Application of Highly Functional Ti-Oxide-Based Photocatalysts in Clean Technologies

Abstract

Various Ti-oxide based photocatalysts such as the highly dispersed Ti-oxide species within zeolite frameworks, TiO 2 nano-particles hybridized with hydrophobic zeolite adsorbents as well as visible light responsive TiO 2 thin films have been successfully prepared. Characterization studies at the molecular level, such as X-ray absorption fine structure (XAFS) and photoluminescence (PL), revealed that the highly dispersed Ti-oxide species within the nano-spaces of zeolites possess a tetrahedral coordination and that they demonstrate unique and high performance for the photocatalytic decomposition of NOx and the photocatalytic reduction of CO 2 with H 2 O. A high photocatalytic reactivity for the TiO 2 semiconducting photocatalysts could be achieved by blending them with hydrophobic siliceous zeolites which was equal to the performance of TiO 2 deposited with expensive Pt particles. The role of the siliceous zeolites can be described as a so-called ''catch and release effect of organic compounds'', i.e., (i) the condensation of the reactants within the hydrophobic cavities of zeolites and; (ii) the efficient diffusion of the reactant onto the TiO 2 photocatalytic sites. Furthermore, a novel photocatalytic system which can convert abundant solar energy into renewable H 2 energy by the decomposition of H 2 O into H 2 and O 2 can also be achieved by using visible light responsive TiO 2 thin film photocatalysts prepared by a RF-magnetron sputtering deposition method. The conversion efficiency of solar energy into H 2 energy may be estimated at ca. 0.1% from the initial rate of H 2 evolution.

Photocatalytic Conversion of CO2 into Renewable Hydrocarbon Fuels: State‐of‐the‐Art Accomplishment, Challenges, and Prospects

“…Zeolites are representative micro/mesoporous materials that have been widely modified with TiO 2 photocatalysts for CO 2 reduction by taking advantage of their high surface area, high pore volume, tunable pore size, and good thermal and mechanical stability . The role of the siliceous zeolites can be described as a so‐called ‘‘catch and release effect of CO 2 ’’, i.e., i) the condensation of the reactants within the hydrophobic cavities of zeolites and ii) the efficient diffusion of the reactant onto the TiO 2 active sites . Ti‐containing zeolites shows improved CO 2 adsorption, reactivity, and selectivity of the products, including TS‐1, Ti‐oxide/Y‐zeolite, Ti‐MCM‐41, Ti‐MCM‐48, Ti‐FSM‐16 mesoporous zeolite, and Ti− β zeolite .…”

A review of TiO2 nanoparticles

“…Takeuchi et al [122] prepared various Ti oxide-based photocatalysts such as highly dispersed Ti oxide species within zeolite frameworks, TiO 2 nanoparticles hybridized with hydrophobic zeolite adsorbents and TiO 2 thin films responsive to visible light. A high photocatalytic reactivity was observed for the photocatalytic decomposition of NO x and the photocatalytic reduction of CO 2 with H 2 O using the TiO 2 semiconducting photocatalysts.…”

Synthesis of by the Flux Method

“…The electrons of oxide photocatalysts are excited from the valence band to the conduction band by the absorption of light with energy equal to or greater than the band gap, resulting in the generation of electrons and holes that then undergo redox reaction [2]. This behavior has been linked to the decomposition of organic substances [3,4].…”