Anodically Fabricated Sr-doped TiO2 Nanotube Arrays for Photoelectrochemical Water Splitting Applications
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Anodically Fabricated Sr-doped TiO2 Nanotube Arrays for Photoelectrochemical Water Splitting Applications Hoda A. Hamedani,1 Nageh K. Allam,2 Hamid Garmestani 1, Mostafa A. El-Sayed2 1 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, U.S.A. 2 Laser Dynamics Laboratory, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, U.S.A. ABSTRACT The present work reports the synthesis of self-organized strontium-doped titania nanotubes arrays as a potential material for photocatalytic water splitting. Electrochemical anodization process was used to grow such material under various electrochemical conditions. The effect of dopant concentration on the morphology and photoelectrochemical properties of the material was investigated. The microstructure, morphology and composition of as-prepared and heat treated nanotubes were characterized by field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS). The results showed that increasing the dopant concentration up to its solubility limit results in higher photoelectrochemical activity. A preliminary proof of concept of the photocatalytic activity of the fabricated material was estimated in terms of the use of such material as a photoanode for photoelectrochemical water splitting. INTRODUCTION Photoelectrochemical water splitting has received great attention as an attractive way of hydrogen production from natural and renewable resources. Extensive research have focused on the development of semiconductor photocatalysts that have proper band gap (> 1.23 eV) and desirable relative energetic positions of the conduction and valence bands for water dissociation into hydrogen and oxygen. A wide range of transition metals such as Fe, Mo, Mg, Ag, Pt, Co, Cr, Mn and non-metal elements such as C, N, B, F have been used as dopants for the enhancement of the photoelectrochemical properties of TiO2, which is the most promising photoelectrode material due to its low cost, nontoxicity, and photostability1-5. Recently, strontium titanate (SrTiO3) has been intensively investigated as a photoanode for water splitting due to its high corrosion resistance, excellent photocatalytic activity, high stability, and non-toxicity. Fabrication of SrTiO3 from amorphous TiO2 nanotubes arrays have been performed using hydrothermal process that resulted in the formation of TiO2/SrTiO3 composites with improvement in the overall photoelectrochemical performance6-8. In this work, in-situ doping of TiO2 nanotubes with strontium is investigated.
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EXPERIIMENT The T polished titanium foiil (0.25 mm thick, t Alfa A Aesar) was rrinsed in an uultrasonic baath of ethanol and a cold D.I.. water for 1 h and 15 miin respectiveely. Pt meshh was used aas the counteer electrodee in a two-eleectrode cell configuratio on with the T Ti electrode iimmersed inn the electrollyte. Samples were anodizzed in electro olyte contain ning 0.1M N NH4F and
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