Photocatalysis

About: Photocatalysis is a research topic. Over the lifetime, 67088 publications have been published within this topic receiving 2145233 citations. The topic is also known as: photocatalyst.

Parameters affecting the photocatalytic degradation of dyes using TiO2: a review

Abstract: Traditional chemical, physical and biological processes for treating wastewater containing textile dye have such disadvantages as high cost, high energy requirement and generation of secondary pollution during treatment process. The advanced oxidation processes technology has been attracting growing attention for the decomposition of organic dyes. Such processes are based on the light-enhanced generation of highly reactive hydroxyl radicals, which oxidize the organic matter in solution and convert it completely into water, CO2 and inorganic compounds. In this presentation, the photocatalytic degradation of dyes in aqueous solution using TiO2 as photocatalyst under solar and UV irradiation has been reviewed. It is observed that the degradation of dyes depends on several parameters such as pH, catalyst concentration, substrate concentration and the presence of oxidants. Reaction temperature and the intensity of light also affect the degradation of dyes. Particle size, BET-surface area and different mineral forms of TiO2 also have influence on the degradation rate.

Kinetics studies in heterogeneous photocatalysis. I. Photocatalytic degradation of chlorinated phenols in aerated aqueous solutions over titania supported on a glass matrix

Abstract: The photocatalytic degradation of phenol, 4-chlorophenol, 2,4-dichlorophenol, and 2,4,5-trichlorophenol over TiO/sub 2/ (anatase) has been investigated by using three photochemical reactors. TiO/sub 2/ was used as a thin film, coating the internal surface of a glass coil (reactors I and II) or the external surface of glass beads (reactor III). The degradation of the four phenolic compounds, in a continuous recirculation mode in all three reactors, approximates first-order kinetics to near-complete degradation. The Langmuir-Hinshelwood kinetics have been modified slightly to rationalize the first-order behavior in solid-liquid reactions and to argue in favor of a surface reaction; the degradation reactions occur on the TiO/sub 2/ particle surface. In the multipass mode experiments, both reactors I and II exhibit higher degradation rates for phenol at the higher flow rates. By contrast, the greater degradation is associated with the lower flow rates in the single-pass mode experiments.

Photocatalysis and Photoinduced Hydrophilicity of Various Metal Oxide Thin Films

Abstract: Thin films of various metal oxides were prepared on glass substrates by a wet process to determine their photocatalytic ability to decompose adsorbed dye and to evaluate their photoinduced hydrophilicity under UV illumination. The metal oxides used in this study are classified into four categories based on their behavior over the two photochemical reaction: (1) active in both photocatalytic oxidation and photoinduced hydrophilicity (TiO2, SnO2, ZnO); (2) only active in photocatalytic oxidation (SrTiO3); (3) only active in photoinduced hydrophilicity (WO3, V2O5); (4) and inactive over both processes (CeO2, CuO, MoO3, Fe2O3, Cr2O3, In2O3). X-ray photoelectron spectroscopy revealed that oxygen defect sites were produced by Ar+ bombardment on the surface of metal oxides, showing photoinduced hydrophilicity. These results indicate that photoinduced hydrophilicity is not induced by the photocatalytic oxidation of organic compounds adsorbed on the surface, but is based on structural changes of the metal oxide s...

Visible-light photocatalytic, solar thermal and photoelectrochemical properties of aluminium-reduced black titania

Abstract: Utilizing solar energy for hydrogen generation and water cleaning is a great challenge due to insufficient visible-light power conversion. Here we report a mass production approach to synthesize black titania by aluminium reduction. The obtained sample possesses a unique crystalline core–amorphous shell structure (TiO2@TiO2−x). The black titania absorbs ∼65% of the total solar energy by improving visible and infrared absorption, superior to the recently reported ones (∼30%) and pristine TiO2 (∼5%). The unique core–shell structure (TiO2@TiO2−x) and high absorption boost the photocatalytic water cleaning and water splitting. The black titania is also an excellent photoelectrochemical electrode exhibiting a high solar-to-hydrogen efficiency (1.7%). A large photothermic effect may enable black titania “capture” solar energy for solar thermal collectors. The Al-reduced amorphous shell is proved to be an excellent candidate to absorb more solar light and receive more efficient photocatalysis.

Ultra-thin nanosheet assemblies of graphitic carbon nitride for enhanced photocatalytic CO2 reduction

Abstract: A two-dimensional layered polymeric photocatalyst, graphitic carbon nitride (g-C3N4), is becoming the rising star in the field of solar-to-fuel conversion. However, the performance of commonly prepared g-C3N4 is usually very weak because of the high recombination rate of photogenerated charge carriers and a small amount of surface active sites. Here we demonstrate simultaneous texture modification and surface functionalization of g-C3N4via a stepwise NH3-mediated thermal exfoliation approach. The resulting g-C3N4 photocatalyst possesses a hierarchical structure obtained by the assembly of amine-functionalized ultrathin nanosheets and thus exhibits remarkably enhanced light harvesting, a high redox ability of charge carriers, increased CO2 adsorption and a larger amount of surface active sites, as well as improved charge carrier transfer and separation. Therefore the aforementioned hierarchical g-C3N4 consisting of amine-functionalized ultra-thin nanosheets shows much better performance for photocatalytic CO2 reduction than unmodified conventional g-C3N4 photocatalysts.