Chemical Phase Deposition Research Articles

Effective Unidirectional Wetting of Liquids on Multi-Gradient, Bio-Inspired Surfaces Fabricated by 3D Printing and Surface Modification.

The movement of liquid droplets on the energy gradient surface has attracted extensive attention inspired by biological features in nature, such as the periodic spindle-shaped nodes in spider silks and conical-like barbs of cacti, and the structure-property-function relationship of multifunctional gradient surfaces. In this study, a series of specific patterns are fabricated with 3D printing technology, followed by modification via the atmospheric pressure plasma treatment and liquid phase chemical deposition, resulting in enhancing the ability of water droplets of 5 μL to travel 18.47 mm on a horizontal plane and 22.75 mm against gravity at up to a 20° tilting angle. Additionally, analysis techniques have been employed, including a contact angle analyzer, ESCA, and a laser confocal microscope to evaluate the sample performance. This work could further be applied to many applications related to microfluidic devices, drug delivery and water/fog collection.

Hexagonal boron nitride nanosheets: Fabrication, thermal properties and application in polymers

Traditional thermally conductive materials are gradually losing their advantages as the electronics industry develops rapidly. Polymers are in urgent need of a material with high thermal conductivity, stable structure, good mechanical properties and oxidation resistance, which makes hexagonal boron nitride (h-BN) an excellent heat transfer filler for polymer composites. Boron nitride nanosheets (BNNS) are monolayers of hexagonal boron nitride, and theoretical studies have shown that BNNS have a higher thermal conductivity than h-BN (up to 400 Wm−1K−1, in-plane). This paper provides a comprehensive review of various methods for preparing BNNS, including mechanical exfoliation, liquid phase sonication exfoliation and chemical vapor deposition (CVD). In addition, various factors affecting the thermal conductivity of BNNS, including grain boundary, grain size and defects, are also discussed. Then, the influence of BNNS as filler on the thermal conductivity of the polymer was further discussed. Finally, this paper summarizes the existing BNNS applications and lists the application scenarios of BNNS in various fields. The purpose of this review is to summarize the previous work and put forward the prospect and future development direction of preparing high thermal conductivity BNNS-included polymer composites, so as to stimulate the research and improvement of new preparation methods for BNNS and promote its practical application as heat transfer materials.

Determination and investigation of defect domains in multi-shape monolayer tungsten disulfide.

Single-layer tungsten disulfide (WS2) is among the most widely investigated two-dimensional materials. Synthesizing it over large areas would enable the exploitation of its appealing optical and electronic properties in industrial applications. However, defects of different nature, concentration and distribution profoundly affect the optical as well as the electronic properties of this crystal. Controlling the defect density distribution can be an effective way to tailor the local dielectric environment and therefore the electronic properties of the system. In this work we investigate the defects in single-layer WS2, grown in different shapes by liquid phase chemical vapor deposition, where the concentration of certain defect species can be controlled by the growth conditions. The properties of the material are surveyed by means of optical spectroscopy, photoelectron spectroscopy and Kelvin probe force microscopy. We determine the chemical nature of the defects and study their influence on the optical and electronic properties of WS2. This work contributes to the understanding of the microscopic nature of the intrinsic defects in WS2, helping the development of defect-based technologies which rely on the control and engineering of defects in dielectric 2D crystals.

Structure-dependent spin-polarized electron transport in twin-crystal Cu1-xEuxO semiconductors.

In this work, Eu-doped twin copper oxide (twin Cu1-xEuxO) was synthesized using the gas-liquid phase chemical deposition method in combination with high-temperature oxidation. The incorporation of Eu3+ ions was affected by their diffusivity and the related charge trapping mechanisms. The twin Cu1-xEuxO configuration exhibited significant room-temperature ferromagnetism. From our analysis, it was demonstrated that as the Eu3+ doping concentration increased, the saturation magnetization first increased and then gradually decreased, reaching a peak at 0.82 at%. A p-type to an n-type semiconducting transition was also recorded as the doping concentration increased. A significant anomalous Hall effect characterized by a maximum anomalous Hall coefficient of 1.65, and a maximum Hall conductivity mobility of 16.50 Ohm-1 cm-1 and 250.59 cm2 v-1 s-1, respectively, were derived for the twin Cu1-xEuxO, doped with 0.82 at% at room temperature. First-principles computational simulations were also conducted to elucidate the underlying mechanisms of the magnetic properties, the p-type to n-type transition, and the interplay between the spin-polarized states associated with 4f and carriers. In twin Cu1-xEuxO, the anomalous Hall effect originated from the contribution of the edge-to-jump scattering mechanism. The latter can be significantly enhanced by doping with Eu atoms, which yields the manifestation of the oblique scattering mechanism. Our work paves the way for the development of twin Cu1-xEuxO material structures, which emerge as an ideal candidate for future spintronic applications.

Graphene Synthesis Techniques and Environmental Applications.

Graphene is fundamentally a two-dimensional material with extraordinary optical, thermal, mechanical, and electrical characteristics. It has a versatile surface chemistry and large surface area. It is a carbon nanomaterial, which comprises sp2 hybridized carbon atoms placed in a hexagonal lattice with one-atom thickness, giving it a two-dimensional structure. A large number of synthesis techniques including epitaxial growth, liquid phase exfoliation, electrochemical exfoliation, mechanical exfoliation, and chemical vapor deposition are used for the synthesis of graphene. Graphene prepared using different techniques can have a number of benefits and deficiencies depending on its application. This study provides a summary of graphene preparation techniques and critically assesses the use of graphene, its derivates, and composites in environmental applications. These applications include the use of graphene as membrane material for the detoxication and purification of water, active material for gas sensing, heavy metal ions detection, and CO2 conversion. Furthermore, a trend analysis of both synthesis techniques and environmental applications of graphene has been performed by extracting and analyzing Scopus data from the past ten years. Finally, conclusions and outlook are provided to address the residual challenges related to the synthesis of the material and its use for environmental applications.

Fabrication of Crystalline Si Thin Films for Photovoltaics

Crystalline Si (c‐Si) thin films have been widely studied for their application to solar cells and flexible electronics. However, their application at large scale is limited by their fabrication process. As reviewed in this paper, many approaches have been studied, but only some of them have been made into large‐scale industrial production. The standard wire sawing of Si ingots cannot be scaled down to produce thin c‐Si wafers and films due to the brittle nature of c‐Si material, the resulting significant thickness variations, and the waste of material. Therefore, techniques based on the kerf‐less processes including “top‐down” and “bottom‐up” approaches have been developed in recent decades. In this review, photovoltaic applications of thin c‐Si wafers with thicknesses ranging from 50 μm down to 1 μm are presented first. Then, methods to fabricate c‐Si thin films based on both approaches are detailed, including slim‐cut, “smart‐cut,” epi‐free, as well as various growth processes such as molecular beam epitaxy, liquid phase epitaxy, ion beam, and chemical vapor deposition processes at a wide range of growth temperatures, from 1000 °C down to 150 °C. The advantages and disadvantages of these methods are presented and compared.

Fabrication of transparent wear-resistant superhydrophobic SiO2 film via phase separation and chemical vapor deposition methods

Glass with superhydrophobic, transparent, and wear-resistant properties are quite desirable for the applications in high building glass curtain, wind shield glass, and solar cell cover glass. How to fabricate a superhydrophobic surface with both high transparency and good wear resistance is still a great challenge because roughness and transparency are mutually exclusive. Here, transparent, wear-resistant, superhydrophobic inorganic coating on glass substrate has been successfully achieved by a two-step process combining phase separation and chemical vapor deposition (CVD). Firstly, a wear-resistant inorganic porous film with honeycomb-shaped pores is prepared on the glass surface by applying the phase separation method based on the epoxy resin-silica sol system. The prepared porous structure is used as the micron-level "armor" protective structure. Then nano-SiO2 particles have been deposited on the porous film via CVD method to construct a micro-nano hierarchical structure required for superhydrophobicity on the glass surface. Finally, a superhydrophobic film has been successfully achieved after being modified with fluoroalkylsilane (FAS). The water contact angle (WCA) and water sliding angle (WSA) of the obtained sample are 154.0 ± 0.9° and 3.2 ± 0.2°, respectively. At the same time, it has good transparency with high visible light transmittance and low haze. Its visible light transmittance is as high as 87.7% (only 1.7% less than blank glass) and haze is only 1.87%. Moreover, after 2000 cycles of abrasion under harsh conditions, the film still maintains good hydrophobic properties, and its water contact angle is still higher than 130°. In addition, the prepared functional film also has excellent self-cleaning performance, as well as acid and salt corrosion resistance. The preparation method used here has the advantages of low cost, easy operation, large area preparation, and broad application prospects.

Growing twisted bilayer graphene at small angles

Growing twisted bilayer graphene at small angles

Growth of centimeter scale Nb1−xWxSe2 monolayer film by promoter assisted liquid phase chemical vapor deposition

Growth of centimeter scale Nb1−xWxSe2 monolayer film by promoter assisted liquid phase chemical vapor deposition

Optoelectronic characteristics and application of black phosphorus and its analogs

The tunable bandgap from 0.3 eV to 2 eV of black phosphorus (BP) makes it to fill the gap in graphene. When studying the properties of BP more comprehensive, scientists have discovered that many two-dimensional materials, such as tellurene, antimonene, bismuthene, indium selenide and tin sulfide, have similar structures and properties to black phosphorus thus called black phosphorus analogs. In this review, we briefly introduce preparation methods of black phosphorus and its analogs, with emphasis on the method of mechanical exfoliation (ME), liquid phase exfoliation (LPE) and chemical vapor deposition (CVD). And their characterization and properties according to their classification of single-element materials and multi-element materials are described. We focus on the performance of passively mode-locked fiber lasers using BP and its analogs as saturable absorbers (SA) and demonstrated this part through classification of working wavelength. Finally, we introduce the application of BP and its analogs, and discuss their future research prospects.

Glass/Au Composite Membranes with Gold Nanoparticles Synthesized inside Pores for Selective Ion Transport.

Nanocomposite membranes have been actively developed in the last decade. The involvement of nanostructures can improve the permeability, selectivity, and anti-fouling properties of a membrane for improved filtration processes. In this work, we propose a novel type of ion-selective Glass/Au composite membrane based on porous glass (PG), which combines the advantages of porous media and promising selective properties. The latter are achieved by depositing gold nanoparticles into the membrane pores by the laser-induced liquid phase chemical deposition technique. Inside the pores, gold nanoparticles with an average diameter 25 nm were formed, which was confirmed by optical and microscopic studies. To study the transport and selective properties of the PG/Au composite membrane, the potentiometric method was applied. The uniform potential model was used to determine the surface charge from the experimental data. It was found that the formation of gold nanoparticles inside membrane pores leads to an increase in the surface charge from −2.75 mC/m2 to −5.42 mC/m2. The methods proposed in this work allow the creation of a whole family of composite materials based on porous glasses. In this case, conceptually, the synthesis of these materials will differ only in the selection of initial precursors.

Origin of ferromagnetism in Sm-doped In2S3 nanoparticles: Experimental and theoretical insights

Diluted magnetic semiconductors with room-temperature ferromagnetism (RTFM) opens new prospects for the development of next-generation spintronic devices. For now, the rare earth doping is an effective method to tune the ferromagnetism of semiconductor materials. In this work, we fabricated undoped In2S3 and In2S3: Sm3+ nanoparticles using gas-liquid phase chemical deposition method. UV–visible and photoluminescence spectra demonstrate that the introduction of Sm3+ ions lead to bandgap narrowing and enhanced luminescence intensity. Magnetic characterizations show that all synthetic samples display a ferromagnetic behaviour, and the maximum saturation magnetization of the samples can be tuned by regulating the concentration of doped Sm3+ ions. The RTFM in Sm doped In2S3 nanoparticles derives from the coupling interaction between the localized defect states and Sm3+ ions and is described using bound magnetic polarons (BMPs) mechanism. First-principle calculations reveal that In vacancies and Sm dopants are responsible for the generation of magnetic moments which come mainly from S 3p orbitals around the In vacancy and Sm 4f orbitals. Our results suggest that In2S3: Sm3+ nanoparticles constitute promising semiconductor materials for use in future electronic and spintronic devices.

Growth of 3D Nanoflower-Like FeCo2O4@Yb-Ni(OH)2 Composites on Ni Foam As Advanced Electrodes for High-Performance Supercapacitors

In this work, a 3D nanoflower-like Ni@FeCo2O4@Yb-Ni(OH)2 composite was prepared via a facile liquid phase chemical deposition and electrochemical deposition method. The as-synthesized Ni@FeCo2O4@Yb-Ni(OH)2 composites have a large specific surface area because of the developed nanoflower morphology, which creates good contact between the material and electrolyte. A high specific capacitance of 11.04 F·cm−2 is reached at a current density of 4 mA·cm−2. More importantly, the asymmetric supercapacitor assembled by using the as-synthesized Ni@FeCo2O4@Yb-Ni(OH)2 composites as the positive electrode and activated carbon as the negative electrode exhibits a high energy density of 36.86 Wh·kg−1, a power density of 1.2 kW·kg−1 and excellent cycling stability (97.8% capacitance retention).

“Kamchatite” diamond aggregate from northern Kamchatka, Russia: New find of diamond formed by gas phase condensation or chemical vapor deposition—Discussion

Article “Kamchatite” diamond aggregate from northern Kamchatka, Russia: New find of diamond formed by gas phase condensation or chemical vapor deposition—Discussion was published on January 1, 2020 in the journal American Mineralogist (volume 105, issue 1).

The influence of deposition technique of aluminide coatings on oxidation resistance of different nickel superalloys

The aluminizing is a basic method of surface protection of aircraft engine elements produced from nickel superalloys. In present article four methods of aluminide coatings deposition were used: pack cementation, above the pack/vapor phase aluminizing, slurry, and chemical vapor deposition (CVD). The selected superalloys: Inconel 100, Inconel 713 and MAR M247 were used as a base material. The Al concentration and thickness of aluminide coatings were analyzed on as-deposited coatings. The results of cyclic oxidation test at 1100 °C showed that aluminide coatings produced in low-activity CVD process was characterized by excellent corrosion resistance. It was a result of removing of impurities from coatings during low-activity CVD process.

Defect-induced room temperature ferromagnetism in Cu-doped In2S3 QDs.

The practical application of existing diluted magnetic semiconductors (DMSs) depends crucially on improving their room temperature ferromagnetism. Doping, as an effective method, can be used to modulate the physical properties of semiconducting materials. Herein, we report on the observation of significant RTFM in a III-VI semiconductor compound doped with nonmagnetic impurities, Cu-doped In2S3 quantum dots (QDs) grown by a gas-liquid phase chemical deposition method. The effect of Cu doping on the electronic structure and optical and magnetic properties of In2S3 is studied systematically. The UV-vis and photoluminescence (PL) spectra reveal that Cu-doped In2S3 can moderately benefit the optical properties of pristine In2S3. Magnetic measurements show that the pristine In2S3 and Cu-doped In2S3 QDs exhibit obvious RTFM, which is ascribed to the role of intrinsic defects in accordance with the bound-magnetic-polaron (BMP) theory. Furthermore, first-principles calculations based on the spin density functional theory indicate that In vacancies and their complexes with Cu dopants play a crucial role in inducing ferromagnetism. These results suggest that the Cu-doped In2S3 QDs are promising candidates for spintronics and magneto-optical applications.

INFLUENCE OF LIQUID-PHASE OXIDATIVE TREATMENTS ON STRUCTURE AND HYDROPHILITY OF CARBON NANOTUBES

Carbon nanotubes (CNTs) were synthesized by gas phase chemical deposition (CVD) using methane as a hydrocarbon reagent and using a catalyst of iron oxide deposited on fine aluminum oxide, as well as the same catalyst with the addition of molybdenum oxide deposited on fine magnesium oxide. The synthesized materials were treated with concentrated nitric acid (HNO3) or a mixture of concentrated nitric and sulfuric acids (HNO3 / H2SO4) in a volume ratio of 2: 1, at a temperature of 110-120 ° C for 1 h. Some of them were subjected to peroxide action (H2O2) before oxidative acid treatments for 1-2 h at a temperature of 100-110 ° C. Structural features, elemental compositions of synthesized CNTs were investigated before and after liquid-phase oxidative treatments by methods such as transmission electron microscopy, Raman spectroscopy, X-ray energy dispersive spectroscopy, X-ray phase analysis. In this work, the ability of CNTs that were undergone treatment in various oxidizing environments to form stable concentrated aqueous suspensions was studied. It was established that the initial defectity of the CNT molecules significantly affects the hydrophilic properties of oxidized CNT modifications. This causes their different ability to form concentrated, stable aqueous suspensions, predetermines the choice of combinations of oxidizing liquid-phase treatments that most contributing to this. It was revealed that HNO3 and HNO3 / H2SO4 mixture at the used temperature conditions of treatments and their duration do not have a strong destructive effect on the structure of CNT. The oxidative effect of these reagents on the molecules of this material is manifested mainly in defective places. The cleaning of the catalytic components of the synthesis from the catalytic components contributes to the more efficient purification of HNO3 / H2SO4 with the formation of stable aqueous suspensions from the molecules of this material, and this does not depend on the characteristics of the synthesis of the CNTs.

Laser-induced continuous generation of Ni nanoparticles for organic synthesis

The possibilities of laser-induced liquid phase chemical deposition (LCLD) of metal for continuous generation of nickel nanoparticles, the sizes of which allow their use as a catalyst for organic reactions are considered. The conditions for obtaining Ni nanoparticles by this method were optimized.

Fast triethylamine gas sensing response properties of Ho-doped SnO2 nanoparticles

Doping is benefical to the formation of defects on the surface and modification of the electronic structure of metal oxides. In this work, SnO2 nanoparticles (NPs) with different holmium ions concentrations of 0 at.%, 0.11 at.%, 0.45 at.%, and 0.53 at.% have been synthesized by a gas-liquid phase chemical deposition method with following annealing process. The SnO2:Ho3+ NPs exhibit superior triethylamine (TEA) gas sensing properties. The TEA sensing performance of the 0.45 at.% Ho-doped SnO2 NPs based sensor markedly improve compared with other different Ho doped based sensors. The response time for detecting 50 ppm TEA is only 2 s, and the response value is about 12. The as fabricated sensor shows fast response, excellent selectivity and reproducibility to TEA gas at a relatively low working temperature of 175 °C. Gas sensing testing shows that a suitable concentration of Ho doping leads to the enhancement of the sensor response. The enhanced sensing mechanism is attributed to the formation of oxygen vacancies and change of carrier concentration.

“Kamchatite” diamond aggregate from northern Kamchatka, Russia: New find of diamond formed by gas phase condensation or chemical vapor deposition

“Kamchatite” diamond aggregate from northern Kamchatka, Russia: New find of diamond formed by gas phase condensation or chemical vapor deposition