Fabrication and photocatalysis of nanostructured TiO 2 for solar hydrogen production P. Wongwanwattana a , P. Krongkitsiri b , P. Limsuwan c , U. Tipparach a, * a Department of Physics, Ubon Ratchathani University, Warinchamrab, Ubon Ratchathani, 34190, Thailand b Department of Science and Mathematics, Rajamangkala University of Technology Isan, Sakon Nakorn, 47160, Thailand c Department of Physics, King Mongkut’s University of Technology Thonburi, Bangkok, 10140, Thailand Available online 24 May 2011 Abstract Photoelectrochemical cells (PEC) based on metal-doped (Be and Fe) and Pt-loaded nanostructured-TiO 2 films were fabricated to make working electrodes for solar hydrogen production. Anatase nanocrystalline titania (nano-TiO 2 ) thin films were deposited on glass slide and Ti metal sheet substrates by a sol–gel dip-coating method. Titanium tetraisopropoxide was used as a precursor. The synthesis process and annealing temperatures play an important role on the crystallite size and the phase transformation of nano-TiO 2 . The diameter of the particles in the rage of 5–50 nm was obtained in different methods of making the sol-gels and annealing temperatures. Without an external applied potential, the photocurrent density of Be-doped PEC occurred of 0.32 mA/cm 2 under illumination of 75 mW/cm 2 and the device produced hydrogen by water photoelectrolysis at the rate of 0.1 ml/h cm 2 , with a photoconversion efficiencies of 0.52%. The maximum photocurrent density of Fe-doped PEC occurred of 0.80 mA/ cm 2 without an external applied potential and under the illumination of 100 mW/cm 2 corresponding with photoconversion efficiency of 0.98%. Impurity phase and undesired phases may be the cause of electron–hole recombination that results in decreasing photocatalytic activity. Crown Copyright # 2011 Published by Elsevier Ltd and Techna Group S.r.l. All rights reserved. Keywords: A. Sol–gel processes; D. Titanium dioxide (TiO 2 ); E. Electrodes; Solar hydrogen production 1. Introduction Solar hydrogen production has become a topic of interna- tional interest and challenge since the discovery of photoelec- trolysis of water on titanium dioxide (TiO 2 ) by Fujishima and Honda [1]. TiO 2 has attracted a great deal of study due to its high catalytic activity, stability and environmentally sound property. The excitation of TiO 2 can only be stimulated by high energy ultraviolet (UV) irradiation region with energy at least 3.2 eV corresponding to a wavelength of 387.5 nm. This practically rules out the use of sunlight as energy source for the photoelectrolysis because the solar spectrum with energy at least 3.2 eV contains less than 4% of the entire energy [2]. To extend the light absorption of TiO 2 into the visible light region and prevent the recombination of excited electrons and holes for highly active photocatalysts, different preparation methods and various dopants have been carried out in many efforts. A wide range of metal ions, in particular transition metal ions such as beryllium, cobalt, aluminum, iron, and nickel [3] has been used as dopants for TiO 2 to enhance photocatalytic activity and extending absorption into the range of the visible light spectrum. In addition, noble metal loading such as Pt, Au and Pd has also been made to reduce electron–hole recombination [3]. Many research groups have developed methods to make better TiO 2 photoanodes. Several methods have been introduced to deposit TiO 2 films for photoanodes including anodization [4], chemical vapor deposition, CVD [5] and sol–gel [6]. Among different methods of film deposition, sol–gel dip-coating is the simplest, cheapest and the most convenient. In this work, we present the fabrication of Be and Fe-doped and Pt-loaded TiO 2 as well as photoelectrolysis efficiency of TiO 2 nanocrystalline working electrodes for solar hydrogen generation. 2. Experimental TiO 2 films were prepared by sol–gel dip-coating on transparent conducting oxide (TCO) glass substrates. The www.elsevier.com/locate/ceramint Available online at www.sciencedirect.com Ceramics International 38S (2012) S517–S519 * Corresponding author. Tel.: +66 45 288381; fax: +66 45 288381. E-mail address: udomt@hotmail.com (U. Tipparach). 0272-8842/$36.00. Crown Copyright # 2011 Published by Elsevier Ltd and Techna Group S.r.l. All rights reserved. doi:10.1016/j.ceramint.2011.05.066