Influence of Nd-Doping on Photocatalytic Properties of TiO2Nanoparticles and Thin Film Coatings

Damian Wojcieszak,Danuta Kaczmarek,Jaroslaw Domaradzki,Leszek Kepinski,Kamil Chojnacki,Michal Mazur,Michalina Kurnatowska

doi:10.1155/2014/463034

Abstract

Structural, optical, and photocatalytic properties of TiO2and TiO2:Nd nanopowders and thin films composed of those materials have been compared. Titania nanoparticles with 1, 3, and 6 at. % of Nd-dopant were synthesized by sol-gel method. Additionally, thin films with the same material composition were prepared with the aid of spin-coating method. The analysis of structural investigations revealed that all as-prepared nanopowders were nanocrystalline and had TiO2-anatase structure. The average size of crystallites was ca. 4-5 nm and the correlation between the amount of neodymium and the size of TiO2crystallites was observed. It was shown that the dopant content influenced the agglomeration of the nanoparticles. The results of photocatalytic decomposition of MO showed that doping with Nd (especially in the amount of 3 at. %) increased self-cleaning activity of the prepared titania nanopowder. Similar effect was received in case of the thin films, but the decomposition rate was lower due to their smaller active surface area. However, the as-prepared TiO2:Nd photocatalyst in the form of thin films or nanopowders seems to be a very attractive material for various applications.

Highlights

The removal of inorganic and nonbiodegradable organic compounds is a crucial ecological problem
This kind of traps may decrease the recombination rate of e−/h+ pairs and it may increase the lifetime of charge carriers, which causes that the photocatalytic activity is more efficient [29]
An explanation of the effect of neodymium dopant on the photocatalytic activity of titania requires a consideration of the role of Ti– O–Nd bonds in the mechanism of indirect transfer of photogenerated carriers

Summary

Introduction

The removal of inorganic and nonbiodegradable organic compounds is a crucial ecological problem. The authors suggest that electrons from neodymium energy levels or from DS are trapped (EC: icenrleecatthtrieoonnfoocrfampsuatutpiroeirnnogxo)ifdbeyhsyOOdr22o∙(x(ayrclacderipacdtaoilcraas)nlsiwo(nhOsicH)ht∙h)r.aetsDupulatrrsitniicngipttahhteee light exposure holes (positively charged vacancies) are created in the TiO2 valance band They are responsible for the extraction of electrons from water and hydroxyl species to produce OH∙, which oxidizes (decomposes) dye molecules on the surface. When the Nd-dopant content exceeds a certain level, an excessive amount of Nd2O3 on the surface of titania would inhibit the adsorption of the dye and decrease the light absorption, decreasing the photocatalytic activity From this reason, titanium dioxide doped with an adequate amount of neodymium could have higher photocatalytic activity and would be much better suited to the role of commercial photocatalyst as compared to undoped TiO2. The thin films were prepared using spin-coating method and their photocatalytic properties were determined in order to compare self-cleaning activity of prepared nanoparticles and thin films

Experimental

Results and Discussion

Conclusions