Enhanced photocatalytic activity of ZnO thin films with labyrinth-like architecture by thermal-shock-fluorination on novel zinc-coated copper substrate for sustainable applications

While ZnO nanoparticles have been regarded as promising photocatalysts for addressing organic pollutants in water, they still pose several challenges, such as low activity under UV–visible illumination and difficulties in the recovery of catalytic powder. To overcome these limitations, in this work, thin films composed of surface-modified ZnO nanoparticles for the first time with labyrinth-like architecture were successfully immobilized on a unique zinc-electroplated copper substrate by using a simple sol–gel spin coating technique followed by our thermal-shock-fluorination method (at 400, 500 or 600 °C). The degradation of several organic dyes, including cationic and anionic dyes, under UVA light and visible light irradiation was used to assess their photocatalytic activity. The results demonstrate that the synergistic effect of fluorination and thermal shock greatly enhanced the photocatalytic performance of our samples. Specifically, this treatment significantly altered the surface texture of ZnO thin films by creating labyrinth-like architecture with surface chain walls and oxygen vacancies, resulting in enhanced activity. Furthermore, by electro-coating Cu plates with oxidized zinc layers, we successfully obtained a thermally and mechanically robust substrate that effectively promotes the attachment of ZnO nanoparticles, improving the applicability of our photocatalysts under harsh conditions as well as their recovery and reuse.

Graphical Abstract