One-step in situ synthesis and characterization of W18O49@carbon coaxial nanocables

2009 ◽  
Vol 24 (5) ◽  
pp. 1833-1841 ◽  
Author(s):  
Yuqin Zhou ◽  
Yong Zhang ◽  
Ruying Li ◽  
Mei Cai ◽  
Xueliang Sun
Keyword(s):  
Raw Materials ◽  
Tungsten Powder ◽  
Carbon Sources ◽  
Chemical Vapor ◽  
Deposition Process ◽  
In Situ Synthesis ◽  
X Ray ◽  
Coaxial Nanocables ◽  
Catalyst Systems

We demonstrate here in situ synthesis of bulk yield W18O49@carbon coaxial nanocables based on an easily controlled chemical vapor deposition process at relatively low temperature (760 °C) using metallic tungsten powder and ethylene (C2H4) as the raw materials. Transmission electron microscope (TEM), energy dispersive x-ray (EDX), and x-ray diffraction (XRD) analyses indicate that the resultant nanostructures are composed of single-crystalline W18O49 nanowires, coaxially covered with amorphous carbon walls. A vapor–solid (VS) mechanism is proposed to interpret the formation of the nanocables. The effect of carbon sources on the nanocable growth was investigated. The results revealed that the introduction of carbon species not only causes the production of W18O49@C nanocable structures, but also obviously modulates growth behaviors and core/shell diameter ratio of the nanocables. The obtained nanocables may find great applications in catalyst systems and optical and electronic nanodevices because of their enhanced surface properties, as well as in high chemical stability.

scholarly journals Changing Contents of Carbon Hybridizations in Amorphous Hydrogenated Carbon Layers (a-C:H) on Sustainable Polyhydroxybutyrate (PHB) Exhibit a Significant Deterioration in Stability, Depending on Thickness

2019 ◽  
Vol 5 (3) ◽  
pp. 52 ◽  
Author(s):  
Torben Schlebrowski ◽  
Lucas Beucher ◽  
Hadi Bazzi ◽  
Barbara Hahn ◽  
Stefan Wehner ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Raw Materials ◽  
Chemical Vapor ◽  
Drift Spectroscopy ◽  
Significant Deterioration ◽  
X Ray ◽  
Diffuse Reflectance Infrared ◽  
X Ray Absorption ◽  
Amorphous Hydrogenated Carbon

PHB is a biodegradable polymer based on renewable raw materials that could replace synthetic polymers in many applications. A big advantage is the resulting reduction of the waste problem, as well as the conservation of fossil resources. To arrange it for various applications, the surface is arranged by plasma-enhanced chemical vapor deposition (PECVD) with amorphous hydrogenated carbon layers (a-C:H). Here, on a 50 µm thick PHB-foil, a-C:H layers of different thicknesses (0–500 nm) were deposited in 50 nm steps. Surface topography was investigated by scanning electron microscopy (SEM), chemical composition by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and wettability checked by contact angle. In addition, layers were examined by synchrotron supported X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS), which revealed thickness dependent changes of the sp2/sp3 ratio. With increasing thickness, even the topography changes show internal, stress-induced phenomena. The results obtained provide a more detailed understanding of the predominantly inorganic a-C:H coatings on (bio)polymers via in situ growth.

scholarly journals In situ synthesis of multi-walled carbon nanorings by catalytic chemical vapor deposition process

2019 ◽  
Vol 9 (2) ◽  
pp. 119-126 ◽  
Author(s):  
Sivamaran Venkatesan ◽  
Balasubramanian Visvalingam ◽  
Gopalakrishnan Mannathusamy ◽  
Viswabaskaran Viswanathan ◽  
A. Gourav Rao
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Deposition Process ◽  
In Situ Synthesis ◽  
Chemical Vapor Deposition Process ◽  
Catalytic Chemical Vapor Deposition ◽  
Carbon Nanorings ◽  
Vapor Deposition Process

A green in situ synthesis of silver nanoparticles on cotton fabrics using Aloe vera leaf extraction for durable ultraviolet protection and antibacterial activity

2016 ◽  
Vol 87 (19) ◽  
pp. 2407-2419 ◽  
Author(s):  
Qingqing Zhou ◽  
Jingchun Lv ◽  
Yu Ren ◽  
Jiayi Chen ◽  
Dawei Gao ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Aloe Vera ◽  
Cotton Fabrics ◽  
In Situ Synthesis ◽  
Uv Protection ◽  
X Ray ◽  
Jcpds File ◽  
Laundering Durability

This study presented a simple and environmentally friendly method of in situ synthesis of silver nanoparticles (AgNPs) on cotton fabrics for durable ultraviolet (UV) protection and antibacterial activity using Aloe vera leaf extraction (AVE) as a reducing and stabilizing agent. Cotton fabrics were pretreated in water, and then immersed in AgNO3 and AVE, respectively. Cotton fabrics were characterized by small angle X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis, UV protection, antibacterial activity, and laundering durability. Comparing with the smooth surface of the control cotton fabric, SEM and energy dispersive X-ray spectrometry (EDX) results showed that there were a considerable number of Ag2O and AgNPs loading on the surface of the pretreated and Ag loaded cotton fabrics. The XRD pattern indicated, respectively, the existence of Ag2O and AgNPs, the structures of which were similar to JCPDS File No.65-3289 and JCPDS File No. 01-071-4613 on the pretreated and Ag loaded cotton fabrics. The pretreated and Ag loaded cotton fabrics showed excellent UV protection, antibacterial activity, and laundering durability, especially the Ag loaded cotton fabric, of which the UV protection factor value and transmission of UVA were 148 and 1.11%, respectively, after 20 washing cycles, and the clear zone width was more than 4 mm against E. coli or S. aureus. AgNPs facilitated the improvement of the thermal property of the cotton fabrics. Thus this facile in situ reduction of AgNPs with AVE may bring a promising and green strategy to produce functional textiles.

scholarly journals Carbon-Involved Near-Surface Evolution of Cobalt Catalyst during Reaction: An in-situ Study

2020 ◽  
Author(s):  
Feng Yang ◽  
Haofei Zhao ◽  
Wu Wang ◽  
Qidong Liu ◽  
Xu Liu ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Carbon Diffusion ◽  
Deposition Process ◽  
Catalytic Performance ◽  
Surface Evolution ◽  
Near Surface ◽  
Co Catalysts ◽  
Transmission Electron ◽  
Walled Carbon Nanotubes

Abstract When carbon-containing species are involved in reactions catalyzed by transition metals at high temperature, the diffusion of carbon on/in catalysts dramatically influence the catalytic performance. Acquiring information on the carbon-diffusion-involved evolution of catalysts at atomic level is crucial for understanding the reaction mechanism yet also challenging. For the chemical vapor deposition process of single-walled carbon nanotubes (SWCNTs), we developed methodologies to record in-situ the near-surface structural and chemical evolution of Co catalysts with carbon permeation using an aberration-corrected environmental transmission electron microscope and the synchrotron X-ray absorption spectroscopy. The nucleation and growth of SWCNTs were linked with the partial carbonization of catalysts and the alternating dissolvement-precipitation of carbon in catalysts. The dynamics of carbon atoms in catalysts brings deeper insight into the growth mechanism of SWCNTs and also sheds light on inferring mechanisms of more reactions. The methodologies developed here will find broad applications in studying catalytic and other processes.

Structural Defects of Silicon Epitaxy and Epi/Substrate Interface Related to Improper In-Situ Surface Cleaning at Low Temperatures

1990 ◽  
Vol 202 ◽  
Author(s):  
Tri-Rung Yew ◽  
Rafael Reif
Keyword(s):  
Defect Formation ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Surface Cleaning ◽  
Structural Defects ◽  
Plasma Cleaning ◽  
Substrate Interface ◽  
Silicon Epitaxy ◽  
Pressure Chemical

ABSTRACTThis paper investigates the defect formation at the epi/substrate interface and epitaxial layers due to an improper in–situ Ar or Ar/H2 plasma cleaning at 500–800 °C Deposition process was carried out immediately after the in–situ cleaning process by ultralow pressure chemical vapor deposition process (ULPCVD) from SiH4/H2. Characteristics of the defects and their relationship with damage or impurity contaminations at the interface are presented. Finally, an optimum cleaning condition which ensures high quality epitaxial growth is addressed.

scholarly journals Highly Visible Photoluminescence from Ta-Doped Structures of ZnO Films Grown by HFCVD

Crystals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 395 ◽  
Author(s):  
Víctor Herrera ◽  
Tomás Díaz-Becerril ◽  
Eric Reyes-Cervantes ◽  
Godofredo García-Salgado ◽  
Reina Galeazzi ◽  
...  
Keyword(s):  
Raw Materials ◽  
Chemical Vapor ◽  
Growth Direction ◽  
Hexagonal Structure ◽  
Zno Films ◽  
Sem Images ◽  
Wurtzite Phase ◽  
Fixed Amount ◽  
X Ray ◽  
Doped Zno

Tantalum-doped ZnO structures (ZnO:Ta) were synthesized, and some of their characteristics were studied. ZnO material was deposited on silicon substrates by using a hot filament chemical vapor deposition (HFCVD) reactor. The raw materials were a pellet made of a mixture of ZnO and Ta2O5 powders, and molecular hydrogen was used as a reactant gas. The percentage of tantalum varied from 0 to 500 mg by varying the percentages of tantalum oxide in the mixture of the pellet source, by holding a fixed amount of 500 mg of ZnO in all experiments. X-ray diffractograms confirmed the presence of zinc oxide in the wurtzite phase, and metallic zinc with a hexagonal structure, and no other phase was detected. Displacements to lower angles of reflection peaks, compared with those from samples without doping, were interpreted as the inclusion of the Ta atoms in the matrix of the ZnO. This fact was confirmed by energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD) measurements. From scanning electron microscopy (SEM) images from undoped samples, mostly micro-sized semi-spherical structures were seen, while doped samples displayed a trend to grow as nanocrystalline rods. The presence of tantalum during the synthesis affected the growth direction. Green photoluminescence was observed by the naked eye when Ta-doped samples were illuminated by ultraviolet radiation and confirmed by photoluminescence (PL) spectra. The PL intensity on the Ta-doped ZnO increased from those undoped samples up to eight times.

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