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

Abstract

Titanium dioxide (TiO 2) is one of the best semiconductor photocatalysts due to its high stability, oxidative power, nontoxicity, low cost etc. But its photocatalytic activity is limited due to rapid recombination of photo-generated electronhole pair, wide band gap and anatase to rutile phase transformation. These disadvantages can be eliminated by introducing dopants into the TiO 2 nanocrystals. Sol-gel and hydrothermal methods can be used for the synthesis of doped and co-doped TiO 2 nanocrystals. Advanced characterization techniques can be used for the study of phase structure, optical properties, thermal properties, surface area, morphological changes and photocatalytic activity of doped and co-doped TiO 2 nanoparticles. Doping inhibits the anatase to rutile phase transformation and suppresses the recombination of photo-generated electron-hole pair which enhances the photocatalytic activity. Here we made a review on the synthesis, characterization and photocatalytic activity of La, Ce doped and co-doped TiO 2 nanoparticles.

Phase Composition, Microstructure, and Optical Characteristics of Spin‐Coated La‐TiO2 and Fe–TiO2

“…The presence of La (at concentrations 1 mol% or w/w%) has been shown to cause the range of absorption of TiO 2 to move toward the visible spectrum. [49][50][51] However, the results in the present study do not agree with the previous literature due to the difference in the La ion concentrations employed. The maximum concentration that TiO 2 can accommodate depends upon the kind of foreign ions.…”

“…[52] In experimental studies, for metals with a larger ionic radius than Ti atoms, the maximum concentration allowable for doping is less than 5 w w À1 % or mol%. [46][47][48][49][50] Thus, it is expected that increasing from 5 to 10 mol% would cause no remarkable changes in the reflectance properties of TiO 2 .…”

Band Gap Tuning in Transition Metal and Rare-Earth-Ion-Doped TiO2, CeO2, and SnO2 Nanoparticles

“…In order to reduce the electron-hole recombination and to shift the absorption wavelength to the desired visible region ( nm), a decrease in the band gap of rare earth (RE)-doped TiO , CeO , and SnO bulk and nanoparticles (NPs) has been considered, which improves the absorption of visible light [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. Let us emphasize that there are also results with enhanced by increasing the RE ion concentration [ 7 , 34 ].…”

A review of scandium–hafnium doped TiO2 nanocrystals

“…Therefore TiO 2 can be modified by co-doping. The metal ion present in the TiO 2 may alter its properties and enhances the photocatalytic activity based on the metal [6]. When Sc or Hf is incorporated into TiO 2 , the variations in the properties are summarized in the Fig.…”