Thermal Chemical Vapor Deposition Research Articles

Synthesis and characterization of single‐walled carbon nanotube: Cyto‐genotoxicity in Allium cepa root tips and molecular docking studies

Herein, single-walled carbon nanotubes (SWCNTs) were synthesized by the thermal chemical vapor deposition (CVD) method, and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), Raman spectroscopy, dynamic light scattering (DLS), and thermo-gravimetric analysis (TGA). The results indicated that obtained nanotubes were SWCNTs with high crystallinity and their average diameter was 10.15 ± 3nm. Allium cepa ana-telophase and comet assays on the root meristem were employed to evaluate the cytotoxic and genotoxic effects of SWCNTs by examining mitotic phases, mitotic index (MI), chromosomal aberrations (CAs), and DNA damage. A. cepa root tip cells were exposed to SWCNTs at concentrations of 12.5, 25, 50, and 100 μg/ml for 4h. Distilled water and methyl methanesulfonate (MMS, 10μg/ml) were used as the negative and positive control groups, respectively. It was observed that MIs decreased statistically significantly for all applied doses. Besides, CAs such as chromosome laggards, disturbed anaphase-telophase, stickiness and bridges and also DNA damage increased in the presence of SWCNTs in a concentration-dependent manner. In the molecular docking study, the SWCNT were found to be a strong DNA major groove binder showing an energetically very favorable binding free energy of -21.27 kcal/mol. Furthermore, the SWCNT interacted effectively with the nucleotides on both strands of DNA primarily via hydrophobic π and electrostatic interactions. As a result, cytotoxic and genotoxic effects of SWCNTs in A. cepa root meristematic cells which is a reliable system for assessment of nanoparticle toxicology were demonstrated in this study.

Study on the Temperature Dependence of Three-dimensional Graphene Structure by Thermal Chemical Vapor Deposition

Study on the Temperature Dependence of Three-dimensional Graphene Structure by Thermal Chemical Vapor Deposition

熱化学気相成長（CVD）法による酸化タンタルナノ粒子の合成と光触媒水分解

熱化学気相成長（CVD）法による酸化タンタルナノ粒子の合成と光触媒水分解

Rhenium oxide/sulfide binary phase flakes decorated on nanofiber support for enhanced activation of electrochemical conversion reactions

Because of their versatile application potential, such as fuel cells and water electrolysis, boosting electrochemical half-cell reactions has been highlighted to realize energy conversion systems. However, sluggish multi-charge transfer reactions lower the energy efficiency for cell operation. Tailoring hierarchical catalyst nanostructures comprising heterogeneous crystalline phases allows for the improvement of limited activities and reaction performance. This study examines the controllable synthesis of heterogeneous rhenium oxide (ReOx) and rhenium sulfide (ReS2) nanoflakes vertically aligned on carbon nanofibers (CNFs) by thermal chemical vapor deposition (CVD). Their potential application as electrocatalysts in various electrochemical half-cell reactions for fuel cells and water electrolysis is elucidated. The phase portion of oxide and sulfide in the ReOx/ReS2 nanoflake-decorated CNF catalyst can be thermally tuned from an oxide-rich phase to a sulfide-rich phase, thereby optimizing the catalytic activities for hydrogen evolution (Eonset: −0.24 V) and oxygen reduction reactions (Eonset: 0.778 V, number of electron: 3.8), which is comparable to the performance of commercial Pt/C catalysts. The morphological and structural evolution mechanism of the ReOx/ReS2 nanoflake-decorated CNF catalyst materials is investigated using diverse material characterizations. This study suggests a synthetic method for temperature-dependent heterogeneous phase control of non-precious-metal-based hierarchical materials and offers a basis for developing efficient catalyst alternatives for application to sustainable energy conversion and storage systems.

Optimization of Growth Parameters of Thermal Chemical Vapor Deposition Method for 2D MoS2 Synthesis

Even after a decade of research on MoS2, it is still quite challenging to obtain high quality MoS2 films using a controlled synthesis technique. Out of all the available methods chemical vapor deposition (CVD) has proven to be a reliable technique to produce MoS2 thin films. The CVD growth process is sensitive to variety of parameters involved in the process. In the present work, we report the effect of pressure, temperature, gas flow, and position of substrate on the growth of MoS2 films. After several failures, the technique is optimized to synthesize high quality MoS2 films on quartz substrate. Further, the films are characterized using XRD, UV-Vis Spectroscopy, Photoluminescence Spectroscopy and Raman Spectroscopy. The main objective of this work is to formulate a method that produces MoS2 films using thermal CVD process by optimizing various parameters.

Fabrication of microlens arrays with high filling factors by combining a thermal reflow and parylene CVD technique and the applications on OLEDs.

In this paper, microlens array (MLA) templates with high filling factors were prepared by combining a thermal reflow method and parylene chemical vapor deposition (CVD). Then photoresist MLAs were replicated from the MLA templates by using ultraviolet nanoimprint technology. The surface morphology of the replicated photoresist MLAs was characterized by scanning an electron microscope and optical microscope. Results show that the photoresist MLAs have a relatively smooth surface, and the filling factor has been improved obviously. Also, the surface profiles of the MLAs were measured. The optical imaging properties of the MLAs were also characterized, and they had a relatively good imaging performance. Finally, the photoresist MLAs were applied on organic LEDs (OLEDs), and their luminance and current efficiencies were measured. Results show that the current efficiency of the OLEDs increased by about 42.41%, 29.01%, and 35.51%, respectively, for OLEDs with circular, hexagonal, and square MLAs. All the results above indicate that it is a simple and effective process to prepare MLA templates with high filling factors by combining thermal reflow and CVD techniques, and the prepared photoresist MLAs have great application potential in OLED areas.

Influence of the nucleation surface on the growth of epitaxial Al2O3 thermal CVD films deposited on cemented carbides

This work aims at understanding the nucleation and growth of alumina films grown on Ti(C,N)-based layers using an industrial-scale CVD system. Firstly, Al2O3 layer was deposited on Ti(C,N)-based layers without any nucleation treatment, pure α-Al2O3 is obtained, whereas no orientation relationship at the Ti(C,N)/α-Al2O3 layers interface can be observed. Secondly, Al2O3 layer was deposited on the bonding layer consisting of rutile TiO2, which is obtained by oxidizing the uppermost part of Ti(C,N)-based layers. Herein, α-Al2O3 single-phased layer is obtained, and the epitaxial growth of α-Al2O3 on rutile is observed. The orientation relationships can be found as:(1¯20)α-Al2O3//(101¯)rutile, (003)α-Al2O3//(010)rutile and [210]α-Al2O3//[101]rutile. Finally, Al2O3 layer was deposited on the bonding layer, produced from a TiCl4-H2-N2-CH4-CO-AlCl3 gas mixture. Regarding this intermediate layer, despite additions of CO and AlCl3, no evidence for oxide phases, e.g. TiO2 and Al2O3 can be found, while Ti(C,N) needle-shaped grains develop. In this case, κ-Al2O3 is epitaxially grown on Ti(C,N), with the orientation relationships found as:.(01¯3)κ-Al2O3//(2¯20)Ti(C,N), (100)κ-Al2O3//(1¯1¯1)Ti(C,N) and [031]κ-Al2O3//[112]Ti(C,N). Since processing parameters for the alumina depositions were always the same, it is revealed that the nucleation of α-Al2O3 and κ-Al2O3 can be accurately controlled with deposition of specific bonding layers.

Screen-Printing of Functionalized MWCNT-PEDOT:PSS Based Solutions on Bendable Substrate for Ammonia Gas Sensing.

Multi-walled carbon nanotubes (MWCNTs) were grown on a stainless-steel foil by thermal chemical vapor deposition (CVD) process. The MWCNTs were functionalized with carboxylic groups (COOH) on their surfaces by using oxidation and acid (3:1 H2SO4/HNO3) treatments for improving the solubility property of them in the solvent. The functionalized MWCNTs (f-MWCNTs) were conducted to prepare the solution by continuous stir in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), dimethyl sulfoxide (DMSO), ethylene glycol (EG) and Triton X-100. The solution was deposited onto a bendable substrate such as polyethylene terephthalate (PET) with a fabricated silver interdigitated electrode for application in a room-temperature gas sensor. A homemade-doctor blade coater, an UNO R3 Arduino board and a L298N motor driver are presented as a suitable system for screen printing the solution onto the gas-sensing substrates. The different contents of f-MWCNTs embedded in PEDOT:PSS were compared in the gas response to ammonia (NH3), ethanol (C2H5OH), benzene (C6H6), and acetone (C3H6O) vapors. The results demonstrate that the 3.0% v/v of f-MWCNT solution dissolved in 87.8% v/v of PEDOT:PSS, 5.4% v/v of DMSO, 3.6% v/v of EG and 0.2% v/v of Triton X-100 shows the highest response to 80 ppm NH3. Finally, the reduction in the NH3 response under heavy substrate-bending is also discussed.

Evolution of Nanostructured Carbon Coatings Quality via RT-CVD and Their Tribological Behavior on Nodular Cast Iron

One of the most critical problems in industry is the wear of materials. Graphene, as a tribological coating, has shown a tremendous impact on sliding surfaces. In this work, a few layers of graphene were grown on a nodular cast iron substrate, a material used in camshafts. The studied synthesis parameters in a rapid thermal chemical vapor deposition (CVD) furnace and the quality of the final coating are presented. The influence of hydrogen flow and cooling rate was evaluated, obtaining the best results in the few layers of graphene structure and deposition at 10 sccm and 4 °C/min. A standard ball-on-disk tribometer was used to assess the coefficient of friction on a few layers of graphene on nodular cast iron substrates. Laboratory test results show that the few layers of graphene coating resulted in a 60% reduction in coefficient of friction and close to a 70% reduction in volume removed versus the uncoated substrates. The surface of the substrate was not modified before a few layers of graphene growth to have a working surface close to camshafts obtained by the industrial process at ARBOMEX SA de CV.

Characterizing and Analyzing the Tribological Behaviour of Diamond Coated Tungsten Carbide (WC)

In this research work, the deposition of diamond coating was done on the tungsten carbide (WC) substrate utilizing the the thermal Chemical Vapour Deposition (CVD) technique. The carbon precursor used for growing the diamond on the tungsten carbide (WC) substrate material was sugarcane bagasse. The tribological properties of deposited diamond coating were studied examined in this paper. For characterization of the developed coating, Field Emission Scanning Electron Microscope (FESEM), Raman spectroscopy and X-ray diffraction (XRD), were used to characterize the developed diamond coating on the substrate material. These processes were used to confirm the presence of diamond coating on the substrate. For inspecting the hardness of the developed diamond coated and un coated samples, the tests of micro-hardness were also executed. The values of the Vickers hardness for the un-coated and the diamond coated substrates were found to be 964.95 HV to 1457.48 HV respectively. This depicted a rise of 51% in the hardness of the un-coated WC inserts. As per ASTM G-99 standards tribological behaviour of the developed coated substrate was also the scope of this work using a pin-on-disc tribometer. The tribological tests showed improvement in the wear resistance of the diamond coated WC inserts as there was a decrease in the value of wear by 57.84 %. The value of the coefficient of friction (COF) also found to be decreased by 51.48%. This paper presents a combined study of using tribological tests and morphologic study showing the advantages of coating diamond on the tungsten carbide (WC) substrate.

Combined synthesis of carbon nanospheres and carbon nanotubes using thermal chemical vapor deposition process

Carbon spheres (CNSs) and carbon nanotubes (CNTs) are attracting more attention from researchers due to their excellent potential applications as adsorbents, catalyst carriers, and drug delivery. The synthesizing of CNTs and CNSs is a challenging and tedious process. A researcher has to produce different catalyst materials and precursors to synthesize CNTs and CNSs. Hence, an attempt has been made to combined in-situ synthesize of CNSs and CNTs in a single experiment. NiO/CuO/Al2O3 catalyst was used as a substrate. The thermal chemical vapor deposition (CVD) process with acetylene as a precursor gas was used to synthesize the CNSs and CNTs. The influence of process parameters and the growth mechanism of carbon nanomaterials were investigated. The obtained carbon nanomaterials samples were characterized using FESEM, HRTEM with SAED pattern, XRD analysis, Raman spectroscopy, and FTIR analysis. Results indicated that the catalyst morphology has a greater influence on the growth of CNTs and CNSs. The CVD process parameters play a vital role in deciding the structure of carbon nanomaterials. A schematic representation was proposed to understand the formation of carbon nanomaterials on top of the catalyst particles.

Porous composites of vertical graphene sheets and Fe3O4 nanorods grown on Fe/Fe3C particle embedded graphene-structured carbon walls for highly efficient microwave absorption

It is significantly important but remains challenging to prepare high performance microwave absorption materials in civil and military fields. Here, the Fe/Fe3C particles embedded in graphene-structured porous carbon (FGPC) served as a three-dimensional framework is prepared by simple carbothermal reduction, then vertical graphene nanosheets (VGSs) and Fe3O4 nanorods are successively grown on FGPC (FGPC/VGSs and FGPC/VGSs/Fe3O4) by thermal chemical vapor deposition, solution method, and subsequent heat treatment. As for comparison, VGSs and Fe3O4 nanorods grown on GPC without Fe/Fe3C particles (GPC/VGSs and GPC/VGSs/Fe3O4) are also prepared. The microwave absorption properties of them are investigated. Benefiting from the multi-component integration and well-designed structure, the FGPC/VGSs/Fe3O4 exhibits impressive microwave absorption performance with an optimal reflection loss of −64.7 dB at 15.3 GHz, a matching thickness of 1.7 mm, filler loading of 12 wt%, and effective absorption bandwidth of over 4.8 GHz. This results from the balance of impedance match and attenuation capability. In detail, the introduction of magnetic particles and nanorods improves the impedance match. The multiple reflections and scatterings, moderate conductive loss and magnetic loss enhance the attenuation of microwaves. Thus, this work might open an avenue to design a highly efficient and lightweight multi-dimensional multiple component microwave absorbers.

Sulfurized Steel Nanoparticles: A Degradative Byproduct of ZrS2CVD with Promising Fenton‐Type Catalytic Activity

AbstractChemical vapor deposition (CVD), is an attractive method for the growth of two‐dimensional (2D) materials such as transition metal dichalcogenides (TMDCs). However, it is an inherently wasteful process; the majority of chemical precursors end up in the waste stream and their corrosive nature deteriorates reactor components. While exploring the thermal CVD growth of ZrS2, the resulting corrosion build up on the downstream stainless‐steel (SS) reactor components was collected and studied. Characterization of this material confirmed the presence of nanoplates composed of evenly distributed elements that constitute SS along with Cl, S, and trace Zr from the precursors. The material proved remarkably active as a photo‐Fenton type catalyst for the aqueous degradation of methylene blue. Harvesting and upcycling this overlooked nanomaterial will reduce waste and concomitantly add value and enhance the sustainability of the overall TMDC fabrication process.

Growth of vertically aligned BN nanosheets via Fe-catalyzed thermal chemical vapor deposition

Hexagonal boron nitride nanosheets (BNNSs) demonstrated potential applications for ultraviolet (UV) nanoelectronics, catalytic support, electron field emission, and many other areas. However, their extensive industrial application is limited by the complicated conventional procedures for scalable preparations. In this study, vertically aligned BNNSs were directly synthesized without any substrates using Fe-catalyzed thermal chemical vapor deposition (CVD) method under a NH 3 gas flow at 1200 °C via the catalytic pyrolysis of the inorganic hybrid precursor. BNNSs grew via an Oswald ripening process assisted by oriented attachment mechanism under Fe catalyzed by analyzing the evolution process. Most nanosheets are <10 nm thick, and the number of constituent layers is typically between 10 and 20 nm. BNNSs improved crystallinity, had high UV light emission, and had excellent anti-oxidation behavior because of their unique structures. The development of a simple, high yield and environmentally friendly synthesis method for BNNSs allows for the exploration of industrial upscaling applications. • Vertically aligned BNNSs deposited by a catalytic-thermal CVD route without substrates. • The inorganic precursor was prepared by a sample wet chemical synthesis methods. • BNNSs exhibited enhanced crystallinity and UV light emission as well as remarkable oxidation resistance. • BNNSs grow via an Oswald ripening process assisted by the oriented attachment mechanism.

Formation of Thermally Stable, High-Areal-Density, and Small-Diameter Catalyst Nanoparticles via Intermittent Sputtering Deposition for the High-Density Growth of Carbon Nanotubes.

We report the formation of thermally stable catalyst nanoparticles via intermittent sputtering deposition to prevent the agglomeration of the nanoparticles during thermal chemical vapor deposition (CVD) and for the high-density growth of carbon nanotubes (CNTs). The preparation of high-areal-density and small-diameter catalyst nanoparticles on substrates for the high-density growth of CNTs is still a challenging issue because surface diffusion and Ostwald ripening of the nanoparticles induce agglomeration, which results in the low-density growth of large-diameter CNTs during high-temperature thermal CVD. Enhancing the adhesion of nanoparticles or suppressing their diffusion on the substrate to retain a small particle diameter is desirable for the preparation of thermally stable, high-areal-density, and small-diameter catalyst nanoparticles. The intermittent sputtering method was employed to deposit Ni and Fe metal nanoparticles on a substrate for the synthesis of high-areal-density CNTs for Fe nanoparticle catalyst films. The metal particles deposited via intermittent sputtering with an interval time of over 30 s maintained their areal densities and diameters during the thermal CVD process in a vacuum for CNT synthesis. An interval of over 30 s was expected to oxidize the metal particles, which resulted in thermal stability during the CVD process. The intermittent sputtering method is thus a candidate process for the preparation of thermally stable catalyst films for the growth of a high density of long CNTs, which can be combined with the present CNT production process.

Enhanced thermal transport and corrosion resistance by coating vertically-aligned graphene on zirconium alloy for nuclear reactor applications

Owing to the requirement of higher efficiency, safety reliability and lower maintenance cost for nuclear reactors, the performance improvement of zirconium (Zr) alloy cladding coating materials is becoming increasingly significant. Graphene, with its inherent properties like ultrahigh thermal conductivity, excellent chemical stability, and super-hydrophobicity, has demonstrated enormous potential in the field of corrosion prevention and thermal management, indicating its promising application in cladding materials. Herein, plasma-enhanced chemical vapor deposition (PECVD) was employed for growing vertically-aligned graphene (VG) array on Zr alloy (ZA) substrates. In the deposition process, C2H4 gas was introduced into the reactor as the carbon source and the reactor was kept at a growth temperature range of 650–800 °C, which is 300–400 °C lower than that for traditional graphene synthesis using thermal chemical vapor deposition (CVD). The effects of other growth experimental parameters such as gas flow ratio, radio-frequency power (RF-power), growth temperature, reaction pressure and deposition time were systematically investigated. The corrosion resistance and thermal transport performance of vertical graphene enhanced Zr alloy (VGZA) were studied by using electrochemical corrosion method and heat dissipation test system. The results showed that the samples loaded with vertical graphene could effectively improve the corrosion resistance and heat transport property.

Defect- and H-Free Stoichiometric Silicon Carbide by Thermal CVD from the Single Source Precursor Trisilacyclohexane

Stoichiometric silicon carbide (SiC) thin films were grown using thermal chemical vapor deposition (TCVD) from the single source precursor 1,3,5-trisilacyclohexane (TSCH) on c-Si (100) substrates within an optimized substrate temperature window ranging from 650 to 850 °C. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analyses revealed that the as-deposited films consisted of a Si-C matrix with a Si:C ratio of ~1:1. FTIR and photoluminescence (PL) spectrometry studies showed that films deposited ≥ 750 °C were defect- and H-free within the detection limit of the techniques used, while ellipsometry measurements yielded an as-grown SiC average refractive index of ~2.7, consistent with the reference value for the 3C-SiC phase. The exceptional quality of the films appears sufficient to overcome limitations associated with structural defects ranging from failure in high voltage, high temperature electronics to 2-D film growth. TSCH, a liquid at room temperature with good structural stability during transport and handling as well as high vapor pressure (~10 torr at 25 °C), provides a viable single source precursor for the growth of stoichiometric SiC without the need for post-deposition thermal treatment.

Tuning mechanical and corrosion performance of SiOC glass coatings prepared by thermal MOCVD

In this study, silicon oxycarbide (SiOC) glass coatings were successfully deposited by thermal metal organic chemical vapor deposition (MOCVD). The composition, chemical bonding and mechanical properties of the prepared SiOC glass coatings were studied using X-ray photoelectron spectroscopy (XPS) and nano indentation techniques. The surface morphologies of SiOC coatings were characterized by field emission scanning electron microscopy (FESEM) before and after etching with HF acid for prolong time. The results showed that the percentage of Si-C bonds in SiOC glass coatings increases with increasing the content of HMDS in liquid precursors mixture. Raman spectroscopy results revealed the presence of amorphous carbon (with high content of sp3 bonds) in the prepared SiOC coatings. Consequently, the hardness and modulus of SiOC glass coatings increased from 8.99 GPa and 82.6 GPa to 17.93 GPa and 195.6 GPa, respectively. Further, the prepared SiOC glass coatings exhibited excellent corrosion resistance against HF acid.

Dual role of N-doped graphene film as a cathode material for anodic organic oxidation and persulfate production and as a planar carbocatalyst for non-electrochemical persulfate activation

In this study, a large-area N-doped graphene film (NG/NF) was fabricated on a nickel foam (NF) substrate via thermal chemical vapor deposition along with the flow of gaseous C2H4/NH3 mixtures.

Highly enhanced field emission from vertically aligned carbon nanotubes grown on a patterned substrate via non-lithographic method

In the present work, a silicon substrate has been patterned with a gold thin film of thickness 15 nm using thermal evaporation , followed by growth of carbon nanotubes (CNTs) using thermal chemical vapor deposition . The effect of temperature on the growth of CNTs on Au patterned substrate is studied using Raman and Field emission scanning electron microscope (SEM). A significant change in the growth of the CNTs grown on Au film patterned substrate with temperature can be observed using SEM images. However, no significant change in the micro crystallinity of the films was observed. Field emission properties of vertically aligned carbon nanotubes, grown at different temperatures, on gold film patterned substrate has been investigated. For the non-patterned substrate, for the CNT film grown at 900 °C, the current density comes out to be 8.0 mA/cm 2 @ 4.8V/μm, which increases to 14.6 mA/cm 2 in the case of CNT film grown on gold patterned substrate. The observed enhancement of nearly 180% in current density for the patterned substrate as compared to non-patterned silicon substrate is primarily attributed to the reduced electric field screening. The reduced screening is realized with the help of COMSOL simulation, showing a significant enhancement in the local electric field near edges. • Use of novel non- Lithographic technique to pattern CNT films. • Effect of temperature on the Growth of vertically aligned CNTs on patterned substrate. • Nearly 180% enhancement in Field emission current density for CNTs grown over patterned substrate at 900 °C. • Simulation based verification of enhancement in the Field emission properties due to reduced screening.