Preparation and Photoactive Characterization of Tube-shaped Al-doped ZnO Ceramics.
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Preparation and Photoactive Characterization of Tube-shaped Al-doped ZnO Ceramics. Yoshinobu FUJISHIRO, M.AWANO, and S.KANZAKI Synergy Materials Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Joint Research Center for Advanced Technology, Shidami Human Science Park 2268-1, Shimo-shidami, Moriyama-ku, Nagoya, 463-8687, JAPAN. E-mail : [email protected] ABSTRUCT Tubular Al-doped ZnO particles were prepared by homogeneous precipitation in the mixed solutions of Al(NO3)2, Zn(NO3)2, sodium dodecyl sulfate (SDS) surfactant and urea. At the molar ratio of Metal ions(Mt) : SDS : urea : H2O is 1 : 2 : 20 : 60, tubular products formed by heating at 80°C for 12 h. Plate like ZnO particles were obtained at Mt : SDS : urea : H2O = 1 : 2 : 10 : 60 or 1 : 1 : 20 : 60. The diameter of typical ZnO tube is ca.100 nm, and the length of tube is about 600nm (aspect ratio = 6). The relative surface area of tubular Al-doped ZnO is ca. 40.2 m2/g. The photo-decomposition rate of NO3- ions using tubular Al-doped ZnO particles was higher than standard TiO2 photo-catalysts (P-25) by irradiation >290nm light in 10mM KNO3-10vol%EtOH solutions at 30°C. The obtained materials showed DC conductive properties as compacted substrate by sintered at 400°C. INTRODUCTION Porous particles including meso- and nano- scale pores are focus to molecular sieve, catalysis, chemical recovery, selective chemical reaction space and nanocomposite material because of space effects on the high efficiency for chemical reactions such as purification and synthesis of selective products1-4. Furthermore, the ordered space materials such as carbon nanotube, MCM-41 mesoporous silicate and non-carbon nanotube (SiO2, Al2O3, TiO2, V2O5, MoO3 SnO2 and Co3O4 etc.) are developing as nano- technology materials5-12. 1D-tubular semiconductor particles are expecting for the application in microelectrodevices, for example, electrode, electrochemical catalysis, sensor and energy
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conversion unit such as dye-sensitized solar cell etc12. On the other hand, photo-catalysis consisting of meso- and nano- pore is recently important for purification process of solvable organic and inorganic pollutants in industrial drains such as amine or NO3- etc because of high surface area of nano-porous particles. Al-doped ZnO is well known photoelectro conversion materials such as solar cell or cathode luminescence of green light, which is n-type direct band-gap (Eg~3.37eV) semiconductor. Recently, new applications of Al-doped ZnO are also reported for electro-devices, which are thermoelectrical and cathode luminescence materials by reducing electro resistance due to control of doping concentration such as Al ions13,14. Synthesis of the tubular particles has been developing by gas reaction such as CVD and laser abrasion techniques5. Disadvantages of gas reaction are low product yield and high system cost. On the other hand, solution process such as co-precipitation is easy process and large products yields. Solution synthesis of mesoporous m
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