Simple Vapor Deposition Method Research Articles

Sintered glass filter as a membrane impregnated with g-C3N4 and AuAg/g-C3N4 to degrade Rhodamine B with application in decentralized areas

This work shows a novel approach utilizing graphitic carbon nitride (g-C3N4) deposited on a sintered glass filter as a membrane enhanced with gold-silver nanoparticles for the removal of emerging pollutants. g-C3N4 was synthesized directly onto the membrane surface with a simple vapor deposition method. Membranes with two different porosities, g-C3N4 and the noble-metal nanoparticles were put to the test by exploring their photocatalytic capacity to degrade rhodamine B dye (RhB). FT-IR, PL, SEM, EDX and DRS characterization techniques were performed to analyse the catalysts. RhB degradation was tested in static (i.e. petri dish) and dynamic conditions (i.e. photocatalytic membrane setup). Filtered volumes, turbidity effect and stability were tested in dynamic conditions for the membrane that had the greatest potential for full-scale use. The results confirm the efficient RhB degradation capacity of the catalysts, highlighting the potential of this proposed setup; however, the cost of technology for decentralized areas is still an impediment. These findings not only contribute to advancing the understanding of pollutant removal technologies, but also, offer practical insights into the future deployment of such systems on a larger scale.

A Highly Selective Acetone Sensor Based on Coal-Based Carbon/MoO2 Nanohybrid Material.

High temperature represents a critical constraint in the development of gas sensors. Therefore, investigating gas sensors operating at room temperature holds significant practical importance. In this study, coal-based porous carbon (C-700) and coal-based C/MoO2 nanohybrid materials were synthesized using a simple one-step vapor deposition and sintering method, and their gas-sensing performance was investigated. The gas-sensing performance for several VOC gases (phenol, ethyl acetate, ethanol, acetone, triethylamine, and toluene) and a 95% RH high-humidity environment were tested. The results indicated that the C/MoO2-450 sample sintered at 450 °C exhibited excellent specific selectivity towards acetone at room temperature, with a response value of 4153.09% and response/recovery times of 10.8 s and 2.9 s, respectively. Furthermore, the C/MoO2-450 sample also demonstrated good repeatability and long-term stability. The sensing mechanism of the synthesized materials was also explored. The superior gas-sensing performance can be attributed to the synergistic effect between the porous carbon and MoO2 nanoparticles. Given the importance of enhancing the high-tech and high-value-added utilization of coal, this study provides a viable approach for utilizing coal-based carbon materials in detecting volatile organic compounds at room temperature.

A durable, fluorine-free, and repairable superhydrophobic aluminum surface with hierarchical micro/nanostructures and its application for continuous oil-water separation

Artificial superhydrophobic surfaces have drawn a lot of attention owing to their multifunctional properties. However, the durability and environmental concerns of such surfaces are critical issues that have limited their widespread utilization in real-life applications. In this study, fluorine-free superhydrophobic aluminum surface was fabricated through a simple and cost-effective method. Its dual-scale micro-/nanostructures (MNS) was fabricated by combining chemical etching and hydrothermal processes. After modification with polydimethylsiloxane coating using a simple vapor deposition method, surface showed excellent superhydrophobicity, with a water contact angle of ~161° and sliding angle of 4°, and sustained its non-wetting properties against various food liquids. The effect of morphological change on the surface's wettability and the durability of the coating materials were investigated in sandpaper abrasion, tape-peeling, and blade-scratching tests. Compared with micro- or nanostructure surfaces, the MNS surface showed better robustness because of its dual-scale roughness. Furthermore, the abraded surface could effectively restore its superhydrophobicity after being recoated with PDMS. The surface also showed long-term superhydrophobic stability in an ambient environment for over 10 months. Finally, the method was applied to Al mesh with superhydrophobic/superoleophilic properties to separate various oil-water mixtures, yielding a high separation efficiency of up to 94% and outstanding reusability.

Surface modification of ZnO nanowire arrays with PTFE and their wettability property

Super-hydrophobic materials are important for their self-cleaning function which has become an increasingly popular research topic. This special surface in biologic world with super-hydrophobicity gives us a lot of inspiration to produce artificial hydrophobic materials to be applied in daily life and industry. Coating polytetrafluoroethylene (PTFE) on ZnO nanowire arrays is believed an ideal structure to produce a super hydrophobic surface layer. However, it is still a challenge to well combine PTFE and ZnO nanowires with high durability by a simple method. In this paper, we studied the wettability property of the surface modified ZnO nanowire arrays. These vertically ordered and well crystallized ZnO nanowire arrays were synthesized by a microwave-assisted hydrothermal method. After coating a thin layer of PTFE on those ZnO nanowire arrays by a simple vapor deposition method, the surface of samples has excellent super hydrophobicity with extremely low water rolling angle. The experimental results testify the modified ZnO nanowires have a good self-cleaning surface.

Robust and Chemically Stable Superhydrophobic Aluminum-Alloy Surface with Enhanced Corrosion-Resistance Properties

We report a simple method for fabricating micro-nanoscale structures consisting of irregular microscale plateaus with a self-assembled network of zinc oxide nanopetals on an aluminum alloy substrate. The method involves a combination of chemical etching with a hydrothermal process, followed by Polydimethylsiloxane coating via a simple vapor deposition method. Following the coating, surface displays superhydrophobicity with water contact angle of 161° and a sliding angle of 4°. The effect of morphological changes on wettability is examined by varying the hydrothermal processing time. The chemical stability of the superhydrophobic surfaces is examined in a wide range of corrosive media. After being immersed in a 3.5 wt% NaCl solution for 1 month, the surface retained its superhydrophobicity. The potentiodynamic polarization test results reveal that the superhydrophobic surface highly improves the corrosion resistance performance of the bare aluminum surface by three orders of magnitude. In addition, surface exhibited good mechanical durability against sandpaper abrasion, and long-term stability in the ambient environment. The proposed fabrication technique operating at relatively low temperature is simple and provides a new approach for production of large-scale three-dimensional superhydrophobic surfaces for various applications.

Ultrafine polycrystalline titania nanofibers for superior sodium storage

Abstract Sodium ion batteries have a huge potential for large-scale energy storage for the low cost and abundance of sodium resources. In this work, a novel structure of ultrafine polycrystalline TiO2 nanofibers is prepared on nickel foam/carbon cloth by a simple vapor deposition method. The as-prepared TiO2 nanofibers show excellent performance when used as anodes for sodium-ion batteries. Specifically, the TiO2 nanofibers@nickel foam electrode delivers a high reversible capacity of 263.2 mAh g−1 at 0.2 C and maintains a considerable capacity of 144.2 mAh g−1 at 10 C. The TiO2 nanofibers@carbon cloth electrode also shows excellent high-rate capability, sustaining a capacity of 148 mAh g−1 after 2000 cycles at 10 C. It is believed that the novel nanofibrous structure increases the contact area with the electrolyte and greatly shortens the sodium ion diffusion distance, and meanwhile, the polycrystalline nature of nanofibers exposes more intercalation sites for sodium storage. Furthermore, the density functional theory calculations exhibit strong ionic interactions between the exposed TiO2 (101) facets and sodium ions, leading to a preferable sodiation/desodiation process. The unique structural features endow the TiO2 nanofibers electrodes great advantages in rapid sodium storage with an outstanding high-rate capability.

Formation of GaN thin film on silicon substrate by gallium oxide ammoniation

Gallium Nitride (GaN) thin film was successfully grown by ammoniation of the chemically vapour deposited Gallium oxide (Ga2O3) through the nitridation process. Ga2O3 was deposited on silicon substrate using simple vapor deposition method in a tubular furnace. The nitridation of the deposited layer was achieved at low temperature of 1273 K. The structural, optical, morphological and electrical properties of the as grown GaN thin film was studied by X-ray diffraction, SEM, AFM, Photoluminescence and I–V characteristics. The result revels that the grown thin film have a wurtzite crystal structure with a layer thickness of ∼5 μm and roughness of about 0.3 nm. Photoluminescence spectra show broad emission peak with various peaks associated in it. Corresponding I–V characteristics of the GaN schottky diode was recorded and the ideality factor was calculated. Photo response of the fabricated diode was also recorded.

Modification of graphene electronic properties via controllable gas-phase doping with copper chloride

Molecular doping is an efficient, non-destructive, and simple method for changing the electronic structure of materials. Here, we present a simple air ambient vapor deposition method for functionalization of pristine graphene with a strong electron acceptor: copper chloride. The doped graphene was characterized by Raman spectroscopy, UV-vis-NIR optical absorption spectroscopy, scanning electron microscopy, and electro-physical measurements performed using the 4-probe method. The effect of charge transfer from graphene to a dopant results in shifting the Fermi level in doped graphene. The change of the electronic structure of doped graphene was confirmed by the tangential Raman peak (G-peak) shift and by the appearance of the gap in the UV-vis-NIR spectrum after doping. Moreover, the charge transfer resulted in a substantial decrease in electrical sheet resistance depending on the doping level. At the highest concentration of copper chloride, a Fermi level shift into the valence band up to 0.64 eV and a decrease in the sheet resistance value by 2.36 times were observed (from 888 Ω/sq to 376 Ω/sq for a single graphene layer with 97% of transparency).

Fabrication of Hybrid Silicate Coatings by a Simple Vapor Deposition Method for Lithium Metal Anodes

AbstractLithium metal anodes are highly promising for next‐generation rechargeable batteries. However, implication of lithium metal anodes is hampered by the unstable electrochemical behavior. Herein, the fabrication of hermetic coatings of hybrid silicate on lithium metal surface using a simple vapor deposition technique under the ambient condition is reported. Such coatings consist of a “hard” inorganic moiety that helps to suppress lithium dendrites and a “soft” organic moiety that enhances the toughness. Lithium metal batteries, including Li–LiFePO4 and Li–S batteries, made with such coated anodes show significantly improved lifetime. This work provides a simple yet effective approach to stabilize lithium metal anodes for high‐performance lithium metal batteries.

Controllable Synthesis of Zn<sub><em>x</em></sub>Cd<sub>1-<em>x</em></sub>S Nanowires with Tunable Optical Properties

ZnxCd1-xS (0<x<1) nanowires with several different compositions were successfully synthesized on Si wafers by a simple vapor deposition method using Au as a catalyst. The morphology and composition of the nanowires were investigated by scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy. The results show that the Zn/Cd ratio is controllable by adjusting the relative amount of the starting materials and the deposition temperature. The Xray diffraction patterns show that the nanowires are single crystals with the wurtzite structure. The morphology character of the nanowires suggests that the growth of the nanowires can be explained by the base-growth mechanism. The optical characteristics of the nanowires were studied by Raman and photoluminescence (PL) spectroscopy. Raman shifts of the longitudinal optical (LO) phonon mode were observed in the ZnxCd1xS nanowires. The LO peak frequency changed smoothly with changing composition, which approximately shows a one-mode behavior pattern in the ZnxCd1xS nanowires. In the PL spectra, both band-gap and defect emission were observed. The PL results indicate that the emission frequency originating from the band-gap transition of the ZnxCd1xS nanowires can be tuned through modulating of the composition. The band-gap of the nanowires can be tuned from 2.41 eV (CdS) to 3.63 eV (ZnS). 576 LIN Xu-Feng et al.: Controllable Synthesis of ZnxCd1-xS Nanowires with Tunable Optical Properties No.3

Controllable growth of laterally aligned zinc oxide nanorod arrays on a selected surface of the silicon substrate by a catalyst-free vapor solid process – a technique for growing nanocircuits

We report a simple and effective vapor deposition method for directly growing ultra-long, laterally aligned, zinc oxide (ZnO) nanorod arrays only on the side edges of a bare silicon (Si) substrate without using any catalysts and precursors. The growth on the top surface of the substrate is restrained by controlling the flow of source vapor in a tube furnace through the chemical vapor solid process. The optimized growth parameters have been thoroughly investigated and identified. Direct growth of laterally aligned ZnO nanowire arrays on the desired surface of the substrate is successfully achieved. A vapor solid mechanism with source vapor flow rate control has been proposed to explain the synthesis: ZnO nanodots first form on the bare Si substrate side edges due to the local large binding energy and high zinc (Zn) vapor concentration, and then nanorods epitaxially grow from the nanodots. In addition, the lateral, ultra-long ZnO nanorods grown on orthogonal silicon microelectrodes are achieved and could be expected to find important applications in a bottom-up way of fabricating the next generation nanoelectronics.

Fabrication of Graphene Directly on SiO2without Transfer Processes by Annealing Sputtered Amorphous Carbon

We fabricated multilayer graphene directly on SiO2 by annealing sputtered amorphous carbon with a catalyst – a simple non-chemical vapor deposition method – without the use of complicated transfer processes. Structural analysis revealed that the graphene sheets formed an epitaxial structure aligned to the Co(111) surface between the Co catalyst and SiO2 dielectric. In the multilayer graphene, a resistivity of approximately 500 µΩ cm was obtained, which is one order of magnitude higher than that of highly oriented pyrolytic graphite.

Fabrication of Graphene Directly on SiO2 without Transfer Processes by Annealing Sputtered Amorphous Carbon

We fabricated multilayer graphene directly on SiO2 by annealing sputtered amorphous carbon with a catalyst – a simple non-chemical vapor deposition method – without the use of complicated transfer processes. Structural analysis revealed that the graphene sheets formed an epitaxial structure aligned to the Co(111) surface between the Co catalyst and SiO2 dielectric. In the multilayer graphene, a resistivity of approximately 500 µΩ cm was obtained, which is one order of magnitude higher than that of highly oriented pyrolytic graphite.

Synthesis of Antimony‐Based Nanowires Using the Simple Vapor Deposition Method

III-V nanowires have attracted plenty of attention because of their potential outstanding performance in a wide range of applications. However, compared to other III-V nanowires, the synthesis of high quality Sb-based nanowires is less developed, which obstructs the progress towards further applications. In this study we report high quality GaSb and InSb nanowires synthesized by a simple vapor deposition method. Epitaxial growth of nanowires on growth substrates is demonstrated. Te doped GaSb nanowires are achieved through in situ doping during the vapor deposition process. Electrical measurements of nanowire field-effect transistors show high performance of the synthesized InSb nanowires.

In-Situ Phosphrous Doping in ZnTe Nanowires with Enhanced p-type Conductivity

Single-crystalline undoped and phosphrous-doped (P-doped) p-type ZnTe nanowires (NWs) were synthesized via a simple vapor transport and deposition method. Both undoped and P-doped ZnTe nanowires have zinc blende structure and uniform geometry. X-ray diffraction peaks of the P-doped ZnTe nanowires show an obvious shift toward higher diffraction angle as compared with the undoped ZnTe nanowires. X-ray photoelectron spectroscopy confirms the existence of P-dopant in the ZnTe nanowires. Field-effect transistors based on both undoped and P-doped ZnTe nanowires were fabricated and characterized. Electrical measurements demonstrated that P-doping led to an enhancement in ptype conductivity of ZnTe nanowires. A defect reaction mechanism was proposed to explain the p-type behaviors of both undoped and P-doped ZnTe nanowires.

Amplified spontaneous emission from single CdS nanoribbon with low symmetric cross sections

CdS nanoribbons with various cross sections offer the opportunity to deeply understand the interaction between optical cavity and spontaneous emission. Herein, long tapered nanoribbons with the cross sections gradually changing were synthesized by a simple physical vapour deposition method. Morphology dependent micro-region photoluminescence (PL) spectroscopy is employed to show Purcell effect along different low symmetry cross sections. Spikes on the PL spectra reveal that local density of optical modes increases when the mode match happens between optical cavity and spontaneous emission. Bound exciton complex related amplified spontaneous emission is observed in a single CdS nanoribbon with well-defined elliptical cross sections and optimized width/thickness ratio ∼1.45. Polarized Raman and TEM confirmed that the nanoribbon with the elliptical cross section adopts the [0002] growth direction with good quality. The results suggest that the cross section resonant cavity would be of importance for both fundamental and practical application of cavity quantum electrodynamics in CdS nanoribbon.

Core‐shell SiC/SiO2 heterostructures in nanowires

AbstractThis paper presents a simple vapour deposition method for one‐step synthesis of SiC//SiO2 core‐shell heterostructured nanowires. The phases, structures and morphologies of the synthesized core‐shell heterostructures are systemically studied by field emission scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, and high‐resolution transmission electron microscopy. The results show that these heterostructures consist of a single crystalline SiC core of 20∼30 nm diameter covered by a uniform layer, about 15 nm thickness of amorphous SiO2. Such heterostructures were grown based on the vapour–solid mechanism and the deposition way has an important influence on their morphology. A unique optical property has also been found in their photoluminescence spectra that have blue shift relative to the bulk SiC.

Single-crystalline ZnTe nanowires for application as high-performance Green/Ultraviolet photodetector

Single-crystalline ZnTe nanowires were prepared by a simple vapor transport and deposition method. Photodetectors of individual ZnTe nanowires were fabricated to study photoconductivity of the nanowires. It was observed the nanowire photodetectors show the highest visible-light photoconductive gains among all reported photodetectors based on 1D nanostructure semiconductors, including CdS, CdSe, ZnSe, etc. The high photosensitivity and relatively fast response speed are attributable to the high crystal quality of the ZnTe nanowires. These results reveal that such single-crystalline ZnTe nanowires are excellent candidates for optoelectronic applications.

Microstructure and Photoluminescence Studies of Sb-Doped SnO2 Zigzag Nanobelts

SnO2 zigzag nanobelts were successfully Sb-doped by a simple vapor deposition method. Field emission scanning electron microscope (FESEM), high resolution transmission electron microscope (HRTEM), and X-ray diffraction (XRD) were used to characterize these Sb-doped nanobelts. The Sb doping in SnO2 nanobelts was confirmed by Energy Dispersive X-ray spectrum (EDS) and X-ray photoelectron spectroscopy (XPS). It is found that there is no apparent lattice distance difference between the pure SnO2 and the 0.705 at% Sb doped SnO2 nanobelts. A slight blue-shift in the photoluminescence (PL) spectra was shown with the increase of Sb doping concentration and a reasonable explanation was given.

Synthesis and Characterization of Hexagonal and Truncated Hexagonal Shaped MoO3 Nanoplates

Hexagonal and truncated hexagonal shaped MoO3 nanoplates (MoO3 HNP) were synthesized through a simple vapor-deposition method in Ar atmosphere under ambient pressure without the assistant of any catalysts. The structure and morphology of MoO3 HNP were investigated by XRD, EDX, SEM, TEM, and HRTEM. The results reveal that the HNP are α-MoO3 and have a large area surface. The Raman spectrum shows a significant size effect on the vibrational property of MoO3 HNP. The photoluminescence (PL) spectrum was carried out, and two peaks at 351 and 410 nm were observed in the spectrum. In addition, a possible growth mechanism proposed as VS is discussed in detail.