Effects of Ag Nanoparticles on Zinc Oxide Photocatalytic Performance

Mouna Khiari,Florica Lazar,Aomar Hadjadj,Mickaël Gilliot,Michaël Lejeune

doi:10.3390/coatings11040400

Mouna Khiari, Florica Lazar + Show 3 more

Open Access

https://doi.org/10.3390/coatings11040400

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Abstract

We used a sol–gel spin coating technique to synthesize nanocomposite thin films based on zinc oxide (ZnO) loaded with silver nanoparticles (NPs). We tested these ZnO/Ag NPs photocatalysts, with a thickness of about 100 nm, for the photodegradation of the indigo carmine dye solution. The study focused on the effects of Ag NPs on the ZnO matrix as well as the impact of their concentration on the photocatalytic performance of the nanocomposite. The study also highlighted the high stability of the photocatalytic performance of these nanocomposites. This work is a contribution in the search for non-toxic thin film photocatalysts that is usable under solar radiation for the treatment of contaminated wastewater. Innovation in the field of heterogeneous photocatalysis requires the use of solar resource with efficient results in terms of photocatalytic performance.

Highlights

Despite stringent environmental regulations, the global textile dyes market accounted for US $ 7.59 billion in 2019 and is expected to reach US$13.54 billion by 2027 [1]
Among wide-bandgap semiconductors eligible for the process of photocatalysis and dye degradation, special attention has been given to zinc oxide (ZnO)
When the photocatalyst is illuminated by a photon of energy hν ≥ Eg (UV light illumination), its absorption generates an electron (e− )–hole (h+ ) pair in, respectively, the conduction band (CB) and the valence band (VB) of the semiconductor (Figure 12a): (ZnO) + hν → e− + h+

Summary

Introduction

The global textile dyes market accounted for US $ 7.59 billion in 2019 and is expected to reach US$13.54 billion by 2027 [1]. This expected increase in the consumption of dyes will translate into an increase in water pollution since the major part of these dyes will eventually be discharged in wastewater. Among wide-bandgap semiconductors eligible for the process of photocatalysis and dye degradation, special attention has been given to zinc oxide (ZnO). Elaboration of nanocomposites based on a wide-gap semiconductor matrix in which metallic nanoparticles (NPs) are embedded seems like a promising way to achieve this goal. Due to the size of the metallic NPs, possible plasmon excitations should facilitate the charge transport and separation of charge carriers [23,24,25]

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