Gang Qiang Yang

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.

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.

Affection of Post-Nitrogen-Doping of ZnO Columnar Films Photo-Anode on Performance of Dye-Sensitized Solar Cells

ZnO was a promising n-type conductive semiconductor material for dye-sensitized solar cells. Stable and efficient preparation of high quality p-type ZnO films became the main difficulty in current research. In this paper, a nitrogen-doped ZnO columnar film on an indium tin oxide (ITO) substrate was successfully obtained by gas phase method. The absorption of visible light was improved by nitrogen-doped ZnO columnar films. This experiment provided a good strategy for the full utilization of solar energy.

Application of ZnO Nanostructure by Hydrothermal Growth in Quantum Dot Sensitized Solar Cells

In this paper, we mainly talk about two kinds of ZnO nanostructure materials which are rod and flower structure by hydrothermal growth as photoanode of quantum dot sensitized solar cells (QDSSCs). Using chemical bath deposition to assemble CdS quantum dots onto ZnO nanostructure materials, and after different CBD cycles we could get the cell parameters of different CBD cycles respectively in their I-V curves, from which we could see it is the flower structure that has the highest efficiency which is 0.346% after 9 CBD cycles and the short-circuit current is 2.88 mA/cm2. Therefore, we could see that ZnO flower structure has a potential application in solar cell devices as the photoelectrode to gain higher photoelectric conversion efficiency (PCE).

Influence of Precursor Solution Concentration on Zinc Oxide Nanostructures by Hydrothermal Growth

In this paper, various ZnO nanostructures, such as rods, flowers were grown on indium-tin-oxide (ITO) substrates by hydrothermal growth at low temperature, using the different concentrations of equimolar (1:1) zinc nitrate (Zn (NO3)26H2O) and methenamine (C6H12N4) mixed as precursors solution, and adding ammonia solution to control the pH levels. SEM, XRD were utilized to characterize morphologies and crystal structures of ZnO. It was indicated that the concentration of precursor solution leads to the significantly changes in the nanostructured ZnO. The possible growth mechanism is discussed in this work.

Hierarchical ZnO Nanostructure on Steel Substrate by Electrochemical Deposition

In this paper we use electrochemical deposition to grow a layer of gray compact film on the steel, characterized the product by X-ray diffraction (XRD) we find the ZnO cone-like rods and hierarchical rod-like nanostructure are all preferentially growing along the C-axis, which is confirmed by the direction of crystal growth in the transmission electron microscope (TEM) image. In the TEM image we find the hierarchical ZnO nanorods have an in situ growth in the high-energy electron beam irradiation, which makes the specific surface area increase and to some extent enhance the absorption of light energy.

Influence of Ammonia Solution on Zinc Oxide Nanostructures by Hydrothermal Growth

In previous work, ZnO nanorods and nanoflowers were synthesized on indium-tin-oxide (ITO) substrates by hydrothermal growth at low temperature ,using the different concentrations of equimolar (1:1) zinc nitrate Zn (NO3)26H2O and methenamine (C6H12N4) mixed as precursors solution, and adding ammonia solution to control the pH levels. In this paper, for comparison, the same experiment without ammonia solution was also discussed. SEM, XRD were utilized to characterize morphologies and crystal structures of ZnO. It was indicated that the pH of precursor solution leads to the significantly changes in the nanostructured ZnO. Besides, a hierarchical structure of some of the micro/nanotubes was obtained .The possible growth mechanism is discussed in this work.