30 dB) over a wide frequency range of 4–18 GHz. The incorporation of carbon effectively neutralized the insulating nature of Y2O3, thereby optimizing the impedance matching. The synergistic effects of multiple loss mechanisms, including polarization loss, resistance loss, and interfacial polarization, facilitated substantial EMW attenuation. This study provides a promising strategy for the design and fabrication of high-performance rare-earth oxide EMW absorbers with tunable morphologies and properties.