乙醇做碳源Mo-Co/MgO做催化剂合成单壁碳纳米管

本文采用柠檬酸法制备Mo-Co/MgO催化剂, 在小型流化床中, 以Ar气为载气直接携带乙醇蒸汽进入反应器, 通过化学气相沉积（CCVD）技术来合成制备单壁碳纳米管（SWCNTs）。利用扫描电镜和拉曼光谱方法研究了催化剂组分比例和载气流量等对SWCNTs制备的影响。研究结果表明: 以乙醇做碳源, Mo1-Co10/MgO做催化剂, Ar气流量为150sccm时制备的单壁碳纳米管质量最佳。     

Fabrication of multiwalled carbon nanotubes in the channels of iron loaded three dimensional mesoporous material by catalytic chemical vapour deposition technique

The growth of multiwalled carbon nanotubes (MWNTs) was successfully achieved in the channels of three dimensional (3D) iron loaded mesoporous matrices (KIT-6) by employing catalytic chemical vapour deposition (CCVD) technique. The synthesised MWNTs, which were characterised by SEM, TEM and Raman spectroscopy, consist of thick graphene layers of about 10 nm composed of 29 graphene sheets with inner and outer diameter of ∼17 nm and ∼37 nm, respectively. The Raman spectrum showed the formation of well-graphitised MWNTs with significantly higher I_G/I_D ratio of 1.47 compared to commercial MWNTs. Comparatively, 2 wt% Fe loaded KIT-6 material produced a better yield of 91%, which is also highest compared with the report of MWNTs synthesis using mesoporous materials reported so far.     

High oxygen vacancy tin oxide synthesized by combustion chemical vapor deposition (CCVD)

Tin oxide nanotentacles were synthesized by combustion chemical vapor deposition in air. Their surface composition and optical properties were then investigated using X‐ray photoelectron spectroscopy (XPS) and Raman spectroscopy. XPS core level spectra indicate that these nanotentacles are of high oxygen vacancy with chemical composition of about SnO_1.6, which is also supported by the Sn Auger parameter. Besides SnO₂, the optical properties of SnO were detected in Raman spectrum. Moreover, two new Raman peaks were found for the SnO₂ phase because of the high oxygen vacancy concentration. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis and characterization of nanocarbon having different morphological structures by chemical vapor deposition over Fe-Ni-Co-Mo/MgO catalyst

Catalytic chemical vapor deposition (CCVD) is one of the most promising synthesis methods for economically producing large quantities of different nanocarbon structures. Here we report a systematic study of the synthesis conditions for the preparation of different nanocarbon morphological structures via acetylene decomposition over the surface of quaternary-metallic catalyst (Fe-Ni-Co-Mo) supported on MgO (Fe-Ni-Co-Mo/MgO). In particular, the effect of temperature, and the reaction time were investigated to optimize the yield, quality, size and graphitic crystallinity of the deposited carbon. The study showed a successful synthesis of: (i) a high-yield and quality bamboo-like multiwalled carbon nanotubes (b-CNT), (ii) hybrid graphene/carbon nanotubes (G/CNT), and (iii) multilayer graphene (MLG). The structures of the obtained products were characterized by HR-TEM, TGA, Raman spectroscopy, FTIR and X-ray diffraction. The results found seem essential for realizing the role of different synthesis parameters on the yield, quality, and morphology of the synthesized product.     

High-temperature oxidation behavior of SiO2 protective layer deposited on IN738LC superalloy by combustion CVD (CCVD)

A SiO₂ protective coating was deposited on an IN738LC alloy using CCVD. The physical properties of a SiO₂ protective layer are influenced by the amount of tetraethyl orthosilicate (TEOS, C₈H₂₀O₄Si). Therefore, the SiO₂ protective coating was deposited using different TEOS concentrations and deposition times to optimize the conditions. The deposited coating layer was confirmed to be a SiO₂ layer by SEM, EDX, and ESCA analyses. The oxidation resistance of the alloy was evaluated by thermo gravimetric analysis. The oxidation resistance of the SiO₂ protective coating was highest when the coating was processed at a TEOS concentration of 0.05 mol/l, which is the highest concentration of source material used. The surface roughness of the SiO₂ protective layer also increased with increasing TEOS concentration. The surface roughness of the coating had little effect on the oxidation resistance for a film thickness of approximately 1 μm.     

Ni-Fe/4A分子筛催化剂可控制备大内径碳纳米管

以乙醇为碳源,Ni-Fe/4A分子筛为催化剂,采用化学气相沉积法制备大内径碳纳米管(LIDCNTs)。研究了Ni/Fe的物质的量比(n_Ni∶n_Fe)、碳纳米管(CNTs)的制备温度、催化剂的煅烧温度和4A分子筛载体对CNTs内径的影响。采用TEM、SEM、XRD和BET对LIDCNTs和还原后的催化剂进行了分析。结果显示,LIDCNTs的内径随着CNTs的制备温度、催化剂的煅烧温度的升高和n_Ni∶<     

Electronic, chemical and structural characterization of CNTs grown by acetylene decomposition over MgO supported Fe-Co bimetallic catalysts

The electronic and chemical structure of carbon nanotubes synthesized by decomposition of acetylene over Fe-Co bimetallic catalysts in different growth conditions, were analyzed by valence band photoelectron spectroscopy and scanning electron microscopy. A clear relationship between the bonding features and the growth condition allowed us to determine the key parameters in terms of temperature, growth time and catalyst content. Furthermore, the analysis allowed a determination of the byproducts.     

水滑石基催化剂催化合成碳纳米材料的研究进展

碳纳米材料是一类推动能源存储、 多相催化、 高性能复合和生物医药等领域发展的重要材料, 可控合成碳纳米材料对相关领域的发展具有重要意义. 水滑石(LDHs)材料具有层板金属种类及含量可调等特点, 经焙烧、 还原后可制备出金属种类、 密度和粒径分布各异的高分散、 高稳定金属纳米催化剂, 可实现高效催化生长各种类型的碳纳米材料. 此外, 通过调控反应条件和反应器等, 可以影响LDHs基金属纳米催化剂催化生长的碳纳米材料的结构和性能. 本文总结了LDHs基金属纳米催化剂的可控制备、 碳纳米材料结构调控以及利用LDHs基催化剂制备的碳纳米材料的应用等方面的研究工作, 并阐明了催化剂的可控制备是控制合成碳纳米材料的核心手段, 这为利用LDHs基催化剂进一步合成更高性能碳纳米材料的研究指明了方向. 此外, 本文还结合近些年在光、 电及光热催化方面的研究进展, 展望了基于新型LDHs纳米结构生长碳纳米材料的研究前景.