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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. [ABSTRACT FROM AUTHOR]

In this report, we propose an easy and viable fabrication method for growing multilayer graphene (MLG)-encapsulated nickel nanoparticles (Ni NPs) via a one-step continuous aerosol process comprising combined spray pyrolysis (SP) and thermal chemical vapor deposition (CVD). A bimodal size distribution was observed for the Ni NPs owing to droplet-to-particle and gas-to-particle conversions undergone in the SP at ~1000 °C. The number of graphene layers grown on the surface of Ni NPs in the thermal CVD was controlled by varying the reaction temperature of 300–700 °C, which perturbed the solubility and diffusion rates of carbon in Ni NPs. Finally, we demonstrated that the MLG-encapsulated Ni NP-added nanoenergetic materials were stably ignited by flash irradiation in a short ignition delay time (~267 μs) with fast burn rate (~200 m·s−1). This suggests that the MLG-encapsulated Ni NPs could play an important role as potential optical igniters for practical thermal engineering applications. Unlabelled Image • Multilayer graphene (MLG) is grown on the surface of Ni nanoparticles (NPs) in the gas phase. • The number of graphene layer is controlled by varying the reaction temperature. • MLG-encapsulated Ni NPs are ignited by flash irradiation due to photothermal effect. [ABSTRACT FROM AUTHOR]

Highlights • CNC-CMC hybrids were formed by modulating CS 2 injection flow in on/off cycles. • CNC-CMC hybrids gave rise to the stabilized-higher electrical conductivities. • Shielding effectiveness of the CNC-CMC@PU composite was enhanced. Graphical abstract Abstract Carbon nanocoil-carbon microcoil (CNC-CMC) hybrid materials were prepared via the formation of numerous carbon nanocoils (CNCs) on the surface of carbon microcoils (CMCs), using C 2 H 2 as the source gas and CS 2 as the additive gas in a thermal chemical vapor deposition system. During the reaction, CS 2 was injected into the reactor in modulated on/off cycles. The density of CNCs formed on the surface of CMCs increased with an increase in the number of on/off cycle numbers. In the as-grown state, the CNC-CMC hybrid materials showed higher electrical conductivity than that of the materials composed only of CMCs. Composites of CNC-CMC hybrid materials in polyurethane (CNC-CMC@PU) and CMCs in polyurethane (CMC@PU) were fabricated. The CNC-CMC@PU composites showed higher shielding effectiveness than the CMC@PU composites, irrespective of the mixing ratios of carbon nanomaterials in PU. Based on the shielding effectiveness and electrical conductivity, we conclude that the formation of CNC-CMC hybrid materials can enhance shielding effectiveness through a reflection-based mechanism as well as an absorption-based mechanism. [ABSTRACT FROM AUTHOR]

We report on the performance of self-powered ultraviolet (UV) photodetectors composed of SnO 2 nanowire (NW) networks. SnO 2 NWs with a length of several hundred micrometers can be synthesized by thermal chemical vapor deposition (CVD) using SnO powder as the raw material, which has the advantages of a low process temperature and no requirement for a reducing agent. Based on the characterization results obtained through synchrotron X-ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy (TEM), we determined the growth behavior of SnO 2 NWs via a vapor-liquid-solid mechanism with Au nanoparticles. The NW growth switched from an initial in-plane growth to subsequent vertical growth, forming NW cotton. This was started at a process temperature of 600 ℃ and optimized at 800 ℃. Moreover, the XRD and TEM results indicate that the NWs mainly grew in the form of SnO 2 , although the formation of SnO NWs was also possible. Metal−SnO 2 NW−metal type photodetectors were fabricated, and their photoresponsivity to UV light in the range from 200 to 400 nm was investigated. The device exhibited a photo-to-dark current ratio of ∼2.17 × 106 at an applied bias of 10 V and 254 nm UV exposure. A maximum responsivity of about 1100 A/W was estimated at a wavelength of 270 nm, and the cutoff edge wavelength appeared around 350 nm. In particular, the self-powered photoresponse at nominal zero bias was ∼1.23 nA. The results of this study support the idea that SnO 2 NWs are promising candidates for self-powered deep-UV photodetectors and that thermal CVD using SnO powder is suitable for synthesizing SnO 2 NWs at temperatures as low as 700 °C. [Display omitted] • The use of SnO powder instead of SnO 2 in thermal CVD was effective for synthesizing SnO 2 nanowires without reducing agents. • The nanowire growth switched from an initial in-plane growth to subsequent vertical growth, forming nanowire cotton. • The ultraviolet photodetector showed PDCR > 2.17 × 106, R of ∼660 A/W, and D* of ∼1.12 × 1016 Jones at a bias of 10 V. • The self-powered photoresponse at nominal zero bias was ∼1.23 nA. [ABSTRACT FROM AUTHOR]

Abstract In this study, thin films containing mono and few-layer MoS 2 were directly synthesized by one-step thermal chemical vapor deposition on Si/SiO 2 substrate. The effects of precursors' ratios including sulfur and MoO 3 powders were systematically studied by altering sulfur content for the growth of MoS 2 nanoflakes. The X-Ray diffraction patterns and scanning electron microscopy confirmed the formation of MoS 2 nanoflakes in sulfur contents of 500 and 1000 mg. According to the line width and frequency difference between the E1 2g and A 1g in Raman spectroscopy, the nanoflakes grown with sulfur content of 500 and 1000 mg were two-dimensional MoS 2 structures having few numbers of layers. Moreover, it was verified by assessment of the nanoflakes' band gap via UV–visible and photoluminescence analysis. In addition, the open-aperture and close-aperture Z -scan techniques were employed to study the nonlinear optical properties including nonlinear absorption and nonlinear refraction of the synthesized nanoflake in sulfur content of 500 mg. The experiments were performed using a diode laser with a wavelength of 532 nm as light source at different powers. The nanoflakes displayed considerable saturable absorption (SA) under low laser power and reverse saturable absorption (RSA) at higher laser powers. In general, few-layered MoS 2 would be useful for the development of nanophotonic devices like optical limiters, optical switchers, etc. [ABSTRACT FROM AUTHOR]

We fabricated tin oxide nanowires (NWs) on Au/Si 3 N 4 /Si(001) substrates using thermal chemical vapor deposition (CVD) in a hydrogen reduction atmosphere. Unlike typical thermal CVD conditions, a mixture of H 2 and Ar gas was used as the carrier gas, and a catalyst powder such as graphite was not used. The hydrogen gas maintained the reducing atmosphere and easily vaporized the SnO 2 powder without a catalyst, to supply vapors of Sn and O. This process enables vapor-liquid-solid (VLS) growth of SnO 2 NWs at temperatures below 600 °C. The formation of a eutectic AuSn alloy that acts as a liquid seed during the VLS process contributes to lowering the growth temperature. X-ray diffraction and transmission electron microscopy analysis show that SnO 2 NWs and SnO NWs coexist in the as-prepared sample. The oxygen-deficient atmosphere results in nucleation and growth of SnO NWs. [ABSTRACT FROM AUTHOR]

The synthesis of carbon-nanocoil–carbon-microcoil (CNC–CMC) hybrid materials, namely carbon nanocoils (CNCs) formed together with the growth of the carbon microcoils (CMCs), were achieved using C 2 H 2 as the source gas and SF 6 as an additive gas in a thermal chemical vapor deposition system. During the reaction, SF 6 was injected into the reactor in modulated on/off cycles. The CNC–CMC hybrid materials were not observed without the on/off cycles of SF 6 flow. When we varied the number of the on/off cycles, the density of CNCs formed in the CNC–CMC hybrid materials increased with increasing cycle number. The cause for the difference in CNC–CMC formation with cycle number was investigated. Based on the results, a growth mode of the CNC–CMC hybrid materials was proposed. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon nanotubes (N-doped CNTs) were grown on Fe-coated Si substrates through thermal chemical vapor deposition using C 2 H 2 , H 2 , Ar, and NH 3 gases. The effects of the flow rate of NH 3 gas during the growth of N-doped CNTs were investigated. As the proportion of NH 3 gas was increased from 0 to 30%, the growth rate exponentially decreased from 50 nm/s to 5 nm/s, while the diameter (10–17 nm) and wall numbers (∼7 layers) of the N-doped CNTs seldom changed. However, with the increased proportion of NH 3, the nitrogen concentration in N-doped CNTs gradually increased. From XPS and Raman results, we observed that pyrrolic and pyridine bonding was dominant at low proportions of NH 3 , causing an increase in the number of defects and disorders in the CNTs. However, the quaternary bonding appeared at the NH 3 proportions of 30%, while the concentration of pyrrolic and pyridine bonding saturated. Consequently, N-corporation inside the carbon honeycomb structure occurred above a specific proportion of NH 3. This indicates that a high proportion of NH 3 during the CNT growth is necessary to acquire the quaternary bonding between CNTs and nitrogen. [ABSTRACT FROM AUTHOR]

Carbon nanocoils (CNCs) were deposited on Al 2 O 3 substrates using C 2 H 2 and H 2 as source gases in a thermal chemical vapor deposition system. Composites of CNCs in polyurethane (CNC@PU) and CNCs plus other carbon-based materials, such as carbon microcoils (CMCs) and carbon nanotubes (CNTs), in polyurethane (CNC + CMC@PU, CNC + CNT@PU) was fabricated. The electromagnetic-wave-shielding effectiveness of the CNCs-incorporated composites were examined and compared with those of other carbon-based materials in the measurement-frequency range of 0.25–4.0 GHz. The incorporation of CNCs in CMC@PU composites reduced the shielding effectiveness; on the other hand, it slightly enhanced the shielding effectiveness of CNT@PU composites within the measurement frequency range of 0.5–3.0 GHz. Based on the resulting shielding effectiveness, we conclude that the incorporation of CNCs was useful for the materials that exhibited reflection-based shielding effectiveness although the CNCs themselves had poor electrical conductivity. [ABSTRACT FROM AUTHOR]

Stoichiometric SiC films were deposited with the commercially available single source precursor Et 3 SiH by classical thermal chemical vapor deposition (CVD) as well as plasma-enhanced CVD at low temperatures in the absence of any other reactive gases. Temperature-variable deposition studies revealed that polycrystalline films containing different SiC polytypes with a Si to carbon ratio of close to 1:1 are formed at 1000 °C in thermal CVD process and below 100 °C in the plasma-enhanced CVD process. The plasma enhanced CVD process enables the reduction of residual stress in the deposited films and offers the deposition on temperature sensitive substrates in the future. In both deposition processes the film thickness can be controlled by variation of the process parameters such as the substrate temperature and the deposition time. The resulting material films were characterized with respect to their chemical composition and their crystallinity using scanning electron microscope, energy dispersive X-ray spectroscopy (XRD), atomic force microscopy, X-ray diffraction, grazing incidence X-ray diffraction, secondary ion mass spectrometry and Raman spectroscopy. Finally, Si/SiC multilayers of up to 10 individual layers of equal thickness (about 450 nm) were deposited at 1000 °C using Et 3 SiH and SiH 4 . The resulting multilayers features amorphous SiC films alternating with Si films, which feature larger crystals up to 300 nm size as measured by transmission electron microscopy as well as by XRD. XRD features three distinct peaks for Si(111), Si(220) and Si(311). [ABSTRACT FROM AUTHOR]

In order to form nanowire (NW)-based p–n junctions, vertically-aligned ZnO–CuO hybrid NW arrays were synthesized by a two-step thermal chemical vapor deposition process. The diameter of parallel-connected ZnO and CuO NWs were estimated to be 146 ± 12 nm and 55 ± 11 nm, respectively, as observed by scanning electron microscopy. Chemical and structural characterizations of ZnO–CuO hybrid NW arrays were performed using X-ray photoelectron spectroscopy and X-ray diffraction, resulting in the formation of high-quality hexagonal ZnO and monoclinic CuO NWs. The temperature dependence of I – V curves and impedance spectra suggested that clear rectifying behavior related with thermionic emission of carriers and the presence of an electrical potential barrier between the ZnO and CuO NWs. [ABSTRACT FROM AUTHOR]

The effects of radio-frequency (rf) power on the properties of carbon thin films prepared by thermal chemical vapor deposition (CVD) enhanced with remote inductively-coupled-plasma (ICP) are investigated. Acetylene and nitrogen were used as the precursor gases, and rf-powers of ICP were set as 0, 100, 200, 300, and 400 W. The deposition temperature, working pressure, and deposition time were set as 1248 K, 4 kPa, and 2 h, respectively. The residual gases, film thicknesses, microstructures, chemical characteristics, mechanical properties, and electrical properties of carbon thin films were investigated by residual gas analyzer (RGA), field emission scanning electron microscopy, X-ray diffractometer (and Raman scattering spectrometer), X-ray photoelectron spectrometer, nanoindenter, and four point probe, respectively. RGA results reveal that the main species in the gas phase contain H 2 , C 2 H , C 2 H 2 , HCN (or C 2 H 3 ), and N 2 (or C 2 H 4 ). Moreover, C 2 H , C 2 H 2 , and C 2 H 4 can be speculated as the main species for carbon thin film deposition. As the rf-power increases from 0 to 400 W, the deposition rate of carbon thin films decreases from 204 to 36.0 nm/h. The crystallinity and ordering degree of carbon thin films increase with increasing rf-power from 0 to 400 W, but the ratio of sp 2 carbon sites in carbon thin films decreases from 95 to 75%. The Young's modulus, hardness, and electrical resistivity of carbon thin films increase with increasing rf-power. Furthermore, the effects of rf-power on the deposition rates of carbon thin films prepared by thermal CVD enhanced with remote ICP using C 2 H 2 / N 2 and CH 4 / N 2 mixtures are compared. [ABSTRACT FROM AUTHOR]

Abstract: Carbon coils were deposited on a SiO2 substrate using C2H2/H2 as the source gases and SF6 as the additive gas using a thermal chemical vapor deposition system. The formation of carbon microcoils was investigated during the deposition of the carbon coils. During the early stage of the reaction, carbon nanofilaments were formed on a specific point on the sample. Further deposition reaction increased the density of carbon nanofilaments. At this step, some of the carbon nanofilaments were observed to have a twin formation, namely, two similar shaped carbon nanofilaments attached to each other. The twin carbon nanofilaments transformed into nanosized wave-like carbon coils with increasing length. After further deposition time, the formation of double helix-type geometry of microsized carbon coils was observed, originating from the nanosized wave-like carbon coils. Based on the investigation of the point of transformation from carbon nanocoils into carbon microcoils, the detailed development of the double helix-type carbon microcoils is proposed and discussed. [Copyright &y& Elsevier]

Abstract: Carbon coated prickle-like Si particles (PS@C) are prepared by metal-assisted chemical etching and subsequent coating with an amorphous carbon film carried out by thermal chemical vapor deposition (CVD). The electrochemical characteristics of PS@C employed as anode material for lithium-ion batteries are investigated in order to find a relationship between interfacial properties and electrochemical performance. The unique morphology of prickle-like Si (PS) having empty space can accommodate volume expansion during the lithiation and delithiation. Additionally, an amorphous carbon coating layer with a thickness of 10–15nm deposited onto the PS prepared by thermal CVD is investigated as an effective way to enhance the cycle stability and rate capability of the PS electrode due to improved interfacial characteristics. The micro and nano hybrid structure of the PS material combined with the 12wt.% amorphous carbon layer plays an important role in enhancing the electrochemical performance. [Copyright &y& Elsevier]

Abstract: The properties of carbon films prepared by thermal chemical vapor deposition (thermal CVD) using camphor are investigated. As the deposition temperature increases from 1098 to 1198K, the deposition rate follows the Arrhenius law with activation energy of 59.8kJ/mol. The possible reaction paths and intermediate species of this thermal CVD process are also considered. The product gases CH 3, CH 4, and C 2 H 2 can be speculated as the main species for pyrolytic carbon deposition. The crystallinity and ordering degree of carbon films decrease with increasing the deposition temperature. Nevertheless, the sp 2 carbon sites increase with increasing the deposition temperature, and results in the decrease of electrical resistivity and the increase of water contact angle. When the camphor weight changes from 0.06 to 0.50g, the CVD reaction is controlled by a process of half order. Moreover, as the camphor weight increases from 0.30 to 0.50g, the surfaces of carbon films are partially covered with spherical particles, the water contact angle substantially increases. Finally, the results of this work are compared to those of using CH 4 and C 2 H 2 as the precursor gases. [Copyright &y& Elsevier]

Highlights: [•] Graphene was grown on Cu foil by mobile thermal chemical vapor deposition system. [•] CNT was synthesized on graphene for RuO2 nanostructure growth by thermal chemical vapor deposition system. [•] The CNT growth location was fixed through the use of photolithography technique, thereby increasing the specific area. [•] RuO2 nanostructures were coated onto CNT bundle arrays through metal organic chemical vapor deposition, in order to utilize its pseudo capacitive property. [ABSTRACT FROM AUTHOR]

Abstract: Effects of the C 2 H 2 /(C 2 H 2 + NH 3 ) ratio on the properties of thermal chemical vapor deposition (CVD) carbon films are investigated. Experimental results indicate that the deposition rate of carbon films increases with increase of the C 2 H 2 /(C 2 H 2 + NH 3 ) ratio. Ten NH 3 molecules will suppress about one C 2 H 2 molecule to form carbon films, and the deposition rate of carbon films is proportional to the partial pressure of acetylene with a power of fourth order. A model description of the kinetics of this thermal CVD process is proposed. Moreover, the ordering degree, nano-crystallite size, and the number of sp 2 carbon sites decrease with increase of the C 2 H 2 /(C 2 H 2 + NH 3 ) ratio, while the electrical resistivity increases. Few nitrogen atoms and no hydrogen are incorporated in the carbon films. When the carbon films are very thin, the carbon atoms would be uniformly deposited on a silica glass plate which results in surface smoothening. Nevertheless, when the carbon films are getting thicker, the surface roughness increases. As the C 2 H 2 /(C 2 H 2 + NH 3 ) ratio increases, the decrease of the water contact angle on a carbon film surface is mainly resulting from the decrease of the number of sp 2 carbon sites in the carbon films. The deposition temperature and working pressure of thermal CVD carbon films using the C 2 H 2 /N 2 or C 2 H 2 /NH 3 mixtures are smaller in comparison to those using a CH 4 /NH 3 mixture. Usually, when the deposition temperature is above 1073K, NH 3 is decomposed into NH 2 , which would suppress the growth of carbon films. However, as the deposition temperature is below 1073K, NH 3 serves as the dilute gas in the described processes. [Copyright &y& Elsevier]

Abstract: Carbon nanotubes (CNTs) encapsulating Fe nanowires were prepared by the chemical vapor deposition (CVD) method using ferrocene as a precursor. The influence of the addition of Pt to an Fe catalyst, which is required for growing CNTs by CVD, on the magnetic properties of the resulting CNTs was examined from the viewpoint of enhancing coercivity. Our results showed that the addition of a Pt layer on the Fe catalyst deposited on a substrate increased the coercivity of the Fe-filled CNT. This increase is due to changes in the easy magnetization axis of the Fe nanowires in the CNTs. This result indicates that the magnetic properties of the Fe-filled CNTs can be tuned by the controlling the growth conditions, which is suitable for applications in areas such as magnetic recording media and medicine. [Copyright &y& Elsevier]

Abstract: Nickel oxide (NiO) nano-structures were synthesized on random carbon nanotubes (CNTs) growing on a carbon cloth substrate processed using vacuum annealing and oxygen plasma treatment for the electric double layer capacitor electrode application (EDLC). From the electrochemical measurement analytical results the NiO nano-structure/CNT composite electrode with carbon cloth substrate exhibits low internal resistance features. The specific NiO/CNTs/carbon cloth electrode capacitance can reach up to 162.41 F/g in contrast with 53.75 F/g for the CNTs/carbon cloth electrode in 1 M KOH solution. These results indicate that NiO nano-structures formed onto CNTs/carbon cloth electrodes are suitable materials for EDLC applications. [Copyright &y& Elsevier]

Abstract: This study investigates the effects of different radio-frequency (rf) powers on the characteristics of carbon coatings on optical fibers that are prepared by thermal chemical vapor deposition (thermal CVD) enhanced with inductively coupled plasma (ICP). Methane and nitrogen were used as the precursor gases, and rf-powers of ICP were set to 0, 50, 100, 200, 300, and 400 W. The deposition temperature, working pressure, and deposition time in the thermal CVD process were set to 1248 K, 4 kPa, and 2 h, respectively. Experimental results indicate that the deposition rate of carbon coatings increases as the rf-power increases from 0 to 200 W, but decreases as the rf-power exceeds 200 W. The mean crystallite size and ordered degree of carbon coatings decrease with increasing the deposition rate. Moreover, when the rf-power increases, the carbon coatings have more sp2 carbon atoms and shift to graphite-like. With the assistance of ICP, carbon coatings can be deposited by thermal CVD at a low working pressure (about 4 kPa). Furthermore, the deposition rate and film properties can be adjusted by the rf-power. [Copyright &y& Elsevier]

Abstract: In this study, the effect of various mixture fluxes of nitrogen (N2) and hydrogen (H2) on carbon nanotube (CNT) synthesis grown on flexible carbon cloth using thermal chemical vapor deposition (thermal CVD) with ethylene (C2H4) as the carbon source and nickel (Ni) as the catalyst was investigated. Field emission scanning electron microscopy (FE-SEM) was utilized to study the morphology of CNTs on flexible carbon cloths with various N2 and H2 inlet flow rates. The results indicate that average diameter of MWCNTs decreases with increasing H2 and N2 flow rates; however, the density of CNTs increases first and then decreases with increasing H2 and N2 flow rates. On the other hand, in our field emission experiments, the result indicates that the field emission is strongly dependent on the density and geometry of MWCNTs. In addition, we also found that the contact electrical conductance measurement is an easy method to predict the field emission characteristics of MWCNTs. [Copyright &y& Elsevier]

Abstract: The advantageous crystallographic orientation of Cu surface for graphene synthesis by using thermal chemical vapor deposition (CVD) is examined by Raman mapping and electron backscatter diffraction. It is found that Cu(111) predominates over (110) and (100) for single- (SLG) or few-layer graphene (FLG) growth. To confirm this result we attempt the synthesis of graphene on Cu(111) single crystal film surfaces. We confirmed the formation of high quality and high uniformity SLG or FLG over more than 97% of the substrate surface area of 10mm×10mm by Raman mapping. [Copyright &y& Elsevier]

Abstract: This paper presents the growth evolutions in terms of the structure, growth direction and density of rapid grown carbon nanotube (CNT) forests observed by scanning and transmission electron microcopies (SEM/TEM). A thermal CVD system at around 700°C was used with a catalyst of Fe films deposited on thin alumina (Al2O3) supporting layers, a very fast raising time to the growth temperature below 25°C/s, and a carbon source gas of acetylene diluted with hydrogen and nitrogen without water vapor. Activity of Fe catalyst nanoparticles was maintained for 5min during CVD process, and it results in CNT forests with heights up to 0.6mm. SEM images suggest that the disorder in CNT alignment at the initial stage of CNTs plays a critical role in the formation of continuous CNT growth. Also, the prolonged heating process leads to increased disorder in CNT alignment that may be due to the oxidation process occurring at the Fe nanoparticles. TEM images revealed that both double- and few-walled CNTs with diameters of 5–7nm were obtained and the CNT density was controlled by thickness of Fe catalytic layer. The number of experiments at the same conditions showed a very good repeatability and reproducibility of rapid grown CNT forests. [Copyright &y& Elsevier]

Abstract: Growth of carbon nanotubes (CNTs) on bulk copper foil substrates has been achieved by sputtering a nickel thin film on Cu substrates followed by thermal chemical vapor deposition. The characteristics of the nanotubes are strongly dependent on the Ni film thickness and reaction temperature. Specifically, a correlation between the thin film nickel catalyst thickness and the CNT diameter was found. Two hydrocarbon sources investigated were methane and acetylene to determine the best conditions for growth of CNTs on copper. These results demonstrate the effectiveness of this simple method of directly integrating CNTs with highly conductive substrates for use in applications where a conductive CNT network is desirable. [Copyright &y& Elsevier]

Abstract: Electrical conductivity and a high surface area in the anode are of primary importance for the enhancement of photoelectric conversion efficiency (η) in dye-sensitized solar cells (DSSCs). This study reports on the fabrication of a DSSC anode using ZnO nanostructures. These ZnO nanostructures are coated on vertically aligned carbon nanotubes (CNTs) on stainless steel substrates using thermal chemical vapor deposition. The resulting CNTs provided a good electric connection between the ZnO overlayer and the stainless steel substrate. The photoelectric characteristics of the DSSCs were optimized with the immersion of dye for 15hrs. Compared to the η of ZnO nanostructures on randomly distributed CNTs, the η of ZnO nanostructures on vertically aligned CNTs increased approximately 4-fold. This result showed that the vertically aligned CNTs coated with ZnO nanostructures had improved the performance of DSSC. [ABSTRACT FROM AUTHOR]

Abstract: The effects of deposition parameters on characteristics of carbon coatings on optical fibers prepared by thermal chemical vapor deposition are investigated. The deposition parameters are selected as follows. The CH4/(CH4 +N2) ratio is in the range between 20% and 100%; the temperature is set from 1173 to 1248K; the working pressure is arranged between 50 and 100 kPa, and the residence time is ranging from 1.47 to 7.37s. The deposition rate, microstructure, and electrical resistivity of carbon coatings are measured. The low-temperature surface morphology of carbon-coated optical fibers is elucidated. Experimental results indicate that the deposition rate increases with increasing the CH4/(CH4 +N2) ratio, deposition temperature, working pressure, and residence time. The activation energy (= 456kJ/mol) of carbon deposition from methane was shown to correlate to the activation energy of methane dissociation. The deposition rate is proportional to about first-order of partial pressure of methane, and thus, the deposition process is mainly controlled by the process to create mono-carbon species in the carbon film. As the deposition rate increases, the size and number of particles on the carbon coating surface and electrical resistivity of carbon coatings increase, while the ordered degree, nano-crystallite size, and sp2 carbon atoms of the carbon coatings decrease. Additionally, the low-temperature surface morphology of carbon coatings shows that as the carbon coating thickness is large enough to sustain the thermal loading, decreasing the deposition rate is good for producing hermetic optical fiber coatings. [Copyright &y& Elsevier]

Abstract: The effects of C2H2/(C2H2 +N2) ratios on the characteristics of carbon coatings on optical fibers prepared by thermal chemical vapor deposition are investigated. The C2H2/(C2H2 +N2) ratios are set to 60, 70, 80, 90, and 100%. Additionally, the deposition temperature, working pressure, and mass flow rate are 1003K, 133kPa, and 40sccm, respectively. The deposition rate, microstructure, and electrical resistivity of carbon coatings are measured. The low-temperature surface morphology of carbon-coated optical fibers is elucidated. Experimental results indicate that the deposition rate increases with increasing the C2H2/(C2H2 +N2) ratio, and the deposition process is located at a surface controlled regime. As the deposition rate increases, the electrical resistivity of carbon coatings increases, while the ordered degree, nano-crystallite size, and sp2 carbon atoms of the carbon coatings decrease. Additionally, the low-temperature surface morphology of the carbon coatings shows that if the carbon coating thickness is not smaller than 289nm, decreasing the deposition rate is good for producing hermetic optical fiber coatings. [Copyright &y& Elsevier]

Abstract: To enhance the carbon nanofilaments (CNFs) formation density, SF6 was incorporated in the source gases (C2H2/H2) during the initial deposition stage. The source gases and SF6 were manipulated as the cyclic on/off modulation of C2H2/H2/SF6 flow in a thermal chemical vapor deposition system. The characteristics of the CNFs formation on the substrate were investigated according to the different cyclic modulation processes and the substrate temperatures. By the incorporation of SF6 in the cyclic process CNFs could be formed at the substrate temperature as low as 350°C. Among the different processes, mutual alternating cyclic modulation process of C2H2 and SF6 could most highly enhance the CNFs formation density. The cause for the enhancement in the characteristics of as-grown CNFs by the incorporation of SF6 was discussed in association with the slightly enhanced etching ability by the incorporation of SF6. [ABSTRACT FROM AUTHOR]

Abstract: The effect of the substrate size on the properties of carbon coatings that are deposited on the glass cylinder substrates by thermal chemical vapor deposition is investigated. Experimental results show that the deposition rate of carbon coatings decreases as the diameter of the glass cylinder increases, because the residence time of the precursor gas in the deposition zone decreases and the deposition area of the substrate increases. Experimental results also reveal that the surface roughness and electrical resistivity of carbon coatings decrease as the diameter of the glass cylinder increases, while the degree of ordering and crystallite size of the carbon coatings increase. [Copyright &y& Elsevier]

Abstract: In order to improve the field emission properties of the graphite flakes, the carbon nanotubes (CNTs) are produced on above without the metallic catalyst using mixtures of C2H2 and H2 gases by thermal chemical vapor deposition. We spin the graphite solution on the silicon wafer and dry it, then synthesize the CNTs on the graphite flakes. We change the synthetic time to obtain the optimal conditions for enhancement of field emission properties of graphite flakes. The experimental results show that the density and quality of the CNTs could be controlled significantly by the synthetic time. Besides, the field emission properties of the treated graphite flakes are also affected greatly by it. The emission current density of the treated graphite flakes reaches to 0.5mA/cm2 at 3V/μm, and the turn-on field is decreased from 7.7 to 1.9V/μm after producing the CNTs on above. [Copyright &y& Elsevier]

Abstract: SiC/SiO2 core–shell nanoparticles were firstly successfully synthesized by using a novel route of thermal CVD and thermal annealing process. The properties of the nanoparticles were characterized by scanning electron microscope, Transmission electron microscope, and X-ray diffraction. A possible growth mechanism was proposed for the nanoparticles according to the characterization results. The photoluminescence spectrum of the untreated nanoparticles revealed broad visible luminescence emission band. After the annealing treatment, the nanoparticles showed good blue emission, indicating potential applications in blue-light optoelectronic devices. [Copyright &y& Elsevier]

Abstract: High magnetic fields up to 10T are applied to thermal chemical vapor deposition (CVD) for carbon nanotube synthesis in order to control the nanotube morphology. Although changes of the nanotube morphology in the presence of magnetic field were not obviously discernible in the SEM images, an increase in the onion-like nano-carbons due to magnetic field was observed by TEM. It suggests that the magnetic field influences formation processes of nano-carbons including carbon nanotubes, via magnetic effects on metal catalysts. [Copyright &y& Elsevier]

Abstract: Patterned carbon nanotube (CNT) bundles were fabricated using thermal chemical vapor deposition (CVD) method. Patterns of different diameters and distances were defined on Si(100) substrates using photolithography. CNT bundle height was controlled using different acetylene (C2H2) flow times. The inter-bundle distance of CNTs to CNT bundle height ratio was maintained at approximately 2, a number predicted to have a maximum field emission for CNT, and left the patterned CNT bundle area as a variable parameter. The relationship between CNT bundle area and the field electron emission characteristics was studied. The lowest threshold electric field (E th) of 0.7V/μm was obtained when the total area of patterned CNT bundles was approximately 46%. The result shows that there is an optimal CNT bundle area for electron field emission. [Copyright &y& Elsevier]

Abstract: Carbon nanofibers (CNFs) mat was synthesized from Au–Pd catalyst at 700°C for 60min in 10kPa of the gas mixture of C2H2, H2 and Ar by thermal chemical vapor deposition (CVD). Fine Au–Pd catalyst as admixture on the growth substrate of SiO2 was adopted for the growth of CNFs mat. Fine Pd particles without Au particles were detected at the top/inside of as-grown CNFs by TEM-EDS analysis. The Au component within Au–Pd particles with ca. 1.5nm did not contribute to the CNF growth. On the other hand, the growth scale of individual CNF was ranged from 5 to 150nm in diameter and less than 100μm in length, by controlling H2 or Ar concentration in carbon source gas of C2H2/Ar or C2H2/H2/Ar. It seemed that Ar gas accelerated the growth of the CNFs mat and the length of each CNF was increased with increasing the supplying amount of H2. In contrast, H2 induced the lower growth density of CNFs mat and the decrease in the diameter of those. The CNFs mainly grow through adsorption and decomposition of acetylene on the surface of Au–Pd catalyst and precipitation of carbon on the surface of those. [Copyright &y& Elsevier]

Abstract: The effects of Pd addition to Fe (Pd/Fe=0, 2.5/7.5, 5/5, 7.5/2.5 and 1) and growth temperatures (920 and 970°C) on density, diameter and growth mode of carbon nanotubes (CNTs) have been studied. SEM observations and TG analyses confirmed that the CNT yields depend on Pd/Fe ratios as (7.5/2.5)>(5/5)>Pd>(2.5/7.5)>Fe at both growth temperatures. TEM data showed that addition of Pd results in tip growth mode. From Raman spectroscopy data, the order of samples’ structural quality (I G/I D ratio) are Fe>Pd/Fe (2.5/7.5)>(5/5)>(7.5/2.5)>Pd and the I G/I D ratios increase by decreasing the growth temperature. Films with higher concentration of Fe (Pd/Fe=0, 2.5/7.5) contain some single-walled carbon nanotubes. [Copyright &y& Elsevier]

Abstract: The carbon nanofibers were grown on Ni/Si and Ni/Ti/Si substrates in 1atm CH4 atmosphere at 640°C and 700°C by thermal chemical vapor deposition method. The carbon nanofibers were characterized by field emission scanning electron microscopy, transmission electron microscopy, and Raman spectrometry for morphology, microstructure, and crystallinity. The electron emission property of carbon nanofibers was also investigated by current–voltage (I–V) measurement. The results showed that the solid amorphous carbon nanofibers could be grown on Ni/Si substrate at 640°C through tip growth mechanism, the carbon nanotubes could be grown on Ni/Si substrate at 700°C through tip growth mechanism, and the carbon nanotubes could be grown on Ni/Ti/Si substrate at 700°C through root growth mechanism. [Copyright &y& Elsevier]

Abstract: The effects of deposition temperature on the properties of hermetically carbon-coated optical fibers are investigated. Hermetically carbon-coated optical fibers are prepared by thermal chemical vapor deposition using methane as the precursor gas. The deposition temperatures are 900, 925, 950, 975 and 1000 °C. The deposition rate, microstructure, electrical resistivity and Young''s modulus of the carbon films are measured. The water-repellency and low-temperature surface morphology of carbon-coated optical fibers are elucidated. The results indicate that the deposition rate and electrical resistivity of the carbon films increase with the deposition temperature, while the degree of ordering, the nano-crystallite size and the Young''s modulus of the carbon film decrease. Additionally, the water-repellency and low-temperature surface morphology of the carbon films show that the carbon film that is deposited at a temperature of 950 °C is the best for use in hermetical optical fiber coating. [Copyright &y& Elsevier]

Abstract: Carbon nanotubes (CNTs) have been grown efficiently on a Si substrate by thermal chemical vapor deposition using CH4 and CO2 gas mixtures. Fe catalytic nanoparticles were deposited on Si and carbon cloth substrates. This process is apparently different from the conventional process in gas mixtures of H2/CH4, H2/C2H2, NH3/CH4, H2/C6H6 and others. Carbon dioxide is used to replace the harmful gases of H2 and NH3 and the addition of N2 in the mixture gas of CH4 and CO2 obviously improves the growth and quality of CNTs, and allows study of the reaction growth of CNTs. This paper demonstrates the effects of compositional ratio of CH4, CO2 and N2 in the mixture gas on the growth of carbon nanotubes under atmospheric conditions. Various substrates of Si and carbon cloth were used to synthesize CNTs by using CH4–CO2–N2 gas sources. A significant difference in morphological structure was observed and analyzed on the different substrates of Si and carbon cloth. By proper adjustment of growth parameters, high quality CNTs were observed on Fe-deposited substrates. The characteristics of the as-grown carbon nanotubes on different substrates were analyzed by SEM, TEM and Raman spectroscopy. [Copyright &y& Elsevier]

Abstract: In this research, the effect of Ni, Pd and Ni–Pd catalysts have studied on morphology and structure of synthesized multi-wall carbon nanotubes (MWCNTs). Initially, thin films of Ni (with two thicknesses of 10 and 20nm), Pd/Ni (5/10nm) and Pd (10nm) were deposited as catalysts on SiO2 (60nm)/Si(100) substrates, using dc magnetron sputtering technique. The deposited films were annealed at 900°C in ammonia environment for 45min, in order to obtain nano-structured catalyst on the surface. Using scanning electron microscopy (SEM), the average size of Ni nano-islands (synthesized by the 10 and 20nm Ni films), Pd and Ni–Pd nano-islands were measured about 55, 110, 45 and 50nm, respectively. According to X-ray photoelectron spectroscopy analysis (XPS), the ratio of Ni/Pd on the surface was about 3 for the bilayer sample. The CNTs were synthesized on the nano-island catalysts at 940°C in CH4 ambient using a thermal chemical vapor deposition method. The results revealed that average diameter of the CNTs were about 70, 110, 120nm for Ni, Ni–Pd and Pd catalysts, respectively. Raman spectra of the MWCNTs showed that intensity ratio of two main peaks located in the range of 1550–1600 and 1250–1450cm−1 (as a quality factor for the CNTs) for Ni, Pd and Ni–Pd catalysts were 1.42, 0.91 and 0.85, respectively. Therefore, based on our data analysis, although addition of Pd to Ni catalyst caused a considerable reduction in the quality of the grown MWCNTs as compared to the pure Ni catalyst, but it resulted in an enhancement in the methane decomposition rate. For the pure Pd catalyst samples, both a slow methane decomposition rate as compared with Ni–Pd catalyst samples and a poor quality of CNTs were observed as compared with the Ni catalyst, under similar experimental conditions. [Copyright &y& Elsevier]

Abstract: A ZnO-covered TiO2 (denoted as ZnO/TiO2) film was prepared by incorporating a small quantity of particulate ZnO in a TiO2 matrix by thermal chemical vapor deposition. When used in a dye-sensitized solar cell, an enhancement was observed in both short-circuit photocurrent (J sc) and open-circuit voltage (V oc) by 12% and 17%, respectively, relative to those of a cell containing a bare TiO2 film. The observed J sc enhancement is attributed to the increase in the surface area of the ZnO/TiO2 film, and the V oc enhancement to the formation of a potential barrier by ZnO at TiO2/electrolyte interface. The films were characterized by FE-SEM, EDX, and XRD. [Copyright &y& Elsevier]

Abstract: We have synthesized vertically aligned carbon nanotube (CNT) emitters on iron-deposited trenches by thermal chemical vapor deposition of acetylene gas for field emission applications. The trenches patterned with various shapes and sizes were fabricated on silicon oxide/silicon substrates using a conventional lithography method and lift-off process. The vertically well-aligned carbon nanotubes were selectively grown only on iron-deposited trenches. The alignment, selectivity, and structure of carbon nanotube emitters grown on the patterned silicon trenches with various shapes and sizes are investigated. Field emission properties such as turn-on voltage and the emission current are also characterized. [Copyright &y& Elsevier]

Randomly oriented carbon nanotubes (CNTs) were synthesized directly on SiO2 substrates by thermal chemical vapor deposition (CVD) with C2H4 gas as a carbon source. To control the diameters of the carbon nanotubes, Fe–Ni thin films with different thickness from 80 to 320 nm were deposited as catalysts on SiO2 substrates by magnetron sputtering. The diameter of the resultant carbon nanotubes was dependent on the size of the catalyst particles. Moreover, a small catalyst particle permitted carbon nanotube growth. The resultant randomly oriented carbon nanotubes exhibited good field emission properties. [Copyright &y& Elsevier]

Carbon content in sputter coated iron catalyst was found to be an important parameter for the successful growth of vertically aligned carbon nanotubes on smooth silicon surfaces by means of thermal chemical vapor deposition (CVD). Pre-saturation of iron catalyst nanoparticles with carbon reduced the difference in the induction time for the growth of carbon nanotubes. This allows neighboring carbon nanotubes to support each other from its initial growth phase and thus effectively prevent them from growing into randomly oriented carbon nanotube networks on smooth silicon substrates. Cast iron containing carbon was found to be an effective sputtering target for achieving the growth of vertically aligned carbon nanotubes on smooth silicon surfaces. On the contrast, pure iron sputtering target was found to be ineffective. Correlation of in-situ measured sheet resistance of sputter coated iron catalyst with the alignment of carbon nanotubes revealed the optimal control of the amount of carbon containing iron catalyst coatings for the growth of vertically aligned carbon nanotubes on smooth silicon surfaces. The optimal catalyst coating was when the in-situ measured sheet resistance vs. sputtering time was near the transitional zone between that with rapidly declining sheet resistance and that with slow declining sheet resistance with respect to sputtering time. Co-sputtering of an iron target partially covered by graphite sheets as well as sequential sputtering of pure iron and graphite were also applied to confirm the effectiveness of carbon content in iron coatings for the growth of vertically aligned carbon nanotubes. [Copyright &y& Elsevier]

[Display omitted] • High quality thin films of MoS 2 and WS 2 were grown on p-Si using one-step thermal chemical vapor deposition. • MoS 2 /WS 2 and WS 2 /MoS 2 heterostructures were created by thermal chemical vapor deposition. • MoS 2 /p-Si as single junction showed J sc values of 0.31 µA/cm2. • MoS 2 /p-Si showed low series resistance than that of pristine WS 2 and heterostructures MoS 2 and WS 2. • Role of layer arrangement in power conversion efficiency of heterostructures is investigated. A novel structure is proposed for single heterojunction solar cells based on n-type molybdenum disulfide (MoS 2) and tungsten disulfide (WS 2) deposited on p-type silicon substrate using thermal chemical vapor deposition. Moreover, the coupled heterostructures namely MoS 2 /WS 2 and WS 2 /MoS 2 are prepared by the same method. The main aim of this study is to evaluate the photovoltaic characteristics of the proposed heterojunction solar cells. For this purpose, various characterization techniques namely X-ray diffraction, field emission scanning electron microscopy, diffuse reflectance and Raman spectroscopies are employed. XRD patterns confirm MoS 2 and WS 2 layers form in hexagonal structures. Furthermore, DRS and Raman spectroscopy confirm the formation of few layers of MoS 2 , WS 2 , MoS 2 /WS 2 and WS 2 /MoS 2 heterostructures. The greatest power conversion efficiency (PCE) is obtained for the proposed solar cell fabricated based on MoS 2 on p-type Si as single junction. This approach has suitable scientific input for application in photovoltaic cells and optoelectronic devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • BAP6-8AN20-9.5HT30-8ST30 owned nitrate adsorption capacity of 0.46 mmol/g in nitrate concentration of 200 mg/L at solution pH 3. • BAP6-8AN20-9.5HT30-8ST30 can arrive at adsorption equilibrium within 8 min, and the kinetic adsorption process was fitted by pseudo-first/second-order models. • The pore size distribution peak of BAP6 was in the larger mesoporous block (r ap / r dp = 14.1 nm/5.3 nm), while the pore size distribution peak of BAP6-8AN20-9.5HT20-8ST10 was in the smaller mesoporous block (r ap / r dp = 1.7 nm/1.9 nm). • Via continuous compound Chemical vapor deposition treatment doping N on the carbon surface, considerable N amount can be found, and mainly transformed to adsorptive site quaternary nitrogen. The mesoporous activated carbon derived from moso biomass was selected to be modified to efficiently and rapidly remove aqueous phase nitrate ions. The bamboo was activated by H 3 PO 4 and pyrolyzed at 500℃, marked as BAP6. Via various steps including thermal chemical vapor deposition (CVD), 7 types of surface modified biochar were obtained. Surface characterization of all the samples was investigated by Brunauer-Emmett-Teller method, elemental analyzer, and X-ray photoelectron spectroscopy. The quaternary nitrogen (N–Q) as strong adsorptive sites was deposited successfully on the surface of BAP6 (D avg = 6.8 nm, S BET = 1024 m2/g) by CVD doping nitrogen on it. The optimal modified mesoporous activated carbon BAP-8AN20-9.5HT30-8ST30 (D avg = 4.4 nm, S BET = 995 m2/g) owned nitrate adsorption capacity of 0.46 mmol/g in nitrate concentration of 200 mg/L at solution pH 3 and surface adsorption rate of 0.47 μmol/m2. The adsorption principle was also discussed. Adsorption kinetics were examined and analyzed by the pseudo-first-order and pseudo-second-order model. All powdery samples BAP6-8AN20-9.5HT30-8ST30 and reference samples KF-8ST10-8AN20-9.5HT30-8ST30 and HP555 were fitted by second-order model well (R2 = 0.995, 0.999 and 0.999). The results showed that BAP-8AN20-9.5HT30-8ST30 was the most rapid adsorbent to arrive at equilibrium, which took only 8 min with a Q e of 0.43 mmol/g. [ABSTRACT FROM AUTHOR]

Abstract: SiO x nanowire bunches were fabricated on a SiN x film with Au catalytic metal in the presence of an Ar flow of 50sccm at 1150°C. The resulting samples were characterized by field-emission scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. A SiN x film serves as a barrier to the diffusion of Si atoms from the Si substrate to the catalytic Au metal, where a substrate is a Si source material for SiO x nanowire (NW) growth. Using this process, we could temporally control the initial growth step of SiO x NWs and easily grow the NW bunch. [Copyright &y& Elsevier]

• The technique for making low-Z cone tip is required for fast ignition experiment. • A novel technique to make an aluminum cone tip by laser thermal chemical vapor deposition has been developed. • Trimethylaluminum (TMA) is introduced with argon gas and heated on a substrate by using a heater and a laser. • We succeeded in making desired aluminum conical shape cone tip, whose size is difficult by conventional cutting technology. We have developed a novel method to fabricate an aluminum cone tip to attach the conventional gold cone for fast ignition. An aluminum cone tip is fabricated by laser thermal chemical vapor deposition. Trimethylaluminum (TMA) is used as a chemical precursor of aluminum. TMA is introduced into a vacuum chamber with argon gas and heated on a substrate by using a heater and a laser. Aluminum products are measured by using digital zoom microscope. It is found that the deposition rate is increased with the increase of the substrate temperature, argon gas flow, and the laser intensity. However, the increase of the laser intensity increases the temperature of the deposit, and also causes the melt of the deposit. Under suitable conditions, we succeeded in making desired aluminum conical shape with 32 μm height, whose size is difficult by conventional cutting technology. Therefore, this method will be important not only to the fusion experiments but also to many other industrial applications. [ABSTRACT FROM AUTHOR]

Carbon tubule nanocoils have been synthesized at high yield by catalytic thermal decomposition of acetylene gas using iron and indium tin oxide (ITO) as the catalysts. The effect of Fe and ITO on the growth of carbon nanocoils has been investigated. By increasing the content ratio of Sn in the ITO film, the yield of carbon nanotubules may be increased but that of nanocoils is decreased. It is found that Fe-additions lead to the growth of carbon nanotubules, while ITO induces their helical growth. The yield of carbon nanocoils is determined by the elemental ratio of Sn and In. [Copyright &y& Elsevier]