Papers by Author: Xiao Ping Zou

Abstract: In this paper, the effects of position of substrates in flames, preparation time and stability of flames on carbon nanofibers are investigated in ethanol catalytic combustion. For the position of substrates, our results indicate that the temperature at the lower height (h<1cm) is too low (less that 500°C) to grow carbon nanofibers; the temperature at higher height (h>2.5cm) is suitable for the growth of carbon nanofibers, but the carbon source is insufficient because of sufficient combustion of ethanol; the optimal position of substrates in flames is more than 1cm and less than 2.5cm for massive yield because the temperature of flames is suitable for the growth of carbon nanofibers and the carbon source is also sufficient. For the preparation time, our results indicate that the optimal preparation time is more than 5min and less than 30min for massive yield. If the preparation time is excessive long (more that 30min), the deposits partly become burning in flames due to excessive products on substrates. The stability of flames has effects on the morphology and graphitization of products. Our experimental results indicate that stable flames prefer to produce noncoiled carbon nanofibers with relatively good uniformity and higher graphitization because the relatively stable flames could provide a relative stable synthesis environment.

Abstract: In this study, we report the synthesis of carbon nanotubes by floating catalytic chemical vapor deposition, which employs ferrocene as the catalyst precursors and ethanol as carbon source. We obtained massive deposits. The deposits were characterized by scanning electron microscopy, transmission electron microscopy, and visual laser Raman spectroscopy. We discussed the effects of synthesis temperature on the synthesis of carbon nanotubes by floating catalytic chemical vapor deposition. Our results indicated that the synthesis temperature could affect not only on the graphitization degree, but also on the aligned growth of carbon nanotubes and the diameter of carbon nanotubes.

Abstract: A simple direct synthesis method was used to synthesis SiC/SiO2 core–shell coaxial nanocables by thermal evaporation of the mixture powders of silicon monoxide and active carbon at 1300°C and condensation on Si substrate without assistance of any catalyst. The SiC core typically has diameters of 10-40 nm and is covered by a uniform layer of 2-10nm thick amorphous SiO2. A double vapor–solid growth process is proposed for the formation of this novel structures based on detailed structural characterizations. The cable nanostructures may find applications as building blocks in nanomechanical or nanoelectronic devices.

Abstract: The synthesis of lead hydroxide nanowires by solution-phase chemical reactions of lead nitrate with alkali by adding sodium chloride was reported. The obtained lead hydroxide nanowires have a length of a few micrometers and a diameter of about several tens of nanometers. The selected-area electron diffraction reveals that these lead hydroxide nanowires are single crystalline. Controlled experiments indicate that lead hydroxide nanowires prefer to form at higher concentration of chloride ions in lead nitrate precursor solutions, such as Cl- : Pb2+ = 5:1 and 6:1.

Abstract: ZnO micro/nano rods were grown　on fluorine doped tin oxide (FTO) substrates by aqueous chemical growth (ACG) using Zn(NO3)2•6H2O and C6H12N4 at low temperature. For comparison, the yield of nanorods on indium-tin-oxide (ITO) substrates with same parameters was also discussed. SEM, TEM, SAED and XRD were utilized to characterize morphologies and structures of ZnO crystals. It was indicated that the temperature and the concentration of the solution significantly leads to the yields of the ZnO. Single-crystalline ZnO micro/nano rods could be synthesized via an aqueous solution route without adding alkali solution at 70°C in large area.

Abstract: In this paper, we report the synthesis of Fe-filled carbon nanotube arrays by floating catalyst chemical vapor deposition, which employed ferrocene as both catalyst precursor for carbon nanotube growth and the iron source for iron filling. We obtained Fe-filled carbon nanotube arrays perpendicular to the surface of the quartz substrates by floating catalyst chemical vapor deposition. We also conducted controlled experiments at different temperatures. Our results indicated that a higher synthesis temperature is needed for synthesizing Fe-filled carbon nanotube arrays. Magnetic property measurements revealed that the Fe-filled carbon nanotubes exhibited a high average coercivity of about 589.97G.

Abstract: KCl is usually used as the supporting electrolyte in electrochemical deposition of Zinc oxide materials. Besides the role of supporting electrolyte, it can also influence the morphology of the fabricated materials. In this work, ZnO and zinc hydroxide chloride hydrate (Zn5(OH)8Cl2•H2O) mixture with platelet-like morphology were electrochemically deposited directly on ITO-coated glass substrates at 65°C. The electrolyte was 0.1M Zn(NO3)2•6H2O with KCl concentration varied from 0 to 3.2M. It was found that only ZnO thin film was obtained when the concentration of KCl was below 0.02M. Plates structure appeared as the concentration of KCl increased to 0.04M. Plentiful plates were obtained when the concentration of KCl was 0.05M-0.2M. From the X-ray diffraction, it was confirmed that the plate films was the mixture of ZnO and Zn5(OH)8Cl2•H2O. The plates showed perfect single crystal structure confirmed by selected area electron diffraction. Zn and Zn5(OH)8Cl2•H2O were obtained when the concentration of KCl was above 0.8M.

Abstract: In this paper, zinc oxide nanorods were prepared on many different substrates in the aqueous solution without adding alkali solution at 60°C. A layer of ZnO particles as the seeds for the growth were not needed to be coated on the substrates beforehand. A higher uniform and denser packed array of hexagonal ZnO nanorods forms on the glass substrate than that on the other substrates in our experiments. This technique is applicable for the preparation and patterning of functional ZnO films at low temperature. The growth mechanisms of the as-synthesized ZnO nanorods were also proposed.

Abstract: Arrays of zinc oxide (ZnO) micro/nano pillars have been synthesized on indium-tin-oxide (ITO) substrates by a solution route under an external electric current. They were pillar-like morphologies and grew along the c-axis. Some comparative experiments showed that applying the external electric current effectively improved the alignment of the product in a short time. It was indicated that the micro/nano pillars can be obtained in a short time under an external electric current.

Abstract: In this paper, we developed a simple and effective method to fabricate lead oxide plate films by electrochemical deposition. The electrolyte was lead nitrate aqueous solution with or without Cl- ions. Stainless steel plate was employed as both cathode and substrate, and a graphite plate as anode. We found the optimal current density of synthesizing lead oxide plate films is 10-25mA/cm2 when there were no Cl- ions in the electrolyte. If equal Cl- ions were added in lead nitrate aqueous solution, the optimal current density of synthesizing lead oxide plate films is less than 10mA/cm2. The as-prepared lead oxide plate films have orthorhombic crystals structure.