Study of the photocatalytic activity of Fe3+, Cr3+, La3+ and Eu3+ single-doped and co-doped TiO2 catalysts produced by aqueous sol-gel processing

Abstract

An aqueous sol-gel process, previously developed for producing undoped and Cu 2+ , Ni 2+ , Zn 2+ or Pb 2+ doped TiO 2 photocatalystswith remarkably high photocatalytic activity without requiring any calcination step, has been adapted to produce Fe 3+ , Cr 3+ , La 3+ or Eu 3+ singledoped TiO 2 photocatalysts as well as La 3+-Fe 3+ and Eu 3+-Fe 3+ co-doped TiO 2 catalysts. The physicochemical properties of the obtained catalysts have been characterized using a suite of complementary techniques, including ICP-AES, XRD, UV-Vis spectroscopy, nitrogen adsorption-desorption and Fe-57 Mössbauer. The active crystalline phase is obtained without requiring any calcination step and all the different catalysts are composed of nanocrystallites of anatase with a size of 6-7 nm and a high specific surface area varying from 181 to 298 m² g-1. In this study, the effect of the NO 3 :Ti(IV) mole ratio used to induce the peptisation reaction during the synthesis has been studied and the results revealed that this ratio can influence significantly the textural properties of the resulting catalyst. A screening of the photocatalytic activity of the undoped and Fe 3+ , Cr 3+ , La 3+ or Eu 3+ singledoped and co-doped photocatalysts has been performed by evaluating the degradation of 4nitrophenol under UV-Visible light (330 nm <λ< 800 nm). This study suggests that the photocatalytic activity is significantly influenced by the dopant nature and content with an optimal dopant content being observed in the case of Fe 3+ or La 3+ single-doped as well as in the case of La 3+-Fe 3+ and Eu 3+-Fe 3+ co-doped catalysts. In the case of Cr 3+ single-doped catalysts, a detrimental effect of the dopant on the photocatalytic degradation of 4-nitrophenol has been observed while no significant influence of the dopant has been detected in the case

Experimental Design and Optimization of Triclosan and 2.8-Diclorodibenzeno-p-dioxina Degradation by the Fe/Nb2O5/UV System

“…Analyzing the values obtained in relation to the nominal metallic load of Fe, it was observed that the band gap is likely to decrease with an increase in the Fe quantity. This also happens with samples of iron-doped TiO 2 catalysts [30,31]. It obtained the following values for the calcination temperature at 673 K (0.5% Fe-4.75 eV and 1.5% Fe-3.28 eV).…”

“…Afterward, it was then calcined at different temperatures (633, 673, 773, 873, and 913 K) with heating ramps. (ii) Catalytic immobilization-for the catalyst immobilization, it used a methodology adapted from Reference [31], which incorporated sodium alginate as the polymer matrix. The concentrations used were: sodium alginate 2% (w/v) and photocatalyst 1g L −1 .…”

Visible Light Sensitive SnO2/ZnCo2O4 Material for the Photocatalytic Removal of Organic Pollutants in Water

“…The absorbance spectra were transformed using the Kubelka-Munk function [10,64,65] to produce a signal, normalized for comparison between samples, and so to calculated the band gaps (Eg,direct and Eg,indirect). The details of this treatment method have been widely described elsewhere [53,54,66].…”

Effects of Ag0-modification and Fe3+-doping on the structural, optical and photocatalytic properties of TiO2

“…Besides, TiO 2 modication by metal ion doping has also been extensively studied. [20][21][22][23][24] Wu et al 25 synthesized Cu-doped TiO 2 by hydrothermal synthesis and air heat treatment. 0.5 mol%-Cu/TiO 2 shows better photocatalytic activity than pure TiO 2 because it enlarges the visible light absorbance due to the presence of Cu 3d orbitals.…”

“…Meanwhile, some studies have shown that single element displays better modication effect than multi-elements. 24,29 Khan et al's research 29 indicates that Ga-doped TiO 2 exhibits better photocatalytic performance than N/Ga co-doped TiO 2 . Malengreaux et al 24 reported that Eu/Fe co-doped TiO 2 shows lower photocatalytic efficiency than Fedoped TiO 2 and pure TiO 2 .…”