Photocatalytic and photoelectrochemical water splitting over ordered titania nanotube arrays

Download

index.pdf

Date

2009

Author

Karslıoğlu, Osman

Metadata

Show full item record

Item Usage Stats

310
views

340
downloads

The objective of this study was to investigate photocatalytic water splitting over ordered TiO2 nanotube arrays. Synthesis of ordered nanotube arrays of titania, as a micron thick film on a titanium foil was accomplished by electrochemical anodization methods defined in the literature. Effect of two types of electrolyte (aqueous and organic) on the micro-morphology was observed by scanning electron microscopy. Optimum anodization times for the TiO2 nanotube electrodes, synthesized in ethylene glycol electrolyte, were different for acidic and basic electrolytes. Optimum times were determined as 2 hours in acidic and 4 hours in basic solutions. An H-type cell was constructed using a two side anodized titanium foil aiming the photocatalytic, stoichiometric and separate evolution of H2/O2 from the splitting of water. Gas evolution was observed at a rate of approximately 1 mL/h in the anode and 0.5 mL/h in the cathode, which implied the reverse of the desired stoichiometry. As the surface was corroded in that experimental conditions, electrochemical properties of the synthesized films were investigated by cyclic voltammetry (CV) at milder conditions. CV showed the reduction of Ti4+ to Ti3+, beginning at -0.2 V (vs. Ag/AgCl). Since the process is accompanied by proton intercalation to the oxide, non-annealed samples showed higher currents in that region. Non-annealed samples showed no photocurrent. Photocurrents obtained in this work, on the average 0.1-0.2 mA/cm2, were one order of magnitude lower than the similar studies in the literature.

Subject Keywords

Chemical engineering.

URI

http://etd.lib.metu.edu.tr/upload/3/12610388/index.pdf
https://hdl.handle.net/11511/18454

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Comparison of Fenitrothion and Trifluralin Adsorption on Organo-Zeolites and Activated Carbon. Part II: Thermodynamic Parameters and the Suitability of the Kinetic Models of Pesticide Adsorption LÜLE ŞENÖZ, Güzide Meltem; Atalay, Mustafa Ümit (Informa UK Limited, 2014-07-04) The suitability of two kinetic models and the thermodynamic parameters of pesticide adsorption were investigated based on obtained data of previous studies. Kinetic evaluation indicated that the pesticides adsorption on adsorbents followed the pseudo-second-order model. Gibbs free energy (Delta G degrees), enthalpy (Delta H degrees), and entropy (Delta S degrees) were calculated for thermodynamic parameters by using linearized Arrhenius equation. The results indicated that the sorption process of fenitrothi...
Quantum chemical simulation of nitric oxide reduction by ammonia (scr reaction) on v2o5 / tio2 catalyst surface Soyer, Sezen; Önal, Işıl; Department of Chemical Engineering (2005) The reaction mechanism for the selective catalytic reduction (SCR) of nitric oxide by ammonia on (010) V2O5 surface represented by a V2O9H8 cluster was simulated by density functional theory (DFT) calculations. The computations indicated that SCR reaction consisted of three main parts. In the first part ammonia activation on Brønsted acidic V-OH site as NH4+ species by a nonactivated process takes place. The second part includes the interaction of NO with pre-adsorbed NH4 + species to eventually form nitros...
MASS TRANSFER AND CHEMICAL REACTION IN A POWER-LAW SPHERE AT INTERMEDIATE REYNOLDS NUMBERS Gürkan, Türker (Informa UK Limited, 1990-3) The relevant mass transport equations have been numerically solved to determine the effect of power-law behavior in the dispersed phase. It is concluded that increased pseudoplasticity in the dispersed phase causes decreases in the total amount of mass transferred, C¯lt, to the droplet because of reduced circulation velocities. Maximum decreases in C¯lt, with increasing pseudoplasticity are realized for larger Peclet number, larger values of the ratio of the viscosity of the dispersed to continuous phase an...
Kinetic studies for the production of tertiary ethers used as gasoline additives Boz, Nezahat; Doğu, Timur; Department of Chemical Engineering (2004) In the present study, the kinetics studies for etherification reactions were investigated in detail. In the first phase of present study, different acidic resin catalysts were prepared by the heat treatment of Amberlyst-15 catalysts at 220°C at different durations of time and also by the synthesis of sulfonated styrene divinylbenzene cross-linked resins at different conditions. A linear dependence of reaction rate on hydrogen ion-exchange capacity was in 2M2B+ethanol reaction. However, in the case of 2M1B+e...
Experimental investagation of drag reduction effects of polymer additives on turbulent pipe flow Zeybek, Şerife; Uludağ, Yusuf; Department of Chemical Engineering (2005) Since the discovery of the drag reduction effects of even small amount of macromolecules in solutions in turbulent pipe flows, there have been many experimental and theoretical studies in order to understand mechanisms behind this phenomenon. Theories have been proposed based on the observations on the change in the characteristics of the turbulent flow near the pipe wall where friction of the momentum transfer between the flow and the conduit takes place. In this study drag reduction in fully developed tur...

Citation Formats

O. Karslıoğlu, “Photocatalytic and photoelectrochemical water splitting over ordered titania nanotube arrays,” M.S. - Master of Science, Middle East Technical University, 2009.