Fabrication Of Nanostructures Research Articles

Insights into the writing process of the mask-free nanoprinting fluid force microscopy technology

Platelets are activated immediately when contacting with non-physiological surfaces. Minimization of surface-induced platelet activation is important not only for platelet storage but also for other blood-contacting devices and implants. Chemical surface modification tunes the response of cells to contacting surfaces, but it requires a long process involving many regulatory challenges to transfer into a marketable product. Biophysical modification overcomes these limitations by modifying only the surface topography of already approved materials. The available large and random structures on platelet storage bags do not cause a significant impact on platelets because of their smallest size (only 1–3 μm) compared to other cells. We have recently demonstrated the feasibility of the mask-free nanoprint fluid force microscope (FluidFM) technology for writing dot-grid and hexanol structures. Here, we demonstrated that the technique allows the fabrication of nanostructures of varying features including grid, circle, triangle, and Pacman-like structures. Characteristics of nanostructures including height, width, and cross-line were analyzed and compared using atomic force microscopy imaging. Based on the results, we identified several technical issues, such as the printing direction and shape of structures that directly altered nanofeatures during printing. Importantly, both geometry and interspace governed the degree of platelet adhesion, especially, the structures with triangular shapes and small interspaces prevent platelet adhesion better than others. We confirmed that FluidFM is a powerful technique to precisely fabricate a variety of desired nanostructures for the development of platelet/blood-contacting devices if technical issues during printing are well controlled.

Graphene Quantum Dots as Hole Extraction and Transfer Layer Empowering Solar Water Splitting of Catalyst-Coupled Zinc Ferrite Nanorods.

Despite the narrow band gap energy, the performance of zinc ferrite (ZnFe2O4) as a photoharvester for solar-driven water splitting is significantly hindered due to its sluggish charge transfer and severe charge recombination. This work reports the fabrication of a hybrid nanostructured hydrogenated ZnFe2O4 (ZFO) photoanode with enhanced photoelectrochemical water-oxidation activity through coupling N-doped graphene quantum dots (GQDs) as a hole transfer layer and Co-Pi as a catalyst. The GQDs not only reduce the surface-mediated nonradiative electron-hole pair recombination but also induce a built-in interfacial electric field leading to a favorable band alignment at the ZFO/GQDs interface, helping rapid photogenerated hole separation and serving as a conducting hole transfer highway, improve the hole transportation into the Co-Pi catalyst for enhanced water oxidation reaction kinetics. The optimized ZFO/GQD/Co-Pi hybrid photoanode delivers a 23-fold photocurrent enhancement at 1.23 V versus the reversible hydrogen electrode (RHE) and a significant 360 mV reduction in the onset potential, reaching 0.65 VRHE compared with the ZFO photoanode under 1 sun illumination in a neutral electrolytic environment. This investigation underscores the mechanism of synergistic interplay between the hole transport layer and cocatalyst in boosting the solar-illuminated water-splitting activity of the ZFO photoanode.

Revealing the Influence of Molecular Chemisorption Direction on the Reaction Selectivity of Dehalogenative Coupling on Au(111): Polymerization versus Cyclization.

The control of reaction selectivity is of great interest in chemistry and depends crucially on the revelation of key influencing factors. Based on well-defined molecule-substrate model systems, various influencing factors have been elucidated, focusing primarily on the molecular precursors and the underlying substrates themselves, while interfacial properties have recently been shown to be essential as well. However, the influence of molecular chemisorption direction on reaction selectivity, as a subtle interplay between molecules and underlying substrates, remains elusive. In this work, by a combination of scanning tunneling microscopy imaging and density functional theory calculations, we report the influence of molecular chemisorption direction on the reaction selectivity of two types of dehalogenative coupling on Au(111), i.e., polymerization and cyclization, at the atomic level. The diffusion step of a reactive dehalogenated intermediate in two different chemisorption directions was theoretically revealed to be the key to determining the corresponding reaction selectivity. Our results highlight the important role of molecular chemisorption directions in regulating the on-surface dehalogenative coupling reaction pathways and products, which provides fundamental insights into the control of reaction selectivity by exploiting some subtle interfacial parameters in on-surface reactions for the fabrication of target low-dimensional carbon nanostructures.

An outstanding photocatalytic performance of CNTs based nanocomposite of ternary metal oxides towards cationic and anionic dyes and pharmaceutical drug

Currently, hetero-metallic oxides and their nanocomposites with 1D materials have a tremendous role in photocatalytic applications, mainly for the removal of organic effluents, due to their higher potential of electron-hole pair migration and separation than pure metal oxide NPs. The present work reports the fabrication of ternary metal oxides nanostructure (WO3·Ag2O·CuO) and its nanocomposite with carbon nanotubes (WO3·Ag2O·CuO/CNTs) using a facile approach i.e. ultra-sonication. The photocatalytic removal efficacy of fabricated nanocomposite i.e. WO3.Ag2O.CuO/CNTs along its counterpart (WO3·Ag2O·CuO) was evaluated using a model cationic dye (Methylene blue, MB), an anionic dye (Congo red, CR), and an analgesic drug (Paracetamol). The catalytic experiment was performed under natural sunlight upon light irradiation of about 90 min and using 30 mg of photocatalyst for all chosen effluents. The obtained results deduced that WO3·Ag2O·CuO/CNTs nanocomposite showed catalytic efficiency of about 97 % for MB, 87 % for CR, and 93 % for Paracetamol while it was about 80 % for MB, 74 % for CR, and 79 % for drug using WO3·Ag2O·CuO as photocatalyst. The rate constant values of nanocomposite for the removal of MB, CR, and Paracetamol are 0.037 min−1, 0.023 min−1, and 0.027 min−1 respectively. The remarkable degradation performance of WO3·Ag2O·CuO/CNTs nanocomposite as compared to ternary metal oxide (WO3·Ag2O·CuO) was due to its high charge separation, high surface area, and availability of large number of active sites for the adsorption of pollutant molecules. Hence, WO3·Ag2O·CuO/CNTs nanocomposite could be a competent photocatalyst for the removal of variety of industrial effluents i.e. organic dyes and pharmaceutical drugs etc.

Self‐assembly of Polyoxometalate Clusters into Nanostructures with Different Dimensions

Self‐assembly of polyoxometalate (POM) clusters offers a viable method for constructing nanostructures with tailored properties. Over the past few decades, POMs‐based nanostructures of varying dimensions, such as nanowires, nanobelts, nanosheets, and other superstructures, have been constructed. Additionally, these nanostructures show broad prospects in optical, electrochemical, catalytic, and mechanical applications. Particularly noteworthy are surface modifications, such as surfactant encapsulation, which yield amphiphilic POMs. These modifications render the POMs compatible with organic systems, significantly broadening their morphological and functional applicability. This concept provides an overview of recent advancements in nanostructures based on self‐assembly of surfactant encapsulated POM clusters, encompassing one‐dimensional (1D), two‐dimensional (2D), and three‐dimensional (3D) structures. Through surfactant encapsulation, POM clusters can be rendered compatible with various solvents, facilitating the formation of hybrid assemblies with diverse morphologies and unique properties. The structures, formation mechanisms, and properties of these sub‐nanometer assemblies are discussed from both experimental and theoretical perspectives. This concept aims to provide a new insight into the design and fabrication of nanostructures based on POM clusters.

Conventional sintering of nano-crystalline Yttria-Stabilized Zirconia enables high-strength, highly translucent and opalescent dental ceramics

Development of restorative materials capable of mimicking optical and mechanical performance of natural teeth is a quest in aesthetic density. Yttria-Stabilized Zirconia (YSZ) ceramics represent one of the most popular choices for dental restorations, owing to their biocompatibility, white colour, and the possibility to use CAD-CAM technologies. In particular, YSZ doped with 3 mol. % yttria (3YSZ) is popular because it presents high strength. Nonetheless, the limited light transmission of commercially available high strength 3YSZ does not meet the requirements of highly aesthetic cases. On the other side, YSZ presenting a larger portion of yttria are more translucent but exhibit modest strength. Here, we report on fabrication of dense zirconia nanostructures in bulk form via conventional pressure-less sintering at temperatures down to 1100–1200 °C, achieving highly translucent and strong 3YSZ with significant opalescent behaviour. Both Hall−Petch and inverse Hall-Petch relationship were observed in 3YSZ samples with average grain size in the range of 250 nm and 55 nm, demonstrating the importance of grain size control to enhance both optical and mechanical properties of zirconia ceramics, simultaneously. Maximum biaxial strength of 1980 ± 260 MPa, in-line light transmission of 38% in the visible spectrum and opalescence approaching that of enamel were obtained at optimum grain size of 80 ± 5 nm. The notable optical properties are linked to the miniaturization of the residual pores and refinement of grain size towards the nanoscale while the superior mechanical strength is justified by the activation of different energy dissipation processes at nano and macroscale.

Fabrication of porous copper oxide nanostructure on nickel foam electrode by a co-precipitation method for non-enzymatic glucose detection

A novel porous copper oxide nanostructure on nickel foam (CuO/NF) electrode has been successfully prepared through a co-precipitation way. The porous CuO structure and nickel foam can be integrated into a three-dimensional ordered and hierarchal CuO electrode sensor. The porous CuO structure contains many loosely packed nanoparticles and the nanochannels, which are beneficial for providing more active sites for electrocatalytic oxidation–reduction reactions. The Cu(III)/Cu(II) pair plays an essential role, which completes the charge transfer during the electrochemically catalyzed reaction. Two Cu(III) ions obtain two electrons from one molecule of glucose, which completes two electron transfers to produce one molecule of gluconic acid lactone. The results of the actual detection of Fetal Bovine Serum indicate that the CuO/NF electrode produced could be utilized for the determination of actual samples.

Fabrication of Nanostructures Consisting of Composite Nanoparticles by Open-Air PLD

We present a two-step physical method for the fabrication of composite nanoparticle-based nanostructures. The proposed method is based on the pulsed laser deposition (PLD) technique performed sequentially in vacuum and in air. As a first step, thin-alloyed films of iron with noble metal were deposited by PLD in vacuum. The films were prepared by ablation of a mosaic target formed by equal iron and gold sectors. As a second step, the as-prepared alloyed films were ablated in air at atmospheric pressure as the laser beam scanned their surface. Two sets of experiments were performed in the second step, namely, by applying nanosecond (ns) and picosecond (ps) laser pulses for ablation. The structure, microstructure, morphology, and optical properties of the samples obtained were studied with respect to the laser ablation regime applied. The implementation of the ablation process in open air resulted in the formation of nanoparticle and/or nanoparticle aggregates in the plasma plume regardless of the ablation regime applied. These nanoparticles and/or nanoaggregates deposited on the substrate formed a complex porous structure. It was found that ablating FeAu films in air by ns pulses resulted in the fabrication of alloyed nanoparticles, while ablation by ps laser pulses results in separation of the metals in the alloy and further oxidation of Fe. In the latter case, the as-deposited structures also contain core–shell type nanoparticles, with the shell consisting of Fe-oxide phase. The obtained structures, regardless of the ablation regime applied, demonstrate a red-shifted plasmon resonance with respect to the plasmon resonance of pure Au nanoparticles.

Surface engineering by rogue wave induced by energetic carbon clusters

Swift heavy ions are effective in nanostructuring material surfaces. The irradiation of lanthanum fluoride with 30 MeV C60 leads to the creation of surface nanohillocks of size larger than the ones produced by monoatomic heavy ions. The generation of the observed nano-sized hillocks is described here by a new approach that is based on ion-induced intensive electronic excitations that create localized rogue waves. Consequently, the induced nonlinear ion-acoustic rogue waves are considered a hallmark of nanohillock formation. Plasma hydrodynamic equations produce a relationship between normalised electron number density and crystal lattice spacing. Similarities to the hillock profile suggest the crucial primary role of electron density in the fabrication of surface nanostructures.

In situ fabrication of transition metal phosphide tree-like nanostructure for energy-saving hydrogen production coupled via urea oxidation reaction

Substituting the Oxygen Evolution Reaction (OER) with the Urea Oxidation Reaction (UOR) which is a thermodynamically more favorable option, has paved the way for the production of energy-saving hydrogen as well as the purification of urea-reach waste water. In this study, a nanostructured, porous and active Ni-Cu-Mn-P electrode was created using the dynamic hydrogen bubble template (DHBT) process in different conditions. The fabricated electrodes were utilized as bi-functional electrodes for both the HER and UOR processes. The electrochemical results displayed that the Ni-Cu-Mn-P (which synthesized at current density of 2 A.cm−2) requires only 84 mV overpotential to achieve a current density of 10 mA.cm−2, in HER process, and the necessary potential value for the UOR is only 1.30 V vs RHE. Also, the favorable electrocatalytic stability for industrial applications was also confirmed. The Ni-Cu-Mn-P electrode also demonstrated satisfactory performance in the overall urea electrolysis process and the cell voltage was 1.40 V to generate 10 mA.cm−2. The excellent performance of the electrode was due to the hierarchical porous nanostructure with high active surface area and also the synergistic effect between the elements. This study introduces an effective catalyst design for energy-saving hydrogen production.

Hierarchical Ni3V2O8@N-Doped Carbon Hollow Double-Shell Microspheres for High-Performance Lithium-Ion Storage.

Transition metal oxides (TMOs) are highly dense in energy and considered as promising anode materials for a new generation of alkaline ion batteries. However, their electrode structure is disrupted due to significant volume changes during charging and discharging, resulting in the short cycle life of batteries. In this paper, the hierarchical Ni3V2O8@N-doped carbon (Ni3V2O8@NC) hollow double-shell microspheres were prepared and used as electrode materials for lithium-ion batteries (LIBs). The utilization efficiency and ion transfer rate of Ni3V2O8 were improved by the hollow microsphere structure formed through nanoparticle self-assembly. Furthermore, the uniform N-doped carbon layer not only enhanced the structural stability of Ni3V2O8, but also improved the overall electrical conductivity of the composite. The Ni3V2O8@NC electrode has an initial discharge capacity of up to 1167.3 mAh g-1 at a current density of 0.3 A g-1, a reversible capacity of up to 726.5 mAh g-1 after 200 cycles, and still has a capacity of 567.6 mAh g-1 after 500 cycles at a current density of 1 A g-1, indicating that the material has good cycle stability and high-rate capability. This work presents new findings on the design and fabrication of complex porous double-shell nanostructures.

Recent Advances in Two-Dimensional Nanomaterials for Healthcare Monitoring.

The development of advanced technologies for the fabrication of functional nanomaterials, nanostructures, and devices has facilitated the development of biosensors for analyses. Two-dimensional (2D) nanomaterials, with unique hierarchical structures, a high surface area, and the ability to be functionalized for target detection at the surface, exhibit high potential for biosensing applications. The electronic properties, mechanical flexibility, and optical, electrochemical, and physical properties of 2D nanomaterials can be easily modulated, enabling the construction of biosensing platforms for the detection of various analytes with targeted recognition, sensitivity, and selectivity. This review provides an overview of the recent advances in 2D nanomaterials and nanostructures used for biosensor and wearable-sensor development for healthcare and health-monitoring applications. Finally, the advantages of 2D-nanomaterial-based devices and several challenges in their optimal operation have been discussed to facilitate the development of smart high-performance biosensors in the future.

Self-assembly plasmonic gold nanoribbons on few-layer PtSe2 under femtosecond laser irradiation

Functional two-dimensional (2D) materials have been extensively explored for a wide range of applications such as energy generation, low-power computing, and biosensing. In this work, we present an approach involving the integration of six-layer platinum diselenide (PtSe2) as an interlayer between the thin gold film and SiO2 substrate to induce spontaneous formation of plasmonic nanostructures (nanoribbons) on the upper gold film (∼8 nm) under 1030 nm femtosecond laser irradiation. The formation of periodic nanostructures is attributed to the periodic energy deposition that occurs in the PtSe2 layers under intense femtosecond laser pulses. Notably, the self-assembled gold nanostructures exhibit a distinctive polarization-dependent plasmonic response in the near-infrared spectral region and could be directly fabricated in a centimeter scale within several minutes. This straightforward method for self-assembling plasmonic nanostructures using layered materials may expand the utility of functional 2D materials and advance the cost-effective and large-area fabrication of plasmonic thin-film nanostructures in a simplified manner.

Angular uniformity improvement of diffractive waveguide display based on region geometry optimization.

Augmented reality (AR) near-eye displays have significantly progressed due to advances in nanostructure fabrication. However, for diffractive waveguide AR displays requiring exit pupil expansion, the angular uniformity of each exit pupil position still needs to improve. In this paper, an angular uniformity improvement method based on region geometry optimization is proposed. This optimization method essentially introduces the interaction number of the light with the grating as one of the variables to manipulate the energy distribution. This distribution is obtained by the rigorous coupled wave analysis (RCWA) method and ray tracing process and is further optimized by a multi-objective genetic algorithm. A model is built, and the feasibility of the proposed method is verified. The diffractive waveguide system has a 10m m×10m m exit pupil size at the eye relief of 25mm and a field of view (FOV) of 21∘×12∘. After the optimization, the overall optical efficiency of the central field and the angular uniformity at the center exit pupil position increased from 0.9% and 66% to 3.1% and 80%, respectively.

Synthesis, Fabrication, and Performance Evaluation of Nickel-Cobalt Sulfide Nanostructures for Enhancing Energy Density of Supercapacitors in Energy Storage Applications

Synthesis, Fabrication, and Performance Evaluation of Nickel-Cobalt Sulfide Nanostructures for Enhancing Energy Density of Supercapacitors in Energy Storage Applications

Programming of Supercrystals Using Replicable DNA-Functionalized Colloids.

The development of self-replicating systems is of great importance in research on the origin of life. As the most iconic molecules, nucleic acids have provided prominent examples of the fabrication of self-replicating artificial nanostructures. However, it is still challenging to construct sophisticated synthetic systems that can create large-scale or three-dimensionally ordered nanomaterials using self-replicating nanostructures. By integrating a template system containing DNA-functionalized colloidal seeds with a simplified DNA strand-displacement circuit programmed subsystem to produce DNA-functionalized colloidal copies, we developed a facile enthalpy-mediated strategy to control the replication and catalytic assembly of DNA-functionalized colloids in a time-dependent manner. The replication efficiency and crystal quality of the resulting superlattice structures can be effectively increased by regulating the molar ratio of the template to the copy colloids. By constructing binary systems from two types of gold nanoparticles (or proteins), superlattice structures with different crystal symmetries can be obtained through the replication and catalytic assembly processes. This programmable enthalpy-mediated approach was easily leveraged to achieve the phase transformation and catalytic amplification of colloidal crystals starting from different initial template crystals. This work offers a potential way to construct self-replicating artificial systems that exhibit complicated phase behaviors and can produce large-scale superlattice nanomaterials.

Separation of Halogen Atoms by Sodium from Dehalogenative Reactions on a Au(111) Surface.

On-surface dehalogenative reactions have been promising in the construction of nanostructures with diverse morphologies and intriguing electronic properties, while halogen (X), as the main byproduct, often impedes the formation of extended nanostructures and property characterization, and the reaction usually requires high C-X activation temperatures, especially on relatively inert Au(111). Enormous efforts in precursor design, halogen-to-halide conversion, and the introduction of extrinsic metal atoms have been devoted to either eliminating dissociated halogens or reducing reaction barriers. However, it is still challenging to separate halogens from molecular systems while facilitating C-X activation under mild conditions. Herein, a versatile halogen separation strategy has been developed based on the introduction of extrinsic sodium (Na) into dehalogenative reactions on Au(111) as model systems that both isolates the dissociated halogens and facilitates the C-Br activation under mild conditions. Moreover, the combination of scanning tunneling microscopy imaging and density functional theory calculations reveals the formation of sodium halides (NaX) from halogens in these separation processes as well as the reduction in reaction temperatures and barriers, demonstrating the versatility of extrinsic sodium as an effective "cleaner" and "dehalogenator" of surface halogens. Our study demonstrates a valuable strategy to facilitate the on-surface dehalogenative reactions, which will assist in the precise fabrication of low-dimensional carbon nanostructures.

Anodizing Tungsten Foil with Ionic Liquids for Enhanced Photoelectrochemical Applications.

This research examines the influence of adding a commercial ionic liquid to the electrolyte during the electrochemical anodization of tungsten for the fabrication of WO3 nanostructures for photoelectrochemical applications. An aqueous electrolyte composed of 1.5 M methanesulfonic acid and 5% v/v [BMIM][BF4] or [EMIM][BF4] was used. A nanostructure synthesized in an ionic-liquid-free electrolyte was taken as a reference. Morphological and structural studies of the nanostructures were performed via field emission scanning electron microscopy and X-ray diffraction analyses. Electrochemical characterization was carried out using electrochemical impedance spectroscopy and a Mott-Schottky analysis. From the results, it is highlighted that, by adding either of the two ionic liquids to the electrolyte, well-defined WO3 nanoplates with improved morphological, structural, and electrochemical properties are obtained compared to samples synthesized without ionic liquid. In order to evaluate their photoelectrocatalytic performance, the samples were used as photocatalysts to generate hydrogen by splitting water molecules and in the photoelectrochemical degradation of methyl red dye. In both applications, the nanostructures synthesized with the addition of either of the ionic liquids showed a better performance. These findings confirm the suitability of ionic liquids, such as [BMIM][BF4] and [EMIM][BF4], for the synthesis of highly efficient photoelectrocatalysts via electrochemical anodization.

On-surface photo-induced dechlorination

On-surface Ullmann-type reaction, or the dehalogenated coupling, is arguably the most pivotal reaction in on-surface synthesis for the fabrications of carbon nanostructures. Hitherto, the vast majority of works rely on activating the C-Br bond of aryl bromide which has a moderate bond dissociation energy. The C-Cl bond of aryl chloride has a higher dissociation energy and requires much higher thermal energy to break the bond. In this study, we have explored the on-surface photo-induced dechlorination and achieved the activation of three distinct aryl chlorines on the Au(111) surface with mild temperatures. This work enriches our understanding of on-surface photo-induced reactions and highlights the potential of photochemistry in realizing unconventional reactions.

One-step synthesis and fabrication of ZrMo2O8 nanostructures as advanced electrode material for energy storage applications

Nanostructures of metal molybdates show great potential as high-performance electrode materials for the forthcoming development of energy storage devices. In present work, ZrMo2O8 nanostructure was constructed using a simple chemical procedure and followed by examination with the aid of several spectral and analytical tools. The supercapacitive properties of ZrMo2O8 electrode material were investigated using Cyclic voltammetry (CV), Galvanostatic charge–discharge (GCD) and Electrochemical Impedance Spectroscopy measurements (EIS). The as-prepared ZrMo2O8 nanostructures as supercapacitor (SC) electrode material exhibited pseudocapacitive performance with notable value of 288C g−1 at 1 A/g, significant cycling stability and 92.5% capacity retention with the coulombic efficiency of 87.4% even after 5000 GCD cycles at 1 A/g. The morphological investigations indicated that the higher Specific capacity (Cs) was primarily caused by the significant increase in active sites as well as active surface area. The Bode phase angle plot of ZrMo2O8 exhibited a low frequency intercept, with emphasis at approximately −52° phase angle, indicating a superior redox signature. The results infered that ZrMo2O8 nanostructures are promising candidates for high performance energy storage applications.