Xiang Min Meng

ZnO Nanorod Arrays and Nanowires by Hydrothermal Growth

We are reporting here on an inexpensive and facile fabrication method for ZnO nanorod arrays by hydrothermal growth at low temperature (90°C). In our experiment, ZnO nanostructures were grown on glass substrate using an equimolar (0.1M) aqueous solution of Zn(NO3)2•6H2O (zinc nitrate hexahydrate) and C6H12N4 (HMTA) as precursors solution, and using ammonia solution to controlling the pH levels. It enable easily obtained arrayed ZnO nanorods on substrate, and nanowires which grown on nanorod arrays were identified after about 1 month in the air. The growth process of nanorods and the formation mechanism of nanowires were investigated.

Influence of Potassium Chloride on the Electrochemical Deposition of ZnO Plate Films

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.

Large-Scale Synthesize ZnO Micro/Nano Rods Fabricated from Aqueous Solutions at Low Temperature

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.

2-D ZnO Nanostructures on Aluminum by Solution Method

Two-dimensional ZnO nanostructures with various morphologies were synthesized on aluminum by solution method at 90°C. In our experiment, 0.1M zinc chloride (ZnCl2) was used as a ZnO precursor, and different volume of ammonia solution (25％) was added to the solution. We characterize the morphology and nanostructure of 2-D ZnO nanostructures and study the growth mechanisms of these 2-D structures. It should be noted that the existence of Cl﹣ plays an important role on the formation of 2-D structures.

Lead Hydroxide Nanowires Obtained from Lead Nitrate Solution by Adding Chloride Ions

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.

ZnO Porous Plate Films Application in Quantum Dot Sensitized Solar Cells

As a kind of semiconducting and promising material, ZnO has been extensively used in dye-sensitized solar cells (DSSCs). Quantum dot sensitized solar cells (QDSSCs) has more potential to increase the efficiency of solar cells compared with DSSCs. Here we developed a simple and effective way to fabricate ZnO porous plate films by electrochemical deposition and anneal in air on ITO-coated glass substrates. CdS quantum dots were attached to the surface of the porous plate films by chemical bath deposition technique. Quantum dot-sensitized ZnO porous plate films solar cells exhibited short-circuit current ranging from 0.22-0.57mA/cm2 and open-circuit voltage of 0.42 -0.57V when illuminated with 100 mW/cm2 simulated AM 1.5 G irradiation.

Research on the Process of Liquid Droplet Impinging on the Liquid Film

The impacting of liquid droplet on the liquid film appears in many engineering processes. In the fusion reactor, liquid metal is used as the heat transfer media, moderator and breeder in the condition of high heat flux. The paper analyzes the flow behavior of liquid droplet impinging on the liquid film from the aspects of experiment research. In the impinging, splashing means the production of secondary drop coming from the cusp of the crown flow or Worthington jet. Impinging velocity, liquid film thickness, droplet diameter, fluid properties and impinging angle have been analyzed separately.

Electrochemical Deposition of Metallic Lead Particle Film

The preparation of metallic lead films by electrochemical deposition was reported. Although primary deposits at fresh state (also referred to as fresh deposits) were indeed metallic lead films, the fresh lead films could be rapidly oxidized to lead oxide in air. To obtain long stable metallic lead films, the key process is how to prevent the oxidization of fresh lead films. Our studies indicate that the washing of fresh metallic lead films in absolute alcohol is a simple but effective method to protect the lead films from the oxidization for an extended period of more than 20 days.

Electrochemical Deposition of Lead Oxide Nanorods

Synthesis of PbO nanorods on an ITO glass by electrochemical deposition was reported. Compared with previous report on the electrochemical deposition of PbO nanorods on stainless steel substrates, massive PbO nanorods were obtained with good reproducibility. The PbO nanorods have a length of several tens of micrometers and a diameter of about 100-200nm. The process for electrochemical deposition of PbO nanorods on ITO glass was investigated.

Growth of Arrayed ZnO Nanorods from Aqueous Solution at 60°C

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.