Tunable Morphology Research Articles

Recent advancements in the application of electrospun nanofibers for carbon dioxide capture and utilization

The escalating CO2 emissions in recent years underlined the need for advanced Carbon Capture and Utilization (CCU) technologies. This context has spurred the exploration of novel materials for promoting CCU efficiency, among which electrospun nanofibers have emerged as a promising candidate. Electrospinning coupled with various post-treatment (such as heat-treating, in-situ growth, selective removal, etc.) offers a versatile approach to fabricate diverse nanofibers, including polymeric, carbonaceous, metallic, and composite fibers, with tunable surface morphologies and chemical properties. This paper provides a comprehensive review of electrospun nanofibers in CCU processes, including adsorption, membrane separation and absorption, electrochemical and photo-electrochemical reduction, thermal catalytic hydrogenation, and more. Each CCU technology is examined in depth to cover the recent research achievements with a specific focus on the contributions of electrospun nanofibers. Lastly, a critical discussion and a list of potential future research directions for this evolving field are provided.

The Mechanism of Manipulating Chirality and Chiral Sensing Based on Chiral Plexcitons in a Strong-Coupling Regime.

Manipulating plasmonic chirality has shown promising applications in nanophotonics, stereochemistry, chirality sensing, and biomedicine. However, to reconfigure plasmonic chirality, the strategy of constructing chiral plasmonic systems with a tunable morphology is cumbersome and complicated to apply for integrated devices. Here, we present a simple and effective method that can also manipulate chirality and control chiral light-matter interactions only via strong coupling between chiral plasmonic nanoparticles and excitons. This paper presents a chiral plexcitonic system consisting of L-shaped nanorod dimers and achiral molecule excitons. The circular dichroism (CD) spectra in our strong-coupling system can be calculated by finite element method simulations. We found that the formation of the chiral plexcitons can significantly modulate the CD spectra, including the appearance of new hybridized peaks, double Rabi splitting, and bisignate anti-crossing behaviors. This phenomenon can be explained by our extended coupled-mode theory. Moreover, we explored the applications of this method in enantiomer ratio sensing by using the properties of the CD spectra. We found a strong linear dependence of the CD spectra on the enantiomer ratio. Our work provides a facile and efficient method to modulate the chirality of nanosystems, deepens our understanding of chiral plexcitons in nanosystems, and facilitates the development of chiral devices and chiral sensing.

Studies toward Morphological Changes of Silver/Carbon Fiber Composites and Their Optimization for High-Performance Electrochemical Electrodes

The integration of micro/nanostructured metal/metal oxides with carbon-based materials has emerged as a promising approach for developing electrochemical electrodes. However, the fabrication of such hybrids entails complex and multistep procedures involving the grain boundaries and interfaces between the constituent materials, thus, degrading the overall performance. Herein, we report a facile electrothermal process (ETP) for the scalable fabrication of hybrid carbon fiber (CF) sheets integrated with tunable morphology of silver micro/nanoparticles. The application of an electric field across the layered film, consisting of AgNO3 and CF, enabled the rapid dissipation of thermochemical energy in an open-air environment via ETP. The ETP facilitated ultrafast heat dissipation within a few milliseconds, leading to the rapid decomposition of AgNO3, which resulted in the formation of liquefied Ag on the CF surface affording a reduced Ag-CF composite with adjustable structures through input power. The capability of ETP driven by controlling duration and number of electrical pulses was demonstrated by examining the corresponding physiochemical and electrochemical characteristics of the resulting composite. The Ag-CF composite fabricated using three cycles of a screened ETP pulse (1500 W and 75 ms for power and duration) acted as a supercapacitor electrode demonstrating excellent area capacitance (13 F/cm2) and exceptional capacitance retention (98% after 10,000 cycles). Thus, the utilization of ETP can provide manufacturing strategies enabling scalable synthesis of functional hybrids in vacuum-free ambient environments within milliseconds. These hybrids possess unique interfaces and particle boundaries, exhibiting considerable potential for diverse electrochemical applications.

Morphological and size tuning of biogenic Ag and Au nanoparticles induced by laser irradiation

Since size and shape of the metal nanoparticles (NPs) determine its physical and chemical properties, such could be relevant for specific applications; it is critical to have adequate control over such features. In this work, a facile bottom-up, bio-inspired synthetic route for noble metal nanoparticles (NPs) preparation is presented. Specifically, Ag and Au monometallic nanoparticles were synthesized by bio-reduction with Citrus paradisi (Grapefruit) aqueous extract. Besides, conventional chemical reduction synthesis using NaBH4 and PVP as capping agent was also performed for comparison purposes. Characterization accomplished by UV–vis spectroscopy and electron microscopy over the synthesized nanoparticles shown that, although that unimodal (in the case of Ag NPs) or almost unimodal (Au NPs) size distributions were obtained, thanks to stabilizing effect of the ligand acting-biomolecules present in the extract; and the narrower size distribution in comparison with the conventional chemical synthesis route were observed, several morphologies were found for both metals. In order to modify such features, the obtained noble metal NPs were submitted to pulsed (30 ps, 10 mJ) Nd:YAG laser irradiation process; after that, the spherical shape seems to be the predominant morphology in both metal nanoparticles, whereas the population of particles smaller than 15 nm became increases considerably.

Bottom-Up Synthesized Glucan Materials: Opportunities from Applied Biocatalysis.

Linear d-glucans are natural polysaccharides of simple chemical structure. They are comprised of d-glucosyl units linked by a single type of glycosidic bond. Noncovalent interactions within, and between, the d-glucan chains give rise to a broad variety of macromolecular nanostructures that can assemble into crystalline-organized materials of tunable morphology. Structure design and functionalization of d-glucans for diverse material applications largely relies on top-down processing and chemical derivatization of naturally derived starting materials. The top-down approach encounters critical limitations in efficiency, selectivity, and flexibility. Bottom-up approaches of d-glucan synthesis offer different, and often more precise, ways of polymer structure control and provide means of functional diversification widely inaccessible to top-down routes of polysaccharide material processing. Here the natural and engineered enzymes (glycosyltransferases, glycoside hydrolases and phosphorylases, glycosynthases) for d-glucan polymerization are described and the use of applied biocatalysis for the bottom-up assembly of specific d-glucan structures is shown. Advanced material applications of the resulting polymeric products are further shown and their important role in the development of sustainable macromolecular materials in a bio-based circular economy is discussed.

Effect of nickel sulfide catalysts with different morphologies on high efficiency alkaline hydrogen evolution reaction

An important area of research is the creation of non-precious metal catalysts with increased catalytic activity and stability for the electrolysis of water to produce hydrogen. A viable and effective method for altering the surface structure of electrocatalysts and improving their performance is morphology control. In this study, the amount of ammonium fluoride (NH4F) used in the hydrothermal process was changed to create a range of nickel sulfide (NiS) electrocatalysts with tunable morphologies. The improved NiS catalyst demonstrated exceptional performance in the hydrogen evolution process (HER) because of its expansive active area, elevated surface activity, and gas diffusion channels. In particular, it showed a low Tafel slope of 65.90 mV dec−1 in 1 M KOH electrolyte solution and an overpotential of 97 mV at a current density of 10 mA cm−2. Remarkably, the NiS electrocatalyst maintained its excellent HER performance even after 60-hour durability test. These findings underscore the significance and feasibility of morphology control in achieving desirable catalytic activity.

Regulating potassium storage kinetics in mesoporous carbon spheres via delicate inner structural design

Carbon materials have been considered to be potential anodes for potassium-ion batteries (PIBs). Different strategies, including designing micro-/nano-structure and porous morphology, introducing heteroatom doping, and creating carbon-based hybrids, have been employed to improve the potassium ion transport kinetics. Nevertheless, it is still a challenge to achieve satisfactory potassium storage performance due to the uncontrolled reaction kinetics of the large-sized potassium ions. Herein, we successfully synthesized mesoporous carbon spheres (MCSs) with tunable internal morphology and structure by using sacrificed template method. The optimized MCSs with novel half inner-shell structures (HIS-MCSs) show excellent electrochemical performance when used as the anode for PIBs. Specifically, a reversible specific capacity of 241.2 mAh/g is achieved at a current density of 0.1 A/g. Even at 5.0 A/g, a reversible specific capacity of 120 mAh/g can still be reached. Long-term stability tests show that the electrode holds a capacity of 166.5 mAh/g after 1000 cycles at 1.0 A/g. The good cycling stability and rate performance of the HIS-MCSs electrode are attributed to the well-defined inner structural design, in which the contribution from ion diffusion and pseudo-capacitance process are compromised.

Preparation of Tunable Cu−Ag Nanostructures by Electrodeposition in a Deep Eutectic Solvent

AbstractThe green transition requires new, clean, inexpensive, and sustainable strategies to prepare controllable bimetallic and multimetallic nanostructures. Cu−Ag nanostructures, for example, are promising bimetallic catalysts for different electrocatalytic reactions such as carbon monoxide and carbon dioxide reduction. In this work, we present the one‐step preparation method of electrodeposited Cu−Ag with tunable composition and morphology from choline chloride plus urea deep eutectic solvent (DES), a non‐toxic and green DES. We have assessed how different electrodeposition parameters affect the morphology and composition of our nanostructures. We combine electrochemical methods with ex‐situ scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDS), and X‐ray photoelectron spectroscopy (XPS) to characterize the nanostructures. We have estimated the electrochemically active surface area (ECSA) and roughness factor (R) by lead underpotential deposition (UPD). The copper/silver ratio in the electrodeposited nanostructures is highly sensitive to the applied potential, bath composition, and loading. We observed that silver‐rich nanostructures were less adherent whereas the increase in copper content led to more stable and homogenous films with disperse rounded nanostructures with tiny spikes. These spikes were more stable when the deposition rate was fast enough and the molar ratio of Cu and Ag was no greater than approximately two to one.

Tunable evaporation-induced surface morphologies on chitosan film for light management

The surface morphologies of polymer films have been used to improve the performance or enable new applications of films, such as controllable adhesion, shape morphing and light management. However, complicated and destructive methods were applied to produce surface morphologies on chitosan (CS) film. To overcome this challenge, we report an evaporation-induced self-assembly to form the tunable morphologies on the surface of short-chain chitosan film by varying the evaporation rates that influence the aggregation behavior of polymer chains between order and disorder. It enables the simple, tunable and scalable fabrication of surface morphologies on CS film (CS solution concentration: 2 wt%, drying from room temperature (RT) to 80 °C) that provides controllable haze (3–74 %) and high transmittance (>85 %) for the production of hazy and transparent window coatings. This simple approach to producing tunable surface morphologies could inspire the synthesis of multifunctional polymer films with different surface structures, whose applications can be extended to cell culture interfaces, flexible bioelectronic and optoelectronic devices.

Multi-dimensional nano-microstructures design of MOF-derived CoSe2@N–C composites toward excellent microwave absorption

Nano-microstructures design enabled the controlled tuning of electromagnetic parameters to obtain high-performance microwave absorption materials (MAM). Herein, Metal-Organic Frameworks-derived (MOFs-derived) CoSe2@Nitrogen-doped Carbon (CoSe2@N–C) materials with controllable nano-microstructures also exhibit tunable morphologies from dodecahedra-, cube-, fusiform-to sheet-like by adjusting the solvent and the molar ratio of cobalt/ligand. The organic frameworks are maintained by pyrolysis selenization, forming a unique CoSe2@N–C three-dimensional conduction network that broadens electron transport and electromagnetic wave multiple reflection routes, enhances conduction loss capability, and optimizes impedance matching. The confinement of ligand-derived carbon can avoid the agglomeration of CoSe2, forming rich heterogeneous interfaces within CoSe2@N–C, enhancing interfacial polarization loss. Symmetric models are developed to reveal the importance of destructive interference on the microwave absorption property. In addition, dipole polarization of defects and doped-nitrogen further encourages the enhancement of the microwave absorption properties of CoSe2@N–C. The CoSe2@N–C-d exhibits the best microwave absorption properties with a minimum reflection loss (RLmin) of −42.31 dB at 15.62 GHz in a thickness of 1.5 mm, and an effective absorption bandwidth of 4.25 GHz. The excellent absorption performance of CoSe2@N–C paves the way for the design and synthesis of high-performance absorbers.

Tunable Fluorescence, Morphology, and Antibacterial Behaviors of Conjugated Oligomers via Host-Guest Supramolecular Self-Assembly.

Host-guest supramolecular self-assembly has become one facile but efficient way to regulate the optical properties of conjugated oligomers and construct promising photofunctional materials. Herein, we design two linear conjugated oligomers terminated with two or four pyridinium moieties, which show different 1:1 'head-to-tail' binding patterns with cucurbit[8]uril (CB[8]) to form host-guest supramolecules. After being encapsulated in the hydrophobic cavity of the CB[8] host, the fluorescence emission of the conjugated oligomers undergoes significant changes, resulting in tunable fluorescence color with enhanced quantum yields. Triggered by the aggregation of supramolecules, the regular or rigid binding modes lead to the formation of cuboids and spheroids in nanoscale, respectively. Due to the macrocyclic-confinement effect, the light-driven reactive oxygen species (ROS) production of the host-guest complex is increased significantly, thereby improving the photodynamic antibacterial performance toward Staphylococcus aureus (S. aureus).

Magnetic MOF-derived materials with tunable morphology modified by ZnO to activate peroxydisulfate

Magnetic MOF-derived materials with tunable morphology modified by ZnO to activate peroxydisulfate

Thermal Enhancement of Upconversion in Sub‐10 nm Yb3+/Er3+/Na+ Tridoped Cs2ZrF6 Nanocrystals for Ratiometric Temperature Sensing

AbstractAlkaline zirconium fluorides (AxZryFx+y, A = Li, Na, and K), featuring unique crystallographic structures, have recently emerged as a class of attractive hosts for fabricating lanthanide (Ln3+)‐doped upconversion nanocrystals (UCNCs) that exhibited distinct morphology, upconversion luminescence (UCL) performance, and physicochemical property. In this paper, for the first time the controlled preparation of Yb3+/Er3+‐doped UCNCs is reported based on the trigonal Cs2ZrF6 host, leading to tunable morphology and size of the resulting UCNCs by varying the reaction temperature and time. By further incorporating Na+ ions into the Cs2ZrF6 crystal lattice, sub‐10 nm Yb3+/Er3+/Na+ tridoped UCNCs with highly improved crystallinity and thus greatly enhanced UCL intensity are obtained. Moreover, these resulting UCNCs display abnormal thermal enhancement of UCL over a temperature range from 333 to 493 K, enabling the fabrication of supersensitive luminescent nanothermometers for temperature sensing. Based on the luminescence intensity ratio of two nonthermally coupled levels (i.e., 4F9/2 and 2H11/2) of Er3+, the as‐prepared Cs2ZrF6:Yb/Er/Na UCNCs exhibit an extremely large absolute sensitivity of 177.3% K−1 and a considerably high relative sensitivity of 1.52% K−1 at 333 K. These results unambiguously demonstrate that Cs2ZrF6 is a suitable host material for preparing small‐sized Ln3+‐doped UCNCs as nanothermometer for high‐performance ratiometric temperature sensing.

Tailoring crystalline Mn5O8 nanostructures: Kinetic control and stabilization for enhanced electrocatalytic O2 evolution

The stabilization of manganese oxide nanostructures with tunable oxidation states and morphologies is crucial for regulating catalytic properties. In this study, we aim to stabilize the metastable monoclinic Mn5O8 phase and control the morphology of the Mn5O8 nanostructures using a hydrothermal assisted calcination process in the presence of different precipitating agents. Raman experiments confirmed that the interaction of aqueous Mn2+ salts with different precipitating agents such as NaOH, ammonia, and oleylamine, resulted in the formation of Mn5O8. On the other hand, the precipitation of Mn2+ salt using diammonium oxalate monohydrate as a precipitating agent led to complete oxidation forming Mn2O3. Detailed phase and microstructural analyses were conducted using PXRD, XPS, and FESEM. The analyses revealed the formation of the monoclinic Mn5O8 phase with various morphologies, including hexagonal nanoplates, nanorods, and random nanoplates, when using NaOH, ammonia, and oleylamine as precipitating agents. The synthesized Mn5O8 phase was deposited onto an iron sheet as a substrate. Furthermore, we demonstrated the effect of the structure, morphology, and size of the Mn5O8 material on O2 evolution activity. The catalytic performance of irregularly shaped Mn5O8 nanoplates showed significantly lower η10 (270 mV) and η50 (350 mV) compared to Mn5O8 hexagonal nanoplates, Mn5O8 nanorods, and Mn2O3 nanostructure. Additionally, an insight into the catalytic performance was investigated in detail by evaluating electrochemical active sites, impedance spectroscopy, and hydrophilicity/hydrophobicity of the Mn5O8 material.

3D-Printed Eosin Y-Based Heterogeneous Photocatalyst for Organic Reactions.

Heterogenization of Eosin Y by 3D-printing and its application in photocatalysis are reported. The approach allows a fine tuning of the photocatalyst morphology and its rapid preparation. Photocatalytic activity was evaluated through model organic reactions involving oxidation, reduction, and photosensitization pathways. The efficiency, recyclability and stability of 3D printed EY is remarkable paving the way to new generation of heterogeneous photocatalysts with a perfect control of their shape and adaptable to any photoreactors.

Nanomaterials for co‐immobilization of multiple enzymes

AbstractIn order to co‐immobilize multiple enzymes, a wide range of nanomaterials has been designed to achieve synergistic enzyme activity and enhance catalytic efficiency. Nanomaterials, as carriers for enzyme co‐immobilization, possess various advantages such as tunable morphology and size, high specific surface area, and abundant chemically active sites. They can significantly enhance enzyme stability, activity, and catalytic efficiency. We overview the commonly used methods and strategies of enzyme co‐immobilization. This review further summarizes the latest research advances in nanomaterials for enzyme co‐immobilization applications over the past 5 years. Meanwhile, the advantages and challenges of these nanomaterials used for enzyme co‐immobilization as well as some potential future directions are also discussed.

Nanostructured ZnO with Tunable Morphology from Double-Salt Ionic Liquids as Soft Template.

ZnO nanostructures with tunable morphology were synthesized by the hydrothermal method from two ionic liquids (ILs), 1-ethyl-3-methylimidazolium acetate [C2mim]CH3CO2 and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C2mim](CF3SO2)2N and their corresponding double-salt ILs (DSILs). ILs served as soft templates. DSILs were noted for the production of smaller particle size along with uniformity compared to their pure IL counterparts. A changeover of the shape of ZnO from nano-prism to a hexagonal disk-like structure was observed with the addition of [C2mim]CH3CO2 in the medium during synthesis while nano-dice- and rod-shaped particles were obtained from [C2mim](CF3SO2)2N. The effect of concentration of both ILs was explored for the variations of size and shape, and at high concentrations, the morphology was distinct and sharp with uniform size in each case. The synthesized products exhibited excellent phase (wurtzite) purity and polycrystalline nature. The smallest crystallite size was acquired from DSILs, indicating the advantageous effect of the dual anions. The selective adsorption effect of [C2mim]CH3CO2 on certain facets promoted the growth of ZnO clusters along the [1010] direction, while [C2mim](CF3SO2)2N favored the growth along the [0001] direction. Consequently, DSILs rendered interpenetrating hexagonal disks due to the combined action of the anions for controlling the shape. The band gap energies of the nanoparticles (NPs) were consistent with the distribution of size. Extremely strong red emission and negligible UV emission for the synthesized ZnO NPs demonstrate their potential in the advancement of optoelectronic devices.

Molybdenum disulfide nanostructure grown on multi-walled carbon nanotube for the electrochemical detection of ofloxacin

The nanocomposite of molybdenum disulfide and carbon nanomaterials are gaining interest due to their tunable morphology and wide applications. This study has focused on exploring the unique structure of the present nanocomposite and its application toward sensing ofloxacin. The successful synthesis of nanocomposite with unique three-dimensional morphology and chemical integrity was confirmed through FESEM, HRTEM, XPS, XRD and Raman spectroscopy. The conductivity and selectivity of nanocomposite toward ofloxacin were explored through electrochemical applications. This study has also observed the behavior of pure ofloxacin and market drug ofloxacin in laboratory and real environment. For the real application, the drug ofloxacin was tested in rain, tap, and distilled water, and the sensitivity of the sensor in these sources was estimated. The sensitivity study was validated through differential pulse normal voltammetry and linear sweep voltammetry. This non-noble metal and the carbon-based hybrid composite has shown successful growth and holds a promising solution as a sensor for ofloxacin.

Construction of chitosan-gelatin polysaccharide-protein composite hydrogel via mechanical stretching and its biocompatibility in vivo

Natural polysaccharides and protein macromolecules are the important components of extracellular matrix (ECM), but individual component generally exhibits weak mechanical property, limited biological function or strong immunogenicity in tissue engineering. Herein, gelatin (Gel) was deposited to the stretched (65 %) chitosan (CS) hydrogel substrates to fabricate the polysaccharide-protein CS-Gel-65 % composite hydrogels to mimic the natural component of ECM and improve the above deficiencies. CS hydrogel substrates under different stretching deformations exhibited tunable morphology, chemical property and wettability, having a vital influence on the secondary structures of deposited fibrous Gel protein, namely appearing with the decreased β-sheet content in stretched CS hydrogel. Gel also produced a more homogenous distribution on the stretched CS hydrogel substrate due to the unfolding of Gel and increased interactions between Gel and CS than on the unstretched substrate. Moreover, the polysaccharide-protein composite hydrogel possessed enhanced mechanical property and oriented structure via stretching-drying method. Besides, in vivo subcutaneous implantation indicated that the CS-Gel-65 % composite hydrogel showed lower immunogenicity, thinner fibrous capsule, better angiogenesis effect and increased M2/M1 of macrophage phenotype. Polysaccharide-protein CS-Gel-65 % composite hydrogel offers a novel material as a tissue engineering scaffold, which could promote angiogenesis and build a good immune microenvironment for the damaged tissue repair.

Electroplated Electrodes for Continuous and Mass-Efficient Electrochemical Hydrogenation.

Electrocatalytic hydrogenations (ECH) enable the reduction of organic substrates upon usage of electric current and present a sustainable alternative to conventional processes if green electricity is used. Opposed to most current protocols for electrode preparation, this work presents a one-step binder- and additive-free production of silver- and copper-electroplated electrodes. Controlled adjustment of the preparation parameters allows for the tuning of catalyst morphology and its electrochemical properties. Upon optimization of the deposition protocol and carbon support, high faradaic efficiencies of 93 % for the ECH of the Vitamin A- and E-synthon 2-methyl-3-butyn-2-ol (MBY) are achieved that can be maintained at current densities of 240 mA cm-2 and minimal catalyst loadings of 0.2 mg cm-2, corresponding to an unmatched production rate of 1.47 kgMBE gcat -1 h-1. For a continuous hydrogenation process, the protocol can be directly transferred into a single-pass operation mode giving a production rate of 1.38 kgMBE gcat -1 h-1. Subsequently, the substrate spectrum was extended to a total of 17 different C-C-, C-O- and N-O-unsaturated compounds revealing the general applicability of the reported process. Our results lay an important groundwork for the development of electrochemical reactors and electrodes able to directly compete with the palladium-based thermocatalytic state of the art.