Nanocone Structures Research Articles

Rational Fabrication of Superhydrophobic Nanocone Surface for Dynamic Water Repellency and Anti-icing Potential

In this work, a simple and economic route was presented to fabricate an anti-icing superhydrophobic surface with nanocone structures, which were constructed only by one-step facile method of hydrothermal treatment with zinc acetate on the aluminum substrate. After modifying with fluoroalkylsilane (FAS-17), the nanocone structures with the appropriate size could induce the high superhydrophobicity with the water contact angle reaching 160.2° ± 0.4° and the sliding angle only being 1° ± 0.5°. Under the dynamic environments, the impact droplets could rapidly bounced off the surface with the shorter contact time of ~10.6 ms, and it was mainly attributing to lower capillary adhesive force (water adhesion force of 4.1 μN) induced by the open system of nanocone structures. Furthermore, the superhydrophobic nanocone surfaces were verified to be a promising anti-icing/icephobic materials, on which the water droplets needed to spend the time of ~517 s to complete the entire freezing process at −10 °C, displaying the increased ~50 times of icing-delay performance comparing with untreated substrate. Even if ice finally was formed on the superhydrophobic nanocone surfaces, it could be easily removed away with lower ice adhesion of ~45 kPa. The repeatable measurement of ice adhesion strength on the same place of the superhydrophobic surface is still far less than the surface ice adhesion of smooth substrate, exhibiting better stability.

Hierarchical growth of a novel Mn-Bi coupled BiVO4 arrays for enhanced photoelectrochemical water splitting

Oxygen evolving catalyst (OEC) is a critical determinant for the efficiency of photoelectrochemical (PEC) water splitting. Here we report an approach to depositing a novel manganese borate (Mn-Bi) OER catalyst on BiVO4 nanocone photoanode by photodeposition in sodium borate buffer solution containing Mn(II) ions. Due to the spontaneous photo-electric-field-enhancement effect at the vertically oriented BiVO4 nanocone structure, spherical Mn-Bi nanoparticle was selectively photodeposited at the apex of BiVO4 nanocone. Significant improvement of photocurrent was observed for the obtained hierarchical Mn-Bi/BiVO4 photoanode which could be ascribed to enhanced hole injection efficiency, especially in low bias region. It was observed that the injection efficiency of Mn-Bi/BiVO4 is 98% which gave a photocurrent of 0.94 mA/cm2 at 1.5 V vs. RHE.

Morphological variation of electrodeposited nanostructured Ni-Co alloy electrodes and their property for hydrogen evolution reaction

Nanostructured nickel-cobalt alloys of the content of Co varying from 0% to 75% for hydrogen evolution reaction were fabricated by galvanostatic electrochemical deposition processes. With the incorporation of Co into Ni matrix, the morphologies of Ni-Co alloys are changed from nanocones to lamellar structure and finally evolved to a mixed shape of nanocone structure and lamellar structure. Among these Ni-Co alloys, the optimal Ni-60%Co alloy exhibits outstanding electrocatalytic activity with a small hydrogen overpotential of −180 mV and follows Volmer-Tafel mechanism. Better performance of Ni-60%Co can be attributed to the synergetic combination of Ni and Co and unique complex mesh structure which provides the enlarged exposure of catalytically active sites. In addition, Ni-60%Co alloy also displays good electrochemical stability under 10 h galvanostatic test. With prominent electrochemical properties, Ni-60%Co alloy has a certain advantage in the catalytic hydrogen evolution material.

Injection-Molded Microfluidic Device for SERS Sensing Using Embedded Au-Capped Polymer Nanocones.

To enable affordable detection and diagnostic, there is a need for low-cost and mass producible miniaturized sensing platforms. We present a fully polymeric microfluidic lab-on-a-chip device with integrated gold (Au)-capped nanocones for sensing applications based on surface-enhanced Raman spectroscopy (SERS). All base components of the device were fabricated via injection molding (IM) and can be easily integrated using ultrasonic welding. The SERS sensor array, embedded in the bottom of a fluidic channel, was created by evaporating Au onto IM nanocone structures, resulting in densely packed Au-capped SERS active nanostructures. Using a Raman active model analyte, trans-1,2-bis-(4-pyridyl)-ethylene, we found a surface-averaged SERS enhancement factor of ∼5 × 106 with a relative standard deviation of 14% over the sensor area (2 × 2 mm2), and a 18% signal variation among substrates. This reproducible fabrication method is cost-effective, less time consuming, and allows mass production of fully integrated polymeric, microfluidic systems with embedded high-density and high-aspect ratio SERS sensor.

Doped aluminum nanocones as an efficient electron field emitter: A first-principles investigation

We report on the basis of density functional theory, the field emission properties of pristine and doped aluminum nanocone (Al-NC). We substituted the apex of the Al-NC with group IV and group V elements, namely arsenic (As), germanium (Ge) and phosphorous (P) atoms and had carried out studies on these nanocone structures. The density of states (DOS) spectrum gives a clear perception of the charge distribution over the Al-NC surface on doping. Furthermore, the Richardson-Dushman formula has been used to correlate the work function Φ and the charge density. We have observed that doping at the apex of Al-NC leads to the variation in work function Φ. The results show that the field emission properties of Al-NC can be improved with the substitution of As, Ge, and P at the apex of the structure. Our findings suggest that doping of the Al-NC with Ge, As and P leads to the improved field emission properties, which can be used for nanoelectronics and vacuum electronics.

GaP nanocones covered with silver nanoparticles for surface-enhanced Raman spectroscopy

This work describes the preparation of surface-enhanced Raman spectroscopy (SERS) substrates based on GaP nanocones decorated with Ag nanoparticles. The GaP nanocones were grown by metal organic vapour phase epitaxy and then covered with silver nanoparticles produced by a simple electroless method from a silver nitrate solution. The Ag nanoparticle/GaP nanocone structure acted as an effective SERS substrate as it exhibited a significantly higher Raman signal sensitivity compared with that of a planar GaP substrate covered with Ag nanoparticles. The three-dimensional Ag nanoparticle/GaP nanocone substrate was shown to be appropriate for SERS applications, which was demonstrated by the detection of Rhodamine 6G delivered onto the substrate from an aqueous Rhodamine 6G solution at a concentration of 10−2 M.

Subjective somatic symptoms among victims of offensive behaviors at the workplace

Nanostructured nickel-cobalt alloys of the content of Co varying from 0% to 75% for hydrogen evolution reaction were fabricated by galvanostatic electrochemical deposition processes. With the incorporation of Co into Ni matrix, the morphologies of Ni-Co alloys are changed from nanocones to lamellar structure and finally evolved to a mixed shape of nanocone structure and lamellar structure. Among these Ni-Co alloys, the optimal Ni-60%Co alloy exhibits outstanding electrocatalytic activity with a small hydrogen overpotential of −180 mV and follows Volmer-Tafel mechanism. Better performance of Ni-60%Co can be attributed to the synergetic combination of Ni and Co and unique complex mesh structure which provides the enlarged exposure of catalytically active sites. In addition, Ni-60%Co alloy also displays good electrochemical stability under 10 h galvanostatic test. With prominent electrochemical properties, Ni-60%Co alloy has a certain advantage in the catalytic hydrogen evolution material.

Large-scale broadband absorber based on metallic tungsten nanocone structure

We report a broadband tungsten absorber based on a nanocone metallic resonant structure fabricated by self-assembly nanosphere lithography. In experimental demonstration, the fabricated absorber has more than 90% average absorption efficiency and shows superior angular tolerance in the entire visible and near-infrared spectral region. We envision that this large-scale nanostructured broadband optical absorber would find great potential in the applications of high performance optoelectronic platforms and solar-thermal energy harvesting systems.

Inclusion complexes between cisplatin and oxidized carbon nanostructures: A theoretical approach

The toxicity of inclusion compounds formed by carbon nanostructures depends on its functionalized surface, use of solvents, dosage and other properties. Molecular modeling has potentially contributed to the understanding of the chemical nature of the formation of these systems and allows advancement in studies of the mechanism of transport, release of drugs and their biological implications. This work reports a quantum chemical investigation of the inclusion complexes formation between oxidized carbon nanotube (CNTox)/nanocone (CNCox) structure and cisplatin molecule, using the density functional theory (DFT) with the B3LYP functional and 6–31G(d,p)/LanL2DZ standard basis sets. Our results indicate that the cDDP@CNTox (inclusion complex – cisplatin into oxidized carbon nanotube) and cDDP@CNCox (inclusion complex – cisplatin into oxidized carbon nanocone) systems form stable molecular complexes that can be used as drug delivery devices. Our theoretical simulation of molecular spectra (IR, Raman and 1H NMR) reveals substantial changes due to complex formation that can be easily experimentally observed.

Polarization dependent nanostructuring of silicon with femtosecond vortex pulse

We fabricated conical nanostructures on silicon with a tip dimension of ∼ 70 nm using a single twisted femtosecond light pulse carrying orbital angular momentum (ℓ=±1). The height of the nano-cone, encircled by a smooth rim, increased from ∼ 350 nm to ∼ 1 μm with the pulse energy and number of pulses, whereas the apex angle remained constant. The nano-cone height was independent of the helicity of the twisted light; however, it is reduced for linear polarization compared to circular at higher pulse energies. Fluid dynamics simulations show nano-cones formation when compressive forces arising from the radial inward motion of the molten material push it perpendicular to the surface and undergo re-solidification. Simultaneously, the radial outward motion of the molten material re-solidifies after reaching the cold boundary to form a rim. Overlapping of two irradiated spots conforms to the fluid dynamics model.

Surface nanostructuring of CuIn1−xGaxSe2 films using argon plasma treatment

In this work we report a phenomenon of the self-formation of nanostructure arrays during low-energy inductively coupled argon plasma treatment of the surface of copper indium gallium diselenide films grown by different methods on glass substrates. Selenization, pulsed laser deposition and multistage co-evaporation technological methods were used for the growth of polycrystalline CuIn1−xGaxSe2 (0.04 ≤ x ≤ 0.45) films. The plasma treatment of the surface of the films grown by all three methods resulted in the plasma-assisted self-formation of arrays of uniform cylindrical or conical nanostructures with the surface density of (0.8–1.8) × 1011 cm−2. Using scanning electron microscopy, transmission electron microscopy and atomic force microscopy, we describe the morphological parameters and chemical composition of the fabricated nanostructures and discuss possible physical mechanisms of the observed plasma-assisted nanostructuring.

Novel fabrication method for integration of template grown metallic nanocones with controllable tip diameter and apex angle

Conical metallic nanostructures, due to their geometrical and physical properties, are advantageous compared to cylindrical nanowires in applications like electron field emission cathodes. In this paper a new method for fabrication and integration of vertically aligned metallic nanocones with random distribution is reported. The nanocones are deposited electrochemically at temperatures about 60°C and lower. An area of ca. 1cm2 is covered with nanocones. The density of nanocones ranges between 6×104 and 2×106cm−2, which gives a pitch range of 23 to 7μm. With this process the growth and integration of nanocones made of different materials like e.g. Au, Ni and Cu are enabled. The tip diameter of the cones can be modified between 50 and 700nm and the base diameter between 2.5 and 7μm, i.e. apex angles between 5.9° and 16.6° can be obtained. The surface roughness of the nanocone arrays is ±0.2μm.

Significant light absorption improvement in perovskite/CIGS tandem solar cells with dielectric nanocone structures

Here, we propose a novel perovskite/CIGS tandem solar cell geometry with tailored dielectric nanocone structure incorporated on the top surface for light manipulation. Absorption enhancement as high as 15.39% has been achieved both in the top and bottom subcells, leading to a 14.29% thickness reduction of the bottom subcell.

Optical control of spectral diffusion with single InAs quantum dots in a silver-embedded nanocone

We study the spectral diffusion in a single epitaxial InAs quantum dot placed in a silver-embedded nanocone structure. Making use of a series of stroboscopic detection of optical transitions, we demonstrate the temporal fluctuations in peak energy of photoluminescence. In particular, the photoluminescence fluctuations can be effectively suppressed by strong illumination. By analyzing the photon statistics, we find that the dot emission exhibits stable non-classical nature with the strong anti-bunching behavior after this stabilization.

Effect of Crystal Orientation on Self-Assembly Nanocones Formed on Tungsten Surface Induced by Helium Ion Irradiation and Annealing.

The self-assembly nanocone structures on the surface of polycrystalline tungsten were created by He+ ion irradiation and then annealing, and the resulting topography and morphology were characterized using atomic force microscopy and scanning electron microscopy. The cross-sectional samples of the self-assembly nanocones were prepared using an in situ–focused ion beam and then observed using transmission electron microscopy. The self-assembly nanocones were induced by the combined effect of He+ ion irradiation, the annealing process and the chromium impurity. The distribution characteristics, density and morphology of the nanocones exhibited a distinct difference relating to the crystal orientations. The highest density of the nanocones was observed on the grain surface with a (1 1 1) orientation, with the opposite for that with a (0 0 1) orientation and a medium value on the (1 0 1)-oriented grain. The size of the self-assembly nanocones increased with increasing the annealing time which met a power-law relationship. Irradiation-induced defects acted as the nucleation locations of the protrusions which attracted the migration of the tiny amount of chromium atoms. Under the action of temperature, the protrusions finally evolved into the nanocones.

Polarization Control via He-ion Beam Induced Nanofabrication in Layered Ferroelectric Semiconductors

Rapid advances in nanoscience rely on continuous improvements of material manipulation at near-atomic scales. Currently, the workhorse of nanofabrication is resist-based lithography and its various derivatives. However, the use of local electron, ion, and physical probe methods is expanding, driven largely by the need for fabrication without the multistep preparation processes that can result in contamination from resists and solvents. Furthermore, probe-based methods extend beyond nanofabrication to nanomanipulation and to imaging which are all vital for a rapid transition to the prototyping and testing of devices. In this work we study helium ion interactions with the surface of bulk copper indium thiophosphate CuM(III)P2X6 (M = Cr, In; X= S, Se), a novel layered 2D material, with a Helium Ion Microscope (HIM). Using this technique, we are able to control ferrielectric domains and grow conical nanostructures with enhanced conductivity whose material volumes scale with the beam dosage. Compared to the copper indium thiophosphate (CITP) from which they grow, the nanostructures are oxygen rich, sulfur poor, and with virtually unchanged copper concentration as confirmed by energy-dispersive X-ray spectroscopy (EDX). Scanning electron microscopy (SEM) imaging contrast as well as scanning microwave microscopy (SMM) measurements suggest enhanced conductivity in the formed particles, whereas atomic force microscopy (AFM) measurements indicate that the produced structures have lower dissipation and are softer as compared to the CITP.

Pt Nanoparticle Sintering and Redispersion on a Heterogeneous Nanostructured Support

Understanding how nanostructure and atomic-scale defects of the support affect metal catalyst nanoparticle sintering is of crucial importance to minimize thermal deactivation, as well as to understand the origin of widely observed but still unexplained phenomena, such as transient multimodal particle size distributions and nanoparticle redispersion. To shed light on these issues, we present a generic experimental approach that relies on nanofabrication to introduce controlled structural heterogeneity in a chemically homogeneous model catalyst support. This is achieved by fabricating arrays of nanocone structures separated by flat areas, where both are homogeneously sputter-coated with a thin amorphous alumina layer. Using ex situ aberration-corrected scanning transmission electron microscopy (STEM) to analyze Pt model catalyst nanoparticles on such nanostructured supports prior and after exposure to 4% O2 in Ar carrier gas at 600 °C, we find that the initial particle size distributions and their time evol...

Structure, Properties, Functionalization, and Applications of Carbon Nanohorns.

Carbon nanohorns (sometimes also known as nanocones) are conical carbon nanostructures constructed from an sp(2) carbon sheet. Nanohorns require no metal catalyst in their synthesis, and can be produced in industrial quantities. They provide a realistic and useful alternative to carbon nanotubes, and possibly graphene, in a wide range of applications. They also have their own unique behavior due to their specific conical morphology. However, their research and development has been slowed by several factors, notably during synthesis, they aggregate into spherical clusters ∼100 nm in diameter, blocking functionalization and treatment of individual nanocones. This limitation has recently been overcome with a new approach to separating these "dahlia-like" clusters into individual nanocones. In this review, we describe the structure, synthesis, and topology of carbon nanohorns, and provide a detailed review of nanohorn chemistry.

Polarization Control via He-Ion Beam Induced Nanofabrication in Layered Ferroelectric Semiconductors.

Rapid advances in nanoscience rely on continuous improvements of material manipulation at near-atomic scales. Currently, the workhorse of nanofabrication is resist-based lithography and its various derivatives. However, the use of local electron, ion, and physical probe methods is expanding, driven largely by the need for fabrication without the multistep preparation processes that can result in contamination from resists and solvents. Furthermore, probe-based methods extend beyond nanofabrication to nanomanipulation and to imaging which are all vital for a rapid transition to the prototyping and testing of devices. In this work we study helium ion interactions with the surface of bulk copper indium thiophosphate CuM(III)P2X6 (M = Cr, In; X= S, Se), a novel layered 2D material, with a Helium Ion Microscope (HIM). Using this technique, we are able to control ferrielectric domains and grow conical nanostructures with enhanced conductivity whose material volumes scale with the beam dosage. Compared to the copper indium thiophosphate (CITP) from which they grow, the nanostructures are oxygen rich, sulfur poor, and with virtually unchanged copper concentration as confirmed by energy-dispersive X-ray spectroscopy (EDX). Scanning electron microscopy (SEM) imaging contrast as well as scanning microwave microscopy (SMM) measurements suggest enhanced conductivity in the formed particles, whereas atomic force microscopy (AFM) measurements indicate that the produced structures have lower dissipation and are softer as compared to the CITP.

Fabrication of nanocone arrays by two step metal assisted chemical etching method

This work develops a novel method for preparing a moth eye structure, which has a sub-wavelength periodical Si nanocone structure on Si(100) substrate, using two-step metal assisted chemical etching (MACE). The 1st MACE and 2nd MACE were respectively performed with the intention to form perpendicular Si nanowire arrays on a Si substrate and sharpening the Si nanowire arrays. We found that the inhomogeneous absorption and aggregation of Au particles used as a catalyst for the 2nd MACE was important to obtain the nanocone shape. The obtained Si nanocone arrays showed superior anti-reflecting properties especially in a wavelength below 600nm compared with the Si nanowire arrays. A possible mechanism involved in the formation of the nanocone structure by the 2-step MACE is discussed in this paper.