Photocatalytic degradation of phenol on different phases of TiO(2) particles in aqueous suspensions under UV irradiation.

Photocatalytic degradation of phenol on different phases of TiO(2) particles was examined under 400-W UV irradiation. The effects of various operating parameters including TiO(2) dosage, solution pH (4-10), and initial phenol concentration (0.13-1.05 mM) on phenol degradation were investigated. Three forms of TiO(2) photocatalysts such as pure anatase phase, pure rutile phase, and the mixed phase were prepared by sol-gel method and followed annealing at different temperatures. The annealing temperature used were 500 °C, 700 °C and 900 °C for pure anatase phase, the mixed phase, and pure rutile phase, respectively. It was shown that pure anatase TiO(2) exhibited higher photocatalytic activity than the physical mixture of pure anatase and rutile TiO(2). Moreover, the TiO(2) particle with a specific fraction of mixed anatase and rutile phases exhibited better performance than pure anatase TiO(2). Finally, the degradation rate could be satisfactorily fitted by a pseudo-first-order kinetic model.

Three-dimensional electrodes for dye-sensitized solar cells: synthesis of indium-tin-oxide nanowire arrays and ITO/TiO2 core-shell nanowire arrays by electrophoretic deposition.

Dye-sensitized solar cells (DSSCs) show promise as a cheaper alternative to silicon-based photovoltaics for specialized applications, provided conversion efficiency can be maximized and production costs minimized. This study demonstrates that arrays of nanowires can be formed by wet-chemical methods for use as three-dimensional (3D) electrodes in DSSCs, thereby improving photoelectric conversion efficiency. Two approaches were employed to create the arrays of ITO (indium-tin-oxide) nanowires or arrays of ITO/TiO(2) core-shell nanowires; both methods were based on electrophoretic deposition (EPD) within a polycarbonate template. The 3D electrodes for solar cells were constructed by using a doctor-blade for coating TiO(2) layers onto the ITO or ITO/TiO(2) nanowire arrays. A photoelectric conversion efficiency as high as 4.3% was achieved in the DSSCs made from ITO nanowires; this performance was better than that of ITO/TiO(2) core-shell nanowires or pristine TiO(2) films. Cyclic voltammetry confirmed that the reaction current was significantly enhanced when a 3D ITO-nanowire electrode was used. Better separation of charge carriers and improved charge transport, due to the enlarged interfacial area, are thought to be the major advantages of using 3D nanowire electrodes for the optimization of DSSCs.

Photocatalytic degradation of phenol in aqueous solutions by Pr-doped TiO2 nanoparticles.

Photocatalytic degradation of phenol in water was examined using Pr-doped TiO(2) nanoparticles. These photocatalysts were synthesized by an acid-peptized sol-gel method from titanium tetra-isopropoxide with different concentrations of Pr(III) dopant and calcination temperatures. Several tools such as XRD, BET surface area, SEM, and EDX, were used to evaluate particle structure, size distribution, and composition. The optical absorption properties of the prepared particles were also measured. Photocatalytic activity of the particles was studied in a batch reactor containing phenol solution with 400W UV irradiation. Parameters affecting photocatalytic process such as the catalyst crystallinity, light absorption efficiency, the dosage of catalyst, dopant and phenol concentrations were investigated. The Pr-doped TiO(2) showed high activity for photocatalytic degradation of phenol. The presence of Pr ions in the TiO(2) particles would cause a significant absorption shift towards the visible region. The degradation process was optimized using 1g/L Pr-doped TiO(2) with a Pr(III) concentration of 0.072 mol% after 2h irradiation. It was shown that photodegradation followed a pseudo-first-order kinetics and the rate constant changed with phenol concentration.