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BixTiyOz-Fe multiphase systems with excellent photocatalytic performance in the visible
摘要： New photocatalysts based on bismuth titanates doped with iron with outstanding visible photocatalytic activity were prepared by a facile hydrothermal method followed by incipient wetness impregnation. The starting material was composed by three phases; majority of Bi20TiO32 closely interconnected to Bi4Ti3O12 and amorphous TiO2. Fe doping increased the already very high visible activity of the original material. The high visible activity showed by these materials could be ascribed to a combination of several features; i.e. low band gap energy value (as low as 1.78 eV), a structure allowing a good separation path for visible photogenerated electron-holes pairs and a relatively high surface area. Fe doping could be acting as bonding paths for the bismuth titanates phases, and the amount of Fe on the surface was found to be a crucial parameter on the photocatalytic activity of the materials. Visible activity of the best photocatalyst was superior to UV-Activity of commercial TiO2 P25 used as reference in same experimental conditions.
关键词： Fe doping,Bi20TiO32,Bi4Ti3O12,Visible photocatalysis,Phenol degradation
更新于2025-09-04 15:30:14
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Effects of Operating Parameters on Photocatalytic Degradation of Methylene Blue or Phenol on Supported Titanium-Based Catalysts
摘要： Photocatalytic decompositions of both methylene blue and phenol in aqueous solutions were conducted separately on titanium-based catalysts. The catalysts were prepared using impregnation method on different supports (SiO2, Al2O3 or ZSM-5) and titanium precursors (TiO2 or TiCl4). They were tested in visible light or UV irradiations of different wavelengths (254 and 365 nm). The physico-chemical characteristics of the catalysts were obtained using BET, XRD, FTIR and TGA. The supports surface areas and porosities showed insignificant decreased after impregnation with the active components. The diffraction patterns showed strong peaks that are assigned to titania anatase phase and weaker peak that indicated low concentration of rutile phase. Irrespective of the support, FTIR showed broad peaks of Ti-O-Ti linkages in TiO2 particles. The catalysts were found to be active in decomposition of either methylene blue or phenol from aqueous solutions. For both methylene blue and phenol, the removal trend is TiO2/SiO2<TiO2/Al2O3<<TiO2/ZSM-5.
关键词： Titania,Phenol,Precursors,Methylene blue,Supports,Photocatalysis
更新于2025-09-04 15:30:14
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Nonresonant photons catalyze photodissociation of phenol
摘要： Phenol represents an ideal polyatomic system for demonstrating photon catalysis because of its large polarizability, well-characterized excited-state potential energy surfaces, and nonadiabatic dissociation dynamics. A nonresonant IR pulse (1064 nm) supplies a strong electric field (4 x 107 V/cm) during the photolysis of isolated phenol (C6H5OH) molecules to yield C6H5O + H near two known energetic thresholds: the S1/S2 conical intersection and the S1 - S0 origin. H-atom speed distributions show marked changes in the relative contributions of dissociative pathways in both cases, compared to the absence of the nonresonant IR pulse. Results indicate that nonresonant photons lower the activation barrier for some pathways relative to others by dynamically Stark shifting the excited-state potential energy surfaces rather than aligning molecules in the strong electric field. Theoretical calculations offer support for the experimental interpretation.
关键词： phenol,photodissociation,dynamic Stark shift,photon catalysis,nonresonant IR field
更新于2025-09-04 15:30:14