Zinc oxide nanocolloids prepared by picosecond pulsed laser ablation in water at different temperatures

Luisa D’Urso,Salvatore Spadaro,Saveria Santangelo,Giuseppe Compagnini,Fortunato Neri,Enza Fazio,Martina Bonsignore,L Torrisi,M Cutroneo

doi:10.1051/epjconf/201816704008

Luisa D’Urso, Salvatore Spadaro + Show 7 more

Open Access

https://doi.org/10.1051/epjconf/201816704008

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Abstract

Zinc oxide with wide direct band gap and high exciton binding energy is one of the most promising materials for ultraviolet (UV) light-emitting devices. It further exhibits good performance in the degradation of non-biodegradable pollutants under UV irradiation. In this work, zinc oxide (ZnO) and zinc oxide/gold (ZnO/Au) nanocolloids are prepared by picosecond pulsed laser ablation (ps-PLA), using a Zn and Au metallic targets in water media at room temperature (RT) and 80°C. ZnO and Au nanoparticles (NPs) with size in the 10–50 nm range are obtained at RT, while ZnO nanorods (NRs) are formed when water is maintained at 80°C during the ps-PLA process. Au NPs, added to ZnO colloids after the ablation process, decorate ZnO NRs. The crystalline phase of all ZnO nanocolloids is wurtzite. Methylene blue dye is used to investigate the photo-catalytic activity of all the synthesised nanocolloids, under UV light irradiation.

Highlights

Introductionzinc oxide (ZnO) looks as a very promising candidate for environmental applications because it is cheap, and has a great photo-catalytic activity, a strong oxidation ability, a direct and wide band-gap energy in the near-UV spectral region (3.3 eV at 300K), higher quantum efficiency compared to other wide band-gap semiconductors, and a large free-exciton binding energy (60 meV) so that exciton emission processes can persist at or even above the room temperature
We propose a simple and cheap physical approach to the synthesis of zinc oxide (ZnO) and Audecorated ZnO nanorods with no environmental impact
ZnO and Au nanocolloids were successfully synthesised by picosecond pulsed laser ablation, using Zn and Au metallic targets, in water media at room temperature (RT) and 80°C

Summary

Introduction

ZnO looks as a very promising candidate for environmental applications because it is cheap, and has a great photo-catalytic activity, a strong oxidation ability, a direct and wide band-gap energy in the near-UV spectral region (3.3 eV at 300K), higher quantum efficiency compared to other wide band-gap semiconductors, and a large free-exciton binding energy (60 meV) so that exciton emission processes can persist at or even above the room temperature. The relatively high recombination rate of generated electron-hole pairs reduces the efficiency of this photo-catalyst. The nanostructuration, resulting in a high surface-area/volume ratio, enhances the amount of the photo-generated charge carriers, whereas the addition of metal NPs on the photo-catalyst surface reduces recombination rate of the excited photoelectron-hole pairs. Materials produced are tested as catalysts for environmental applications, showing relatively high photo-degradation efficiency of methylene blue (MB) in aqueous solution under UV light irradiation

Experimental

Results and discussion

Conclusion