Effect of milling speed on the precursor zinc acetylacetonate destined to obtain ZnO thin films

In this work, zinc oxide (ZnO) thin films were deposited on glass substrates by the ultrasonic spray pyrolysis technique, USP, the starting precursor (zinc acetylacetonate) was milled by planetary ball milling. The milling conditions were, 60 minutes and milling speed ranging from 300 to 600 rpm. The ball to power ratio was 7:1 in a tungsten carbide vessel. For depositing the ZnO thin films, a 0.2 M starting solution was prepared by dissolving the milled precursor in a mix of methanol, water, and acetic acid. Films were deposited at 400 and 450 °C with a time deposition of 6 minutes. These films were tested for measure the photocatalytic degradation of methylene blue (MB) dye under UV light irradiation. The effect of milling speed of the zinc precursor on the photocatalytic degradation has been studied in this work. Both Zn precursor powders and ZnO thin films were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). Thin films deposited at 400°C from a precursor milled at 300 rpm presented the maximum catalytic degradation, around 99%, after being exposed to UV radiation during 5 hr.