Zinc oxide (ZnO) photocatalyst has gained increased interest due to its unique properties, including biocompatibility, non-toxicity, and affordability. However, it shows a poor performance in visible light due to the wide band gap located in the UV region. The quick recombination of photo-generated electron-hole pairs limits its use on an industrial scale. The incorporation of silver nanoparticles (AgNP) in the structure of ZnO would help to improve the charge separation efficiency and, in turn, photocatalytic efficiency. Additionally, the decontamination of organic species using ZnO in the form of powder is an expensive process. The use of ZnO as thin film rather than powder is a way to avoid the additional procedures related to the separation or filtration of the powder to reuse. Diverse techniques have been proposed to prepare ZnO films, such as pulsed laser deposition, chemical vapor deposition and magnetron sputtering. Among those techniques, sol–gel method has received most attention since it yields high quality ZnO films at a low-cost and with a simple deposition procedure.
In this study, ZnO thin films doped with Ag nanoparticles (AgNP) have been deposited on Si-wafer and glass slide substrates using sol–gel dip coating method. AgNP suspensions were prepared using silver nitrate and polyvinylpyrrolidone as the stabilizer. The UV–Vis spectrum of AgNP suspension showed a typical absorption band at 406 nm, associated with the local surface plasmon resonance (LSPR) of spherical metallic Ag nanoparticles. On the other hand, the XRD results confirmed the presence of ZnO crystallizes with the hexagonal wurtzite structure.The photocatalytic activity was tested by the decomposition of methyl orange dye under solar light illumination using a solar simulator. ZnO thin films doped with AgNPs showed an enhanced photocatalytic activity compared to the films without AgNP. The AgNPs act as an electron trap, suppressing the electron-hole pair recombination and thus, increasing the photocatalytic efficiency.Keywords: ZnO thin films; Sol–gel method; Silver nanoparticles; Photocatalytic activity; Methyl orange
Acknowledgement: This work is a part of the activities of the FunGlass project. This project has received funding from the European Union Horizon 2020 Research and Innovation Program under Grant 739566. This work was also supported by the Grant VEGA 1/0431/18 of the Grant Agency of the Slovak Republic and the authors are grateful to the JECS Trust for funding (contract No. 2022301).