A new route for the synthesis of highly-active N-doped TiO2 nanoparticles for visible light photocatalysis using urea as nitrogen precursor.
- Resource Type
- Article
- Authors
- Marques, Juliana; Gomes, Tiago D.; Forte, Marta A.; Silva, Rui F.; Tavares, Carlos J.
- Source
- Catalysis Today. Apr2019, Vol. 326, p36-45. 10p.
- Subject
- *NANOPARTICLES
*VISIBLE spectra
*PHOTOCATALYTIC oxidation
*DOPING agents (Chemistry)
*METHYLENE blue
- Language
- ISSN
- 0920-5861
Graphical abstract Highlights • Synthesis temperature influences appearance and properties of the nanoparticles. • Nitrogen-doping increases visible-light photocatalytic activity. • The nitrogen content in TiO 2 powders was strongly affected by synthesis routes. • 1.4 at.% of N doping induces the highest specific surface area ∼200 m2. g−1. Abstract Nitrogen-doped TiO 2 nanoparticles with high specific surface area and photocatalytic activity under visible light were successfully produced using a modified sol-gel method with urea introduced as the nitrogen source. Different synthesis approaches and parameters such as doping temperature and urea to TiO 2 molar ratio were tested to examine the best outcome regarding photocatalytic activity for both UV-A and visible light irradiation. UV–vis diffuse reflectance characterization revealed a decrease in band gap from 3.24 to a minimum of 2.79 eV with the N-doping process. The photocatalytic Methylene Blue dye degradation assays suggests that the introduction of nitrogen in the TiO 2 lattice cell can provide a higher efficiency under both UV-A and visible irradiation. The maximum photocatalytic activity was achieved for the nitrogen-doped powders prepared with the lowest urea:TiO 2 molar ratio (1.5) as it was the formulation that promoted an enhancement in N-doping and particle specific surface area to 182 m2 g−1, despite the fact that the highest specific surface area was registered for undoped TiO 2 nanoparticles (228 m2 g−1). A synthesis step variation was performed to enhance the specific surface area of nanoparticles and consequently the photocatalytic activity. This modification promoted an increase in specific surface area by a factor of ∼5. XPS spectra confirmed a successful introduction of nitrogen in the TiO 2 lattice up to 1.5 at.% for optimized powders, which is strongly dependant of the type of synthesis and the amount of dopant species added during the doping process. [ABSTRACT FROM AUTHOR]