1D Nanostructures Research Articles

Studying the Effect of Oxidation on the Thermolysis of (NH4)2WS4 with In‐ and Ex‐Situ Electron Microscopy

AbstractThermolysis is a common technique in materials synthesis; however, oxidation of precursors used in these processes destroys the ability to generate end‐products with the desired composition and structure. Herein, the effects of oxidation on the thermolysis of (NH4)2WS4, a common precursor in the production of WS2 films, are studied utilizing electron microscopy. Specifically, in situ bright field, dark field, and secondary electron images were collected during heating of the aforementioned oxidized precursor from RT to 800 °C in 100 °C steps within a low kV scanning transmission electron microscope. These imaging results detail how the precursor transforms from its largely nondescript room temperature morphology to one having well formed 2D, 1D, and 0D nanostructures. Subsequent ex situ atomic level imaging shows that the 2D and 1D nanomaterials are composed of δ‐WO3 which has grown along its c‐axis, whereas the 0D nanoparticles are made solely of α‐W. Through the combination of both in and ex situ images, we have gained valuable insights into the structural and chemical changes that occur owing to the additional oxygen in the system, as well as the role that precursor density plays on the formation of these as formed nanomaterials.

Flower-like superstructure of boron carbon nitride nanosheets with adjustable band gaps for photocatalytic hydrogen peroxide production

The self-assembly of two-dimensional (2D) semiconductor nanosheets into three-dimensional (3D) ordered superstructures represents an ingenious way to avoid aggregation, expose massive available active sites and benefit the mass transfer, which maximizes the advantages of the 2D nanostructures in photocatalysis. Herein, a flower-like superstructure of ternary semiconducting boron carbon nitride nanosheets (FS-BCNNSs) was synthesized through the morphology-preserved thermal transformation of a flower-like superstructure of boron-containing metal-organic framework nanosheets (FS-MOFNSs). Taking advantage of this functional superstructure, FS-BCNNSs was employed for the pioneering application in the field of photocatalytic hydrogen peroxide (H2O2) production and exhibited excellent photocatalytic performance, yielding an impressive rate of 1415.9 μmol g−1 h−1 for the production of H2O2. The results of this work offer not just a promising catalyst for photocatalytic H2O2 production but also a facile strategy to fabricate unique superstructures constructed from 2D nanosheets for catalysis, energy conversion, and other related fields.

Design of bifunctional 1D nanostructures for the catalytic conversion of carbon dioxide into cyclic carbonates

One dimensional silica-based nanotubes represent an innovative and promising morphology in the context of heterogeneous catalysis. Here these nanostructures were prepared for the first time as bifunctional materials, with hafnium or tin atoms inserted as single sites in the silica structure and imidazolium moieties anchored at the surface. The low dimensional solids thus present both acid sites owing to the presence of metal cations in tetrahedral coordination (co-catalyst) and nucleophilic species coming from the counterion of the imidazolium moieties (catalyst). The design of the catalysts consisted of two main steps. The Hf- or Sn-doped silica solids were initially prepared using a straightforward sol-gel method including a pH adjustment step allowing a quantitative insertion of the metal cations in the silica framework. These materials were post-functionalized with imidazolium moieties. The solids were extensively characterized thus confirming the presence of well-defined and open tubular structure, high specific surface area, successful insertion of Hf and Sn in the silica framework, and a correct functionalization with imidazolium salts. The different catalysts were tested in the valorization of CO2 with styrene oxide to give the corresponding cyclic carbonate. The bifunctional solids were stable and recyclable. The versatility of the best catalyst, represented by the Hf-based material, was confirmed using different epoxides. Finally, by tuning the reaction conditions or changing the imidazolium salt, a further boost of the catalytic performances was achieved.

Molecular dipole regulated surface potential and ferroelectric characteristics in nanoconfined P(VDF-TrFE) architectures

Molecular dipole orientation is crucial to efficiently utilize the piezo- and ferroelectric polarization in polymers. Modern electronic applications of these polymer demand switching of dipoles with low voltage, which requires the dipole orientation to be perpendicular to the substrate (edge-on) rather than parallel (face-on). The 0D, 1D and 2D confinement of polymer architectures into nanoparticles, nanofibers, and thin films is a vital approach to control dipole orientation in ferroelectrics. Our findings show that for 1D (d33 ∼ 18 ± 2.2 pm/V) and 2D nanostructures (d33 ∼ 15 ± 1.5 pm/V) of poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)), the molecular dipoles are edge-on, whereas for 0D, the dipoles are face-on, which would govern the ferroelectric and piezoelectric behaviour of these confined structures. The subsequent observation concludes that altering the dipole orientation allows precise modulation of surface potential and work function. The work functions of the 0D, 1D and 2D nanostructures are 4.56 ± 0.03 eV, 4.93 ± 0.51 eV and 4.68 ± 0.18 eV, respectively. The tunability of surface potential opens up the possibility of utilizing these nanostructures in single-material triboelectric series. Density functional theory (DFT)-based computations substantially support these experimental findings. This study provides a thorough understanding of the effect of molecule dipole orientation on piezo- and ferroelectric properties of P(VDF-TrFE) nanostructures.

High-efficiency recyclable reduced graphene oxide-tin oxide nanocomposite catalyst for esterification

Graphene oxide (GO) possesses 2D nanostructures and was synthesized indigenously via the enhanced Hummer method. It is well-accepted that the redox approach is a distinctive technique to fabricate GO on an expanded scale. Here, reduced graphene oxide-tin oxide (SnO2-rGO) nanocomposite material was produced for application as an efficient heterogeneous solid acid catalyst esterification reaction. Fourier transform infrared analysis was carried out to validate the incidence of oxygen functional groups in GO and SnO2-rGO nanocomposite. The Raman spectra of GO and SnO2-rGO nanocomposite have been simulated to get stable structure and functional groups. To get surface morphological and structural features, powder X-ray diffraction, scanning electron microscope-energy dispersive X-ray spectra, transmission electron microscope and high resolution-TEM analysis, and thermogravimetric analysis were delineated during this experimental study. It is seen that the catalyst has high efficiency for esterification reaction. The maximum efficiency (96% yield) was obtained when a 1:3 (acetic acid to benzyl alcohol) molar ratio, catalyst (25 mg), temperature (60 0C), and time (4 h) were maintained. The SnO2-rGO nanocomposite was recycled several times with a minimal loss of its efficiency.

Nickel modified TiO2/C nanodisks with defective and near‐amorphous structure for high‐performance sodium‐ion batteries

AbstractLow‐cost sodium‐ion batteries (SIBs) are the star products in grid‐scale energy storage applications. Finding befitting anode materials is crucial to the advancement of SIBs. In this study, a novel two‐dimension (2D) nanostructured anode material composed of TiO2/C nanodisks and Ni nanoparticles that were synthesized by a facile metal‐organic frameworks derived method is reported. By introducing divalent Ni2+ ions in the synthesis process, TiO2/C microblocks were successfully transformed into the desirable 2D nanodisks, enabling the active materials to be more efficiently and fully utilized due to short diffusion path and substantive exposed active sites. Another important role of Ni2+ ions is as a doping source for TiO2, resulting in the formation of a defective and near‐amorphous TiO2/C structure, which aids in improving the kinetics. In addition, some Ni nanoparticles formed and attached to the surface of the TiO2/C nanodisks, which not only act as conductive bridges to make all the nanodisks electrically active but also act as pillars to prevent them from stacking. This unique 2D nanostructured anode material manifests high reversible capacities, excellent cycle performance, and impressive rate capability. This work provides a new means for the controllable synthesis of 2D nanostructured materials for energy storage applications.

Pillar Growth by Focused Electron Beam-Induced Deposition Using a Bimetallic Precursor as Model System: High-Energy Fragmentation vs. Low-Energy Decomposition.

Electron-induced fragmentation of the HFeCo3(CO)12 precursor allows direct-write fabrication of 3D nanostructures with metallic contents of up to >95 at %. While microstructure and composition determine the physical and functional properties of focused electron beam-induced deposits, they also provide fundamental insights into the decomposition process of precursors, as elaborated in this study based on EDX and TEM. The results provide solid information suggesting that different dominant fragmentation channels are active in single-spot growth processes for pillar formation. The use of the single source precursor provides a unique insight into high- and low-energy fragmentation channels being active in the same deposit formation process.

Spectral Tuning of Plasmonic Activity in 3D Nanostructures via High‐Precision Nano‐Printing

AbstractPlasmonic nanoparticles reveal unique optical properties and are increasingly incorporated into commercial products and technologies, ranging from photovoltaics to biological and chemical sensors. Shifting and tuning their plasmonic response according to the targeted application strongly depends on the ability to control the geometry in every detail and has not been reliably demonstrated for complex 3D nano‐architectures yet. Following that motivation, it herein presents how Focused Electron Beam Induced Deposition (FEBID), a highly flexible additive 3D direct‐write technology with spatial nano‐scale precision, is used for the controlled and tunable fabrication of plasmonically active 3D nanostructures that exhibit highly concentrated, well defined and predictable local plasmonic resonances. As model systems, planar Au nanowires and 3D nano‐tips of various geometries are prepared via FEBID and plasmonically characterized via scanning transmission electron microscopy based electron energy loss spectroscopy (STEM‐EELS) mapping measurements. The findings are complemented with corresponding plasmon simulations, revealing very good agreement with experimental findings. This way, on‐demand spectral tuning of the plasmonic response becomes accessible via upfront modeling and design of suitable 3D nanostructures, to achieve customized plasmonic responses, therefore paving the way for yet unrealized plasmonic applications in 3D space.

Mathematical Modeling of Propagation and Diffraction of Microwaves in Anisotropic Magnetic Nanocomposites and 3D Nanostructures Based on Opal Matrices

Mathematical Modeling of Propagation and Diffraction of Microwaves in Anisotropic Magnetic Nanocomposites and 3D Nanostructures Based on Opal Matrices

Construction of PVC/PVA WO3 3D Nanostructure Thin Film Nanocomposite for Treatment of Oil Refinery Wastewater

Construction of PVC/PVA WO3 3D Nanostructure Thin Film Nanocomposite for Treatment of Oil Refinery Wastewater

Plasmonic Modification of Epitaxial Nanostructures for the Development of a Highly Efficient SERS Platform

Epitaxy is the process of crystallization of monocrystalline layers and nanostructures on a crystalline substrate. It allows for the crystallization of various semiconductor layers on a finite quantity of semiconductor substrates, like GaAs, InP, GaP, InGaP, GaP, and many others. The growth of epitaxial heterostructures is very complicated and requires special conditions and the precise control of the growth temperature, the pressure in the reactor, and the flow of the precursors. It is used to grow epitaxial structures in lasers, diodes, detectors, photovoltaic structures, and so on. Semiconductors themselves are not suitable materials for application in surface-enhanced Raman spectroscopy (SERS) due to poor plasmonic properties in the UV/VIS range caused by missing free electrons in the conduction band due to the existing band gap. A plasmonic material is added on top of the nanostructured pattern, allowing for the formation of mixed photon–plasmon modes called localized surface plasmon-polaritons which stand behind the SERS effect. Typically, gold and silver are used as functional plasmonic layers. Such materials could be deposited via chemical or physical process. Attention has also been devoted to other plasmonic materials, like ones based on the nitrides of metals. The SERS performance of a functional surface depends both on the response of the plasmonic material and the morphology of the underlying semiconductor epitaxial layer. In the context of SERS, epitaxial growth allows for the fabrication of substrates with well-defined 3D nanostructures and enhanced electromagnetic properties. In this work, we described the possible potential plasmonic modification, composed of various coatings such as noble metals, TiN, and others, of well-developed epitaxial nanostructures for the construction of a new type of highly active SERS platforms. This abstract also highlights the role of epitaxial growth in advancing SERS, focusing on its principles, methods, and impact. Furthermore, this work outlines the potential of epitaxial growth to push the boundaries of SERS. The ability to design substrates with tailored plasmonic properties opens avenues for ultralow concentration detection.

Tuning the bandgap of 2D metallic Zn nanostructures

The semiconducting behavior of two-dimensional (2D) metal nanostructures has recently attracted much interest for their possible applications in optoelectronics and others. In particular, tuning the bandgap of such nanostructures can open up a new avenue for fabricating functional nano-devices. In the present article, we report the synthesis of 2D metallic Zn nanosheets at room temperature using a ball mill, which is capable of producing large-scale materials in a single run. Initially, nanoplates were formed for ball milling the octahedral-shaped Zn nanoparticles for the time of milling of 6 h. Subsequent ball milling for another 6 h leads these nanoplates to nearly uniform nanosheets. The thickness of these 2D nanostructures was found to decrease with an increase in the time of milling. Visible photoluminescence (PL) emissions centered at ∼3, ∼2.9, and ∼2.75 eV were observed from all the Zn particles showing semiconductor behavior. The origin of such semiconductor behavior was explained based on the radiative transition of electrons from the sp band to the upper states of the 3d band. This argument was confirmed through the studies of photoelectron spectroscopy and the first principle calculations employing density functional theory (DFT). Furthermore, excitation-dependent PL studies indicated that the bandgap of the 2D Zn nanostructures decreased with the increase in the ball milling time. Therefore, a redshift in the bandgap was observed with the increase in the ball milling time. Such changes in the bandgap with the thickness of 2D Zn nanostructures were also verified from the studies of DFT. Thus, the present study demonstrated that the bandgap of 2D metallic Zn nanostructures could be effectively tuned by reducing the thickness.

Wearable Nano-Based Gas Sensors for Environmental Monitoring and Encountered Challenges in Optimization.

With a rising emphasis on public safety and quality of life, there is an urgent need to ensure optimal air quality, both indoors and outdoors. Detecting toxic gaseous compounds plays a pivotal role in shaping our sustainable future. This review aims to elucidate the advancements in smart wearable (nano)sensors for monitoring harmful gaseous pollutants, such as ammonia (NH3), nitric oxide (NO), nitrous oxide (N2O), nitrogen dioxide (NO2), carbon monoxide (CO), carbon dioxide (CO2), hydrogen sulfide (H2S), sulfur dioxide (SO2), ozone (O3), hydrocarbons (CxHy), and hydrogen fluoride (HF). Differentiating this review from its predecessors, we shed light on the challenges faced in enhancing sensor performance and offer a deep dive into the evolution of sensing materials, wearable substrates, electrodes, and types of sensors. Noteworthy materials for robust detection systems encompass 2D nanostructures, carbon nanomaterials, conducting polymers, nanohybrids, and metal oxide semiconductors. A dedicated section dissects the significance of circuit integration, miniaturization, real-time sensing, repeatability, reusability, power efficiency, gas-sensitive material deposition, selectivity, sensitivity, stability, and response/recovery time, pinpointing gaps in the current knowledge and offering avenues for further research. To conclude, we provide insights and suggestions for the prospective trajectory of smart wearable nanosensors in addressing the extant challenges.

Highly Deformable Double‐Sided Neural Probe with All‐in‐One Electrode System for Real‐Time In Vivo Detection of Dopamine for Parkinson's Disease

AbstractPrecise monitoring of neurotransmitters, such as dopamine (DA), is critical for understanding brain function and treating neurological disorders since dysregulation of DA implicates in a range of disorders, including Parkinson's disease (PD), schizophrenia, and addiction. This study proposes a multi‐deformable double‐sided (MDD) DA‐sensing probe with the three‐electrode system in all‐in‐one form for reliable real‐time monitoring of DA dynamics by integrating working, reference, and counter electrodes on a single probe. The proposed probe achieves high DA sensitivity and selectivity in virtue of enzyme immobilization on the 3D nanostructures grown on working electrode. Also, the serpentine design is employed for the electrodes to withstand in various deformations by achieving high stretchability and manage the stress induced on the probe. Experimental and computational analysis demonstrates an effective reduction in induced‐stress on the electrodes. The MDD DA‐sensing probe is implanted into the brain with success to enable real‐time, in vivo monitoring of DA levels in rodents. Furthermore, DA dynamic changes are monitored before and after treatment with L‐DOPA in hemi‐PD mice. This extremely deformable implantable probe has the potential for use in the study and treatment of neurodegenerative diseases, providing reliable monitoring of DA dynamics with minimal damage to brain tissue.

Engineering of Micro-mesoporous two-dimensional CeO2-based heterojunction oxides for energy storage applications

With growing demands on energy supply and storage, there is a need for advanced devices that can meet the high power and energy requirements. One such device is a supercapacitor, which is classified into two types, namely the electrical double-layer capacitor (EDLC) and the pseudocapacitor. Pseudocapacitors show energy storage properties that are between EDLCs and batteries and generally, transition metal oxides are used for these applications. Recent work has demonstrated that CeO2 is a potential material for such applications owing to its reversible charge-switching capabilities and good stability in different environments. In the present work, novel ultrathin nanosheets of CeO2-x and a composite of ruthenium (Ru)-CeO2-x, with the Ru in the form of mixed heteroatoms and dopants were synthesised using a Ce-based coordination polymer (Ce-CP) as the precursor using modified anodic chronoamperometric electrodeposition (MACE) technique. The ready exfoliation of Ce-CP in triethanolamine, which was the exfoliation medium, followed by solvent removal and annealing at 300 °C resulted in the formation of ultrathin 2D CeO2 nanosheets that are partially stacked, resulting in the formation of flower-like 3D nanostructures. The ultrathin 2D CeO2 formed 3D flower-like nanostructures with high concentrations of defects, active sites, and mesopores, which increased with the concentration of Ru in the CeO2-x nanostructure. Additionally, the specific surface area of the Ru-CeO2-x samples was higher, increasing to 354 m2·g−1 compared to the value of 146 m2·g−1 for pristine CeO2-x. The cyclic voltammetry analysis revealed that the introduction of Ru increased the capacitance of pristine CeO2-x from 665 F·g−1 to 923 F·g−1 at a scan rate of 5 mV·s−1. These findings suggest that Ru-CeO2-x nanosheets have potential for use in supercapacitor applications.

A review on polymeric nanocomposites for the electrochemical sensing of breast cancer biomarkers

Breast cancer is a rapidly spreading disease and early detection of associated biomarkers in body fluids, particularly blood, is crucial. Electrochemical biosensors, known for their high sensitivity, selectivity, cost-effectiveness, and miniaturization potential, have emerged as a promising tool for breast cancer screening. This review article focuses on the integration of polymers and nanosized objects to enhance the performance of electrochemical biosensors in analyzing breast cancer biomarkers in serum samples, breast cancer cell lysates, and tumor tissues. Recent developments in this field have demonstrated the significant benefits of these sensors, including improved sensitivity and selectivity. By incorporating nanocomposites into the electrochemical sensing interface, signal amplification is achieved, resulting in enhanced detection limits and accuracy. The use of different dimensionalities of nanomaterials (0D, 1D, 2D, and 3D nanostructured interfaces) in polymer-based nanocomposites has further contributed to the development of sensors with unique properties for sensitive and rapid detection. The potential of electrochemical biosensors based on polymer nanocomposites to revolutionize disease management lies in their ability to enable user-friendly breast cancer screening and facilitate early detection. However, there are still limitations that need to be addressed, and further research is required to optimize the performance of these sensors. The article also discusses the future perspectives and real-world applications of electrochemical biosensors based on polymer nanocomposites while considering the challenges that lie ahead.

0D, 1D, and 2D magnetic nanostructures: Classification and their applications in modern biosensors

Magnetic nanomaterials have emerged as versatile platforms that offer unique advantages in various biomedical applications. With the incorporation of magnetic nanomaterials, which include zero-dimensional (0D), one-dimensional (1D), and two-dimensional (2D) variants, the field of biosensors is rapidly expanding. This review examines the properties, role, and functionalization of 0D, 1D, and 2D magnetic nanomaterials and highlights their distinct advantages in improving the selectivity, limit of detection (LOD), and specificity in biosensing applications. This article also emphasizes magnetic properties and magnetism-based approaches utilized in the arena of magnetic nanomaterials-based biosensors. In addition, the review covers the recent advances and developments in the integration of magnetic nanomaterials (0D, 1D, and 2D) with various electrochemical, optical, and magnetic-based biosensing techniques for the detection of various biomolecules, pathogens, and diagnosis of numerous diseases.

Biomedical Applications of 2D MXene Nanocomposites: A Review

AbstractBiomaterials technology has advanced significantly in recent years and 2D nanostructures have played a key role in this advancement. A new ceramic 2D nanomaterial, MXene, made up of transition metal carbides, carbonitrides and nitrides with a planar layout that was produced by etching away “A” from a ceramic phase called “MAX”, has emerged to overcome the shortcomings of traditional biomaterials. MXene is used inadequately in biomedical applications due to its weak stability in physiological conditions, lack of prolonged and low biodegradability, and self‐controlled drug release. These drawbacks have given rise to the idea of using MXene/Polymer nano composites, due to their major properties like large surface area, metallic conductivity, biocompatibility, hydrophilicity, and size tunability. Polymer functionalization is possible by the surface‐available functional groups. This review has been done to focus on cutting‐edge examples such as polymer functionalized composites MXene for the developing field of biomedical applications. These applications consist of precise and prolonged antimicrobial activity, bio sensing, therapeutics, drug delivery, contrast‐enhanced diagnostic imaging, tissue engineering, flexible electronics, and bone regeneration.

Cactus-like (Ni,Co)Se2 nanosheets with 3D structure decorated on the conductive substrate for efficient hydrogen evolution reaction

Transition metal selenides are a fascinating class of substitute for traditional noble metal electrocatalysts for hydrogen evolution reaction (HER). However, the monometallic selenides still have the disadvantages of low electroactive sites and electrical conductivity. To address such drawbacks, three-dimensional (3D) hierarchical nanostructures composed of bimetallic compounds have aroused great attention. In this study, cactus-like bimetallic nickel–cobalt nanosheets with a 3D nanostructure are successfully prepared on the surface of conductive substrate by a one-step hydrothermal reaction. Then a high-efficiency bimetallic catalyst ((Ni,Co)Se2/CFP) is obtained by a facile chemical vapor deposition. Benefiting from bimetallic components and the unique 3D structure, the cactus-like (Ni,Co)Se2/CFP only requires a low overpotential of 154 mV to reach the current density of 10 mA cm−2. The Tafel slope of (Ni,Co)Se2/CFP (67 mV dec−1) further shows that (Ni,Co)Se2/CFP has faster HER kinetics. Besides, the long-term stability test demonstrates the excellent durability of (Ni,Co)Se2/CFP in 0.5 M H2SO4. This research offers a useful technique and guide for improving the structure of bimetallic selenides based on transition metals to design high-efficient HER electrocatalysts.

Rational design of a CoFe-prussian blue analogue-derived three-dimensional ternary nanocatalyst with efficient ORR/OER catalytic performance for Zn-air batteries

To effectively alleviate the aggregation of catalytic active sites, the rational design and simple preparation of a nanocatalyst with an ideal configuration plays a decisive role. Herein, a CoFe-prussian blue analogue (PBA) decorated with composite carbon/nitrogen sources (C/Ns) is prepared as the precursor to synthesize a three-dimensional (3D) ternary nanocomposite by a two-step calcination method. In this 3D nanocomposite, the 0D CoFe alloy nanoparticles derived from the PBA are mostly embedded in 1D N-doped carbon nanotubes (NCNTs) and partially loaded on 2D N-doped carbon nanosheets. Accordingly, the aggregation of alloy nanoparticles is greatly alleviated while a 3D nanostructure with large specific surface area, porosity, good electron transport properties and exposed active sites can be formed. The alloy nanoparticles are excellent electrocatalysts for oxygen reduction/oxygen evolution reactions, while also facilitating the formation of conductive NCNTs. Density Functional Theory calculations confirm the synergy between the Fe, N doped carbon and (110) crystal plane of the CoFe alloy that accounts for the electrocatalytic activity. The assembled Zn-air batteries show an open circuit voltage of 1.510 V, power density of 196.1 mW cm−2 and an operational durability of 300 h. Moreover, the assembled all-solid-state batteries display the potential for practical applications. This work demonstrates that the configuration of the electrocatalyst can significantly affect its catalytic performance.