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Decahedral TiO 2 decorated with bimetallic nanoparticles were synthesized via radiolysis and photodeposition method. The effect of bimetallic surface composition (Ag_Pt, Ag_Au, Au_Pd, Au_Pt) as well as deposition technique (simultaneous or sequential) on the photocatalytic activity in phenol degradation and efficiency of hydroxyl radicals generation under UV–vis light irradiation were investigated. Modified and pristine decahedral TiO 2 anatase with exposed {001} were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM) with energy-dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), inductively coupled plasma-mass spectrometry (ICP-MS) and X-ray photoelectron spectroscopy (XPS). The gas chromatography-mass spectrometry was employed to detect organic intermediates to establish degradation pathway of isotopically labeled (1- 13 C) phenol. The modification with Pt and Ag nanoparticles induced an increase in photocatalytic activity of phenol degradation under UV–vis light irradiation (79% of phenol was degraded after 90 min of irradiation). The main by-products detected in phenol oxidation were catechol, hydroquinone, malonic, fumaric and maleic acid. The results indicated the formation of isotopically labeled and unlabeled maleic acid. It was noticed that all samples sequentially photodeposited on TiO 2 surface exhibited higher OH radicals generation compared to pristine TiO 2 . Our results suggest that synergistic effects between specifically engineered TiO 2 nanocrystals and unique properties of loaded bimetallic nanoparticles can enhance the charge separation of photoinduced carriers.

Perovskite-type oxides are a class of compounds with the general formula ABO 3 . They are a very important family of materials and exhibit properties suitable for numerous applications. In this review, the preparation, characterization, and application of selected perovskite oxides such as SrTiO 3 , KTaO 3 , NaTaO 3 , KNbO 3 , and NaNbO 3 in photocatalysis are described. In addition, various strategies for enhancing their photocatalytic activities are discussed, including doping with metals and nonmetals (Cr, Ni, Mn, Pb, Bi, N, Br, S, C, and F), modification with noble metal (Au, Ag, Pt, Pd, Ph, Ru) nanoparticles, and doping with rare earth elements (La). Moreover, the review summarizes the influence of different morphologies and surface properties on the photoactivity of the materials.

As an important metal oxide, titanium dioxide has been widely investigated because of its unique surface, electronic, and photocatalytic properties, which make this material applicable in many areas of science and technology ranging from adsorption, catalysis and photocatalysis to biomedicine, environmental monitoring and cleanup, energy conversion and storage, etc. The properties of anatase TiO 2 crystals are largely determined by external surfaces exposed. Since the breakthrough in synthesizing anatase TiO 2 single crystals with a large percentage of highly reactive (0 0 1) facets in 2008, many unusual properties and applications of these (0 0 1) facets dominant in anatase TiO 2 have been explored theoretically and experimentally, showing the industrial importance of this semiconductor material. Here we review the recent progress in synthesizing by various synthetic methods and photocatalytic activity TiO 2 with exposed crystal facets with different morphologies.

Preparation route of new tungsten-containing TiO2 powders (W-TiO2) and their activity under visible light are reported. The photocatalysts were prepared by the sol–gel method and by grinding anatase powder with a dopant precursor followed by calcinations (surface impregnation method). Tungsten oxide and tungsten hexacarbonyl were used as tungsten sources in both photocatalyst preparation procedure. The obtained photocatalysts were subsequently characterized by a BET method, X-ray photoelectron emission spectroscopy (XPS) and X-ray powder diffraction analysis (XRD). Degradation efficiency of phenol and formation of phenol degradation by-products were compared for two systems: W-doped TiO2 under visible light and P-25 under UV irradiation. The highest photoactivity under visible light was observed for 3%-W-TiO2 and it was three times higher than photoactivity of pure TiO2. Phenol oxidation in the presence of W-TiO2 and visible light leads to formation of hydroxyproduct (catechol) and phenol ring cleavage products (muconic aldehyde).

Our research examines the photoactivity under visible light (λ > 400 nm) and surface properties (BET surface area, UV–vis absorption properties, chemical composition and crystal structure) of boron-modified TiO2. B–TiO2 photocatalysts were prepared by surface impregnation procedure using boric acid triethyl ester (BATE) as a boron precursor. The photocatalytic activity of obtained powders in visible light was estimated by measuring the decomposition of phenol (0.21 mmol/dm3) in aqueous solution. The effect of boron content, calcination temperature and titanium dioxide source used during preparation procedure on photoactivity was investigated. The degradation of phenol indicated that the photoactivity under visible light strongly depended on preparation manner of B–TiO2 photocatalysts. The highest photoactivity was observed for the sample obtained by impregnation with 2 wt.% of BATE and calcinated at 400 °C. Phenol degradation rate, in the presence of these samples, equaled to 3.0 μmol dm−3 min−1. The mode of BATE binding to TiO2 surface is discussed.

Synthesis of new boron-containing TiO2 powders (B-TiO2) and their activity under UV and visible light are reported. The catalysts were prepared by the sol–gel method and by grinding anatase powder with a dopant. Boric acid triethyl ester and boric acid were used as boron sources in both catalysts preparation procedures. The photocatalytic activity of obtained powders in UV and visible light was estimated by measuring the decomposition rate of phenol (0.21 mmol/dm3) in an aqueous solution. Carbon and boron presence in all prepared photocatalysts was confirmed by the XPS technique. The oxidation state of B atoms incorporated in TiO2 particles was mainly B3+, as determined from the X-ray photoelectron spectra (XPS). It was confirmed that boron-doped TiO2 was activated by visible light and used as effective catalyst in photooxidation reactions.