Heat-induced enhancement of photocatalytic activity of laser-synthesized TiO₂ nanoparticles

Session

PSA.5 - Nanoparticles & Catalysts

Authors

Damjan Blazeka (1), Andreja Gajovic (3), Kresimir Salamon (3), Miran Ceh (2), Sandra Drev (2), Niksa Krstulovic (1), Julio Car (1)

Affiliations

1. Institute of Physics
2. Jozef Stefan Institute
3. Rudjer Boskovic Institute

Keywords

laser ablation, photocatalysis, TiO₂ nanoparticles, transmission electron microscopy

Abstract text

Pulsed laser ablation in liquid (PLAL) is method which allows synthesis of nanoparticles with very high purity compared to chemically synthesized nanoparticles. Due to its ecological acceptability PLAL is often reffered as "green method". High purity of laser-synthesized nanoparticles makes PLAL very promising technique for production of TiO₂ nanoparticles with large photocatalytic activity. In this project, we examined influence of heating treatment on photocatalytic activity of laser-synthesized TiO₂ nanoparticles.

Using laser ablation in water, performed with Nd:YAG laser with basic wavelength 1064 nm, in this work we synthesized amorphous titanium dioxide nanoparticles. The next experimental methods are used for nanoparticles analysis: UV-VIS and Raman spectroscopy, XRD, XPS, SAED, TEM/SEM microscopy. These are used to obtain optical properties, crystal structure and size distribution of nanoparticles. 

After laser synthesis, TiO₂ nanoparticles were heated for 6 hours on temperature 90°C. During this process nanoparticles have crystallized in the mixture of anatase and rutile phase. TiO₂ nanoparticles have LogNormal diameter distribution with maximal occurence at 8 nm before heating and 5 nm after heating. Photocatalytic photodegradation rate of Methylene Blue and Rhodamine B under UV radiation is measured and compared for amorphous, crystallized and commercial Aeroxide P25 TiO₂ nanoparticles. Crystallized nanoparticles have shown by far largest photocatalytic activity.

The largest contribution of this work is presentation of simple method for transformation of laser synthesized amorphous TiO₂ nanoparticles in the crystallized nanoparticles with high photocatalytic activity.

Acknowledgments: We thank to Croatian science foundation for research support and financial funding (HrZZ IP-2019-04-6418 and IP-2018-01-5246).