Nitrogen-modified nano-titania: True phase composition, microstructure and visible-light induced photocatalytic NOx abatement


Titanium dioxide (TiO2) is a popular photocatalyst used for many environmental and anti-pollution applications, but it normally operates under UV light, exploiting similar to 5% of the solar spectrum. Nitrification of titania to form N-doped TiO2 has been explored as a way to increase its photocatalytic activity under visible light, and anionic doping is a promising method to enable TiO2 to harvest visible-light by changing its photo-absorption properties. In this paper, we explore the insertion of nitrogen into the TiO2 lattice using our green sol gel nanosynthesis method, used to create 10 nm TiO2 NPs. Two parallel routes were studied to produce nitrogen-modified TiO2 nanoparticles (NPs), using HNO3+NH3 (acid-precipitated base-peptised) and NH4OH (totally base catalysed) as nitrogen sources. These NPs were thermally treated between 450 and 800 degrees C. Their true phase composition (crystalline and amorphous phases), as well as their micro-/nanostructure (crystalline domain shape, size and size distribution, edge and screw dislocation density) was fully characterised through advanced X-ray methods (Rietveld-reference intensity ratio, RIR, and whole powder pattern modelling, WPPM). As pollutants, nitrogen oxides (NO) are of particular concern for human health, so the photocatalytic activity of the NPs was assessed by monitoring NO, abatement, using both solar and white-light (indoor artificial lighting), simulating outdoor and indoor environments, respectively. Results showed that the onset of the anatase-to-rutile phase transformation (ART) occurred at temperatures above 450 degrees C, and NPs heated to 450 degrees C possessed excellent photocatalytic activity (PCA) under visible white-light (indoor artificial lighting), with a PCA double than that of the standard P25 TiO2 NPs. However, higher thermal treatment temperatures were found to be detrimental for visible-light photocatalytic activity, due to the effects of four simultaneous occurrences: (i) loss of OH groups and water adsorbed on the photocatalyst surface; (ii) growth of crystalline domain sizes with decrease in specific surface area; (iii) onset and progress of the ART; (iv) the increasing instability of the nitrogen in the titania lattice. (C) 2015 Elsevier Inc. All rights reserved.






Tobaldi, DM; Pullar, RC; Gualtieri, AF; Otero-Irurueta, G; Singh, MK; Seabra, MP; Labrincha, JA

nossos autores


D.M. Tobaldi is grateful to the ECO-SEE project (funding from the European Union's Seventh Framework Programme for Research, Technological Development and Demonstration under Grant Agreement no. 609234. Note: The views expressed are purely those of the authors and may not in any circumstances be regarded as stating an official position of the European Commission). R.C. Pullar acknowledges the support of FCT Grant SFRH/BPD/97115/2013. Gonzalo Otero-Irurueta would like to thank FCT from Portugal for his Post-Doctoral research grant (SFRH/BPD/90562/2012). This work was developed in the scope of the project CICECO-Aveiro Institute of Materials (Ref. FCT UID /CTM /50011/2013), financed by national funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement. M. Ferro and RNME - University of Aveiro, FCT Project REDE/1509/RME/2005-are kindly acknowledged for HR-TEM analysis.

Partilhe este projeto

Publicações similares

Usamos cookies para atividades de marketing e para lhe oferecer uma melhor experiência de navegação. Ao clicar em “Aceitar Cookies” você concorda com nossa política de cookies. Leia sobre como usamos cookies clicando em "Política de Privacidade e Cookies".