Preparation and characterization of Sn/La co-doped TiO2 nanomaterials and their phase transformation and photocatalytic activity

Abstract

The pure, tin (Sn)-doped, lanthanum (La)-doped and Sn/La co-doped titanium dioxide (TiO2) nanomaterials were synthesized using sol-gel method followed by calcination at the temperature of 360 °C, 450 °C and 600 °C, respectively. The structures of the nanomaterials were characterized by X-ray diffraction (XRD), Thermogravimetric (TG), Differential Thermal Analysis (DTA), Scanning Electron Microscopy (SEM), Energy Dispersive Spectrum (EDS), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectrum (XPS), Diffuse Reflectance Spectrum (DRS), Photoluminescence Spectrum (PL), Brunauer-Emmett-Teller Measurements (BET), respectively. The photocatalytic property of the photocatalysts under UV light was evaluated through the degradation of Rhodamine B (RhB). The results show that the anatase-rutile phase transition is promoted by Sn-doping while La-doping retards the phase transition. However, La doping plays a major role in the process of phase transformation. The photocatalytic activity of pure TiO2 is affected by annealing temperature remarkably and the optimal annealing temperature is 450 °C. The photocatalytic activity of TiO2 is enhanced significantly by Sn and La doping at three different temperatures. Sn/La-TiO2 exhibits the highest degradation rates and the fastest reaction rates probably owing to the synergistic effect of Sn4+ and La3+ ions in inhibiting the recombination of photogenerated electron-hole pairs. The formation of extra surface hydroxyl groups and additional surface area are also beneficial for the photocatalytic activity.

La-Ce doped TiO2 nanocrystals: a review on synthesis, characterization and photocatalytic activity

“…But in La doped TiO 2 , the exothermic peak corresponding to phase transformation is observed at 600 °C. This indicates that La doping suppresses phase transformation of TiO 2 which is in agreement with XRD data [3,11]. The TG curve of La/Sn co-doped TiO 2 shows three step weight loss in which the first step results from the evaporation of physically absorbed water, the second step can be attributed to the combustion of organic compounds and the third step derives from the dehydroxylation of gel.…”

“…That is, in co-doped TiO 2 , recombination rate of photo-generated pair is minimum and separation rate is maximum. This increased separation rate is favourable for photocatalytic activity [3]. The intensity of PL spectra of La/B co-doped TiO 2 is low compared to pure and singly doped TiO 2 .…”

“…Titanium dioxide (TiO 2 ) is the best semiconductor photocatalyst used for environmental remediation such as destruction of toxic organic compounds, inactivation of organisms in water and air and energy conversion process. Properties like high stability, oxidative power, nontoxicity, low cost and high photo degradation efficiency makes TiO 2 the best one [1][2][3]. The extent and nature of crystalline phase (anatase, rutile, brookite) determines the intrinsic properties of titaniawhich is useful in many applications [4].…”

“…To prevent the anatase to rutile transformation and to inhibit its particle growth different types of dopants can be added. Lanthanum is the most important rare earth metal used for this because it increases the thermostability of anatase phase whose photocatalytic activity is much greater than that of rutile phase [3]. Modification of nano TiO 2 by doping with non-metals will cause the absorption edge to shift to visible region and the band width will become narrow.…”

Benign Hydrothermal Synthesis of N‐doped TiO2 and TiO2‐CoS Nanostructures for Enhanced Visible‐Light Driven Photocatalytic Activity

“…Besides doping and coupling with other suitable semiconductors, other strategies such as, dimensional consideration with increased specific surface area, preparation of high reactive facet‐dominated single nano‐crystal, and formation of core‐shell heterostructures exploiting the plasmonic enhancement effect have been adopted by the researchers to improve the photocatalytic activity of pure TiO 2 . This present work aims at the preparation of N‐doped TiO 2 ‐CoS nanocomposite‐ for the first‐time‐ towards environmental remediation with highlighting of preliminary results.…”