Incorporation Of Nanostructures Research Articles

Nanostructured Pd/Ag/Ni electrocatalysts for the Hydrogen Evolution Reaction

As palladium is the one of the most effective electrocatalyst for the hydrogen evolution reaction, it is crucial the development of new catalysts that require small amounts of palladium to perform, but that are highly active. In this work, the electrochemical characterization of a novel electrode with low palladium content is reported, where Pd nanoparticles are supported on macroporous nickel electrodes that contain silver nanoparticles previously electrodeposited on the surface, which after heat-treatment become rich in corners and edges. The values of η100 (overpotential needed to produce a fixed amount of hydrogen) and jm (indicative of catalytic activity per unit mass of metal nanoparticles) improved (for example, at 80 °C, a η100 of 109.9 mV and a jm of 12587 A·g−1) those of other authors who applied bimetallic AgPd nanoparticles for the HER, showing that the incorporation of nanostructures (Pd over Ag) significantly reduced the energy investment required to produce hydrogen due to synergistic effects between the deposited Pd particles and the electrodeposited silver, enhancing the catalytic activity.

Synthesis of nanocomposites based on Fe3O4 nanoparticles and nitrogen-doped reduced graphene oxide aerogel by ex-situ approach and their magnetic properties

In this study, were synthesised hybrid nanocomposites (Fe3O4@NrGO) using magnetite nanoparticles (Fe3O4-NPs) and nitrogen-doped reduced graphene oxide (NrGO) aerogel through ex-situ approach, which is simple and easily scalable. The NrGO exhibited 7.96 at% N, demonstrated efficient doping and a high content of active nitrogen sites within the composite matrix. Structural, morphological, and elemental analyses of the obtained nanocomposites confirmed the successful incorporation of Fe3O4-NPs into both doped and undoped aerogel matrices (rGO). The presence of nitrogen sites greatly influenced the interaction and incorporation of nanostructures, as evident from the well-distributed and denser nanoparticle arrangement in Fe3O4@NrGO. The impact of matrix doping was also highlighted through porosity analyses, revealing increases in both; pore volume and surface area. Porosity analysis emphasised the efficacy of the ex-situ strategy and the use of aerogel as the matrix, enabling the achievement of a surface area of 1456 m2 g−1 for Fe3O4@NrGO, owing to the particular swelling mechanism of the “spongy” structure. Vibrating-sample magnetometry and electron paramagnetic resonance spectroscopy techniques were employed to investigate the influence of nitrogenous sites on magnetic properties. The higher nanoparticle density in Fe3O4@NrGO resulted in a saturation magnetisation of 0.7219 emu g−1, more than double that of Fe3O4 @rGO. Resonant peaks at low magnetic fields, characterised by a g-factor of 4.4219, were attributed to paramagnetic nitrogen centres that facilitated the efficient anchoring of Fe3O4-NPs in NrGO

Photochemical outcomes triggered by gold shell-isolated nanorods on bioinspired nanoarchitectonics for bacterial membranes

Boosted by the indiscriminate use of antibiotics, multidrug-resistance (MDR) demands new strategies to combat bacterial infections, such as photothermal therapy (PTT) based on plasmonic nanostructures. PTT efficiency relies on photoinduced damage caused to the bacterial machinery, for which nanostructure incorporation into the cell envelope is key. Herein, we shall unveil the binding and photochemical mechanisms of gold shell-isolated nanorods (AuSHINRs) on bioinspired bacterial membranes assembled as Langmuir and Langmuir-Schaefer (LS) monolayers of DOPE, Lysyl-PG, DOPG and CL. AuSHINRs incorporation expanded the isotherms, with stronger effect on the anionic DOPG and CL. Indeed, FTIR of LS films revealed more modifications for DOPG and CL owing to stronger attractive electrostatic interactions between anionic phosphates and the positively charged AuSHINRs, while electrostatic repulsions with the cationic ethanolamine (DOPE) and lysyl (Lysyl-PG) polar groups might have weakened their interactions with AuSHINRs. No statistical difference was observed in the surface area of irradiated DOPE and Lysyl-PG monolayers on AuSHINRs, which is evidence of the restricted nanostructures insertion. In contrast, irradiated DOPG monolayer on AuSHINRs decreased 4.0 % in surface area, while irradiated CL monolayer increased 3.7 %. Such results agree with oxidative reactions prompted by ROS generated by AuSHINRs photoactivation. The deepest AuSHINRs insertion into DOPG may have favored chain cleavage while hydroperoxidation is the mostly like outcome in CL, where AuSHINRs are surrounding the polar groups. Furthermore, preliminary experiments on Escherichia coli culture demonstrated that the electrostatic interactions with AuSHINRs do not inhibit bacterial growth, but the photoinduced effects are highly toxic, resulting in microbial inactivation.

A proposal to enhance SnS solar cell efficiency: the incorporation of SnSSe nanostructures

Tin sulfide (SnS) semiconductor has recently attracted a great deal of attention from the scientific community regarding its application in solar cells. However, SnS solar cell efficiencies are still limited to less than 5%. The incorporation of nanostructures into solar cells has been demonstrated to be a potential route to improve device performance. So far, there have been no reports on the incorporation of nanostructures into SnS solar cells. In this work, a theoretical study on the incorporation of tin sulfide selenide (SnSSe) nanostructures in the form of quantum wells (QWs) into SnS solar cells under the radiative limit is presented, for the first time. In particular, the impact of well number, well thickness, and Se/(S + Se) compositional ratio at the wells, on solar cell characteristics, is evaluated. An efficiency enhancement of 11.1% is found for a SnS/SnSSe QW solar cell, compared to the optimized device without nanostructures, for 50 wells of 54 nm width with a Se/(S + Se) well composition of 0.4 and considering barrier thicknesses of 5 nm, which is a result of the increase in short-circuit current density of 14.5%. The influence of defects at wells and barriers, as well as defects at interfaces, on solar cell behavior is also presented, demonstrating that the introduction of QWs can result in higher efficiencies than that of the device without nanostructures. In this sense, the addition of SnSSe nanostructures to SnS solar cells is introduced as a potential route to promote the absorption of photons with energy lower than the SnS band-gap, while keeping open-circuit voltage values similar to those of a SnS solar cell without nanostructures, thereby increasing solar cell efficiency.

Solution processing of chalcogenide glasses: A facile path towards functional integration

Chalcogenide Glasses (ChGs) are technologically promising materials widely used in different optical, electronic and optoelectronic applications. Solution processing of ChGs has provided a pathway for less complex thin film processing of these materials and their integration into flexible devices. This paper reviews the basic science behind the solution processing of ChGs, properties of solution processed ChG films and recent functional applications of solution processed ChGs. Solution processing of ChGs also provides the facile method of incorporation of nanostructures into ChG matrix which integrate the functional properties of nanostructures and ChGs in a single solution or thin film. This paper also reviews the research work undertaken on the incorporation of nanostructures in ChGs. • This paper presents a review of synthesis, properties and applications of Chalcogenide glass (ChG) films obtained by solution processing. • It discusses the chemistry involved in the processing of glasses, which helps in understanding the control over stoichiometry of ChG. • This review also provides insights on some recent application of solution processed chalcogenide glasses. • A review on the research work done on the incorporation of nanostructures in ChGs is also presented.

A reproducible, low cost microfluidic microcavity array SERS platform prepared by soft lithography from a 2 photon 3D printed template

As they are widely implemented as features formed at a continuous metal surface, Surface-enhanced Raman spectroscopy (SERS) substrates are amenable to implementation in a microfluidic format. However, achieving reproducibility and repeatability in platform fabrication often requires methods that are complex and expensive, restricting transfer from laboratory prototyping to mass production. Herein, a new and robust, low cost technique for cavity array SERS substrate fabrication and its integration into a microfluidic device is described. The fabrication relies on 2-photon 3D printing of a master template and enables batch fabrication of reproducible arrays with sub-micron resolution and uncomplicated modification of the cavity architecture. With this approach, significant Raman signal enhancement of up to 6.7 × 107 through incorporation of nanostructures - plasmonic “hot-spots” and straightforward integration into microfluidic device was achieved. In addition, implementing the nano-sub-structuring to the cavities by 2-photon 3D printing approach, we obtain reproducible enhancements of SERS intensity of more than 4 fold in comparison to arrays fabricated using previously established sphere templating techniques. The fabricated microfluidic device showed detection capability for cholesterol analyte in solution in a simple demonstration where the array was modifed with thiolated cyclodextrin host to enable analyte capture.

Universal Transfer Printing of Micelle-Templated Nanoparticles Using Plasma-Functionalized Graphene.

Nanostructure incorporation into devices plays a key role in improving performance, yet processes for preparing two-dimensional (2D) arrays of colloidal nanoparticles tend not to be universally applicable, particularly for soft and oxygen-sensitive substrates for organic and perovskite-based electronics. Here, we show a method of transferring reverse micelle-deposited (RMD) nanoparticles (perovskite and metal oxide) on top of an organic layer, using a functionalized graphene carrier layer for transfer printing. As the technique can be applied universally to RMD nanoparticles, we used magnetic (γ-Fe2O3) and luminescent (methylammonium lead bromide (MAPbBr3)) nanoparticles to validate the transfer-printing methodology. The strong photoluminescence from the MAPbBr3 under UV illumination and high intrinsic field of the γ-Fe2O3 as measured by magnetic force microscopy (MFM), coupled with Raman measurements of the graphene layer, confirm that all components survive the transfer-printing process with little loss of properties. Such an approach to introducing uniform 2D arrays of nanoparticles onto sensitive substrates opens up new avenues to tune the device interfacial properties.

Encapsulation of Nanostructures in a Dielectric Matrix Providing Optical Enhancement in Ultrathin Solar Cells

The incorporation of nanostructures in optoelectronic devices for enhancing their optical performance is widely studied. However, several problems related to the processing complexity and the low performance of the nanostructures have hindered such actions in real‐life devices. Herein, a novel way of introducing gold nanoparticles in a solar cell structure is proposed in which the nanostructures are encapsulated with a dielectric layer, shielding them from high temperatures and harsh growth processing conditions of the remaining device. Through optical simulations, an enhancement of the effective optical path length of approximately four times the nominal thickness of the absorber layer is verified with the new architecture. Furthermore, the proposed concept in a Cu(In,Ga)Se2 solar cell device is demonstrated, where the short‐circuit current density is increased by 17.4%. The novel structure presented in this work is achieved by combining a bottom‐up chemical approach of depositing the nanostructures with a top‐down photolithographic process, which allows for an electrical contact.

Ultralow thermal conductivity and high thermoelectric figure of merit in Cu2Te–Ag2Te composites

Incorporation of nanostructures into bulk materials is an important strategy to enhance the thermoelectric figure of merit (zT). Herein, nanostructured Ag2Te (prepared by wet chemical synthesis) was mechanically alloyed with bulk Cu2Te (synthesized via melting route) to form composites of (Cu2Te)100-x–(Ag2Te)x (where x varies from 0 to 50). The alloying increased the thermoelectric power factor from ∼0.18 mW m−1K−2 (for pristine Cu2Te) to ∼0.47 mW m−1K−2 for the composite at 588 K. The thermal conductivity reduced from ∼3.5 W m−1 K−1 in pristine Cu2Te to ∼0.26 W m−1 K−1 in the composites and reaches the theoretical minimum of Cu2Te (∼0.18 W m−1 K−1) at high temperatures due to the additional scattering of carriers as well as phonons by the Ag2Te nanostructures. The combined effect of moderate power factor and ultralow thermal conductivity led to the high zT value of ∼0.99 at 588 K in (Cu2Te)50.00–(Ag2Te)50.00 that represents a significant improvement for Cu2Te based alloys.

Advances in Using Nanotechnology Structuring Approaches for Improving Food Packaging.

Recent advances in food packaging materials largely rely on nanotechnology structuring. Owing to several unique properties of nanostructures that are lacking in their bulk forms, the incorporation of nanostructures into packaging materials has greatly improved the performance and enriched the functionalities of these materials. This review focuses on the functions and applications of widely studied nanostructures for developing novel food packaging materials. Nanostructures that offer antimicrobial activity, enhance mechanical and barrier properties, and monitor food product freshness are discussed and compared. Furthermore, the safety and potential toxicity of nanostructures in food products are evaluated by summarizing the migration activity of nanostructures to different food systems and discussing the metabolism of nanostructures at the cellular level and in animal models.

Diatom frustules enhancing the efficiency of gel polymer electrolyte based dye-sensitized solar cells with multilayer photoelectrodes.

The incorporation of nanostructures that improve light scattering and dye adsorption has been suggested for dye-sensitized solar cells (DSSCs), but the manufacture of photonic and nanostructured materials with the desired properties is not an easy task. In nature, however, the process of light-harvesting for photosynthesis has, in some cases, evolved structures with remarkable wavelength-sensitive light-trapping properties. The present work is focused on enhancing the efficiency of quasi solid-state DSSCs by capitalizing on the light trapping properties of diatom frustules since they provide complex 3-dimensional structures for scattering and trapping light. This study reports a promising approach to prepare TiO2 nanocrystal (14 nm) based photo-electrodes by utilizing the waveguiding and photon localization effects of nanostructured diatom frustules for enhancing light harvesting without deteriorating the electron conduction. Single and double-layered photo-electrodes were prepared with different frustule/nanocrystal combinations and conformations on transparent conductive oxide substrates. This study clearly reports impressive efficiency and short circuit current density enhancements of about 35% and 39%, respectively, due to the incorporation of diatom frustules extracted from a ubiquitous species. The SEM images obtained in this work reveal that the produced thin films had a remarkable surface coverage of evenly distributed frustules within the TiO2 nanoparticle layer. To the best of our knowledge, this study reports the first quasi solid-state DSSC based on a photo-electrode with incorporated bio-formed nanostructures.

Photoconductive Terahertz Near-Field Detector with a Hybrid Nanoantenna Array Cavity

Nanoscale structuring of optical materials leads to modification of their properties and can be used for improving efficiencies of photonic devices and for enabling new functionalities. In ultrafast optoelectronic switches for generation and detection of terahertz (THz) radiation, incorporation of nanostructures allows us to overcome inherent limitations of photoconductive materials. We propose and demonstrate a nanostructured photoconductive THz detector for sampling highly localized THz fields, down to the level of λ/150. The nanostructure that consists of an array of optical nanoantennas and a distributed Bragg reflector forms a hybrid cavity, which traps optical gate pulses within the photoconductive layer. The effect of photon trapping is observed as enhanced absorption at a designed wavelength. This optically thin photoconductive THz detector allows us to detect highly confined evanescent THz fields coupled through a deeply subwavelength aperture as small as 2 μm (λ/150 at 1 THz). By monolithically ...

Nanotube Electromechanics beyond Carbon: The Case of WS2

The incorporation of nanostructures into nanoelectronic and nanoelectromechanical systems is a long sought-after goal. In the present article, we report the first torsional electromechanical measurements of pure inorganic nanotubes. The WS2 nanotubes exhibited a complex and reproducible electrical response to mechanical deformation. We combined these measurements with density-functional-tight-binding calculations to understand the interplay between mechanical deformation, specifically torsion and tension, and electrical properties of WS2 nanotubes. This yielded the understanding that the electrical response to mechanical deformation may span several orders of magnitude on one hand and detect several modes of mechanical deformation simultaneously on the other. These results demonstrate that inorganic nanotubes could thus be attractive building blocks for nanoelectromechanical systems such as highly sensitive nanometric motion sensors.

Mesoporous bioactive glass nanolayer-functionalized 3D-printed scaffolds for accelerating osteogenesis and angiogenesis.

The hierarchical microstructure, surface and interface of biomaterials are important factors influencing their bioactivity. Porous bioceramic scaffolds have been widely used for bone tissue engineering by optimizing their chemical composition and large-pore structure. However, the surface and interface of struts in bioceramic scaffolds are often ignored. The aim of this study is to incorporate hierarchical pores and bioactive components into the bioceramic scaffolds by constructing nanopores and bioactive elements on the struts of scaffolds and further improve their bone-forming activity. Mesoporous bioactive glass (MBG) modified β-tricalcium phosphate (MBG-β-TCP) scaffolds with a hierarchical pore structure and a functional strut surface (∼100 nm of MBG nanolayer) were successfully prepared via 3D printing and spin coating. The compressive strength and apatite-mineralization ability of MBG-β-TCP scaffolds were significantly enhanced as compared to β-TCP scaffolds without the MBG nanolayer. The attachment, viability, alkaline phosphatase (ALP) activity, osteogenic gene expression (Runx2, BMP2, OPN and Col I) and protein expression (OPN, Col I, VEGF, HIF-1α) of rabbit bone marrow stromal cells (rBMSCs) as well as the attachment, viability and angiogenic gene expression (VEGF and HIF-1α) of human umbilical vein endothelial cells (HUVECs) in MBG-β-TCP scaffolds were significantly upregulated compared with conventional bioactive glass (BG)-modified β-TCP (BG-β-TCP) and pure β-TCP scaffolds. Furthermore, MBG-β-TCP scaffolds significantly enhanced the formation of new bone in vivo as compared to BG-β-TCP and β-TCP scaffolds. The results suggest that application of the MBG nanolayer to modify 3D-printed bioceramic scaffolds offers a new strategy to construct hierarchically porous scaffolds with significantly improved physicochemical and biological properties, such as mechanical properties, osteogenesis, angiogenesis and protein expression for bone tissue engineering applications, in which the incorporation of nanostructures and bioactive components into the scaffold struts synergistically play a key role in the improved bone formation.

Existence and stability of an intermediate wetting state on circular micropillars

It has been recently reported that, after a liquid drop contacts the bottom of a roughness groove, liquid may not completely fill this roughness groove if the groove is covered with nanostructures. Otherwise, liquid may fill the entire groove. In this work, we explore the reasons behind these phenomena for the case of circular micropillars and derive an angle inequality. We show that if the local contact angles satisfy the angle inequality, a locally stable intermediate wetting state may exist. In this intermediate state, liquid does not completely fill the roughness groove, and air pockets still exist in its bottom corners. When roughness grooves have smooth surfaces, the local contact angles are usually less than 135°, violating the angle inequality. However, the incorporation of nanostructures on the grooves may make local contact angles become above 135°, resulting in the satisfaction of the angle inequality. Therefore, the filling phenomena may be different when the grooves are covered with nanostructures or not. In addition to existing experimental results, the derived angle inequality is also validated by in situ observation of water drops in the pressing tests on circular micropillars with and without the coverage of ZnO wires.

Device architectures in organic photovoltaics

The various device structures used in organic polymer solar cells are reviewed. The operating principles behind these devices are explained in order to provide the reasoning behind the dierent structures. The incorporation of nanostructures into both bilayer and bulk heterojunction devices to improve exciton separation, charge transport, and light absorption is discussed. Novel ideas such as electrospun bers and supramolecules are also covered. Finally, the impact of these structures on overall eciency is evaluated.

Recent developments and future possibilities for polymer monoliths in separation science

Within recent years there has been an increase in research focused on the design and application of organic polymer monoliths in all areas of separation science. This is largely driven by the theoretical and practical benefits that these materials should be able to provide, particularly in terms of improved biocompatibility and high permeability. This review summarises recent new developments in this field with a focus on new approaches to the design and synthesis of polymeric monolithic materials for analytical separation science. This includes the use of alternative synthetic methodologies such as the development of hyper-crosslinked monoliths, preparation of hybrid materials and incorporation of nanostructures in the polymeric scaffold. New and developing approaches for the structural characterisation of monolithic columns are also included. Finally, we critically discuss the current chromatographic performances achieved with this column technology as well as where future developments in this field may be directed.

Formation of Crystalline Sodium Hydride Nanoparticles Encapsulated Within an Amorphous Framework

A major research theme to emerge in the science and technology of materials is the incorporation of nanostructure into the functionality of properties. Such nanostructured materials can offer distinct advantages over bulk materials, partly because the physical properties of the material itself can vary in a tunable, size-dependent fashion. Of course, in addition, nanoparticles offer a greatly increased surface area for chemical reaction. Typical methods for nanoparticle synthesis include: reaction in the liquid phase using the sol–gel approach and mechanical ball-milling of the bulk material; both of these approaches are somewhat problematic for the preparation of reactive nanostructured materials which are sensitive to air and/or moisture. We report here the formation of crystalline nanoparticles of sodium hydride encapsulated in a host amorphous silica gel matrix. These nanoparticles are formed by in situ hydrogenation of a precursor material—Na loaded silica gel—under mild conditions. The resulting material is considerably less pyrophoric and less air-sensitive than the bulk hydride. We anticipate that this formation method of in situ modification of reactive precursor material may have wide applications.

Nanograss and nanostructure formation on silicon using a modified deep reactive ion etching

Silicon nanograss and nanostructures are realized using a modified deep reactive ion etching technique on both plane and vertical surfaces of a silicon substrate. The etching process is based on a sequential passivation and etching cycle, and it can be adjusted to achieve grassless high aspect ratio features as well as grass-full surfaces. The incorporation of nanostructures onto vertically placed parallel fingers of an interdigital capacitive accelerometer increases the total capacitance from 0.45 to 30 pF. Vertical structures with features below 100 nm have been realized.

Nanoembossed Polymer Substrates for Biomedical Surface Interaction Studies

Biomedical devices are moving towards the incorporation of nanostructures to investigate the interactions of biological species with such topological surfaces found in nature. Good optical transparency and sealing properties, low fabrication cost, fast design realization times, and biocompatibility make polymers excellent candidates for the production of surfaces containing such nanometric structures. In this work, a method for the production of nanostructures in free-standing sheets of different thermoplastic polymers is presented, with a view to using these substrates in biomedical cell-surface applications where optical microscopy techniques are required. The process conditions for the production of these structures in poly(methyl methacrylate), poly(ethylene naphthalate), poly(lactic acid), poly(styrene), and poly(ethyl ether ketone) are given. The fabrication method used is based on a modified nanoimprint lithography (NIL) technique using silicon based moulds, fabricated via reactive ion etching or focused ion beam lithography, to emboss nanostructures into the surface of the biologically compatible thermoplastic polymers. The method presented here is designed to faithfully replicate the nanostructures in the mould while maximising the mould lifetime. Examples of polymer replicas with nanostructures of different topographies are presented in poly(methyl methacrylate), including nanostructures for use in cell-surface interactions and nanostructure-containing microfluidic devices.