ZnO semiconductors obtained by slip casting: Application and reuse in photocatalysis

• Published in: International journal of applied ceramic technology 2021-05, Vol.18 (3), p.622-630
• Main Authors: Domingos, Gustavo H. S., Ruellas, Thamara M. O., Peçanha, Luiz O. O., Malafatti, João O. D., Paris, Elaine C., Maestrelli, Sylma C., Giraldi, Tania R.
• Format: Article
• Language: English
• Subjects: Catalytic activity; Crystal structure; Degradation; Dyes; Grain size; Heat treatment; Organic matter; Photocatalysis; Porosity; Reuse; Rhodamine; Rhodamine B; Semiconductors; Slip casting; Theoretical density; Wurtzite; Zinc oxide; ZnO
• ISSN: 1546-542X; 1744-7402
• DOI: 10.1111/ijac.13698

This work described the acquisition of immobilized ZnO semiconductors using the slip casting technique, for application as reusable photocatalysts in the degradation of Rhodamine B. The influence of the heat treatment temperature (800°C, 900°C, and 1000°C) on the physical, thermal, microstructural, and photocatalytic properties was investigated. All samples presented the wurtzite crystal structure, and the surface was completely absent of organic matter residues. The samples presented band gap values around 3.2 eV. The ones heat treated at 800°C showed lower density (3.40 g/cm3, corresponding to 60% of the ZnO theoretical density), smaller average grain size, in addition to higher apparent porosity (around 40%). These characteristics provide better photocatalytic activity to the sample heat treated at 800°C, since it promoted 92.2% dye degradation, while samples heat treated at 900°C and 1000°C promoted 81.8% and 54.2% dye degradation, respectively. The integrity of all samples was maintained after the photocatalytic tests. Thus, the reuse capability of the sample with the best photocatalytic performance, that is, the sample heat treated at 800°C, was evaluated in six cycles of photocatalysis. The sample proved to be reusable, promoting degradation of practically 100% of the dye after the third cycle of reuse.