Influence of hole-scavenger and different withdrawn speeds on photocatalytic activity of Co3O4 thin films under sunlight irradiation

Cobalt oxide (Co3O4) thin films with environmentally friendly properties and high photocatalytic activity under sunlight were employed in this work as a beneficial and cost-effective material. This research provides a novel study for cobalt oxide (Co3O4) thin films that were dip-coated on pretreated glass substrates at different withdrawn speeds. The structure, surface morphology, surface roughness, and optical properties were studied and discussed. The photocatalytic performance of cobalt oxide thin films was investigated via degradation of blue methylene (BM) under sunlight irradiation. In addition, the effect of hole-scavengers on the feed of conduction band by electrons was investigated. 5 mm/s withdrawn speed achieved high photocatalytic efficiency at 78% correspond to (220) growth orientation, 39.7 nm of crystal size, 2.01 eV of band gap energy, and 55 nm surface roughness. At the same withdrawn speed, BM degradation was improved by 9.47, 17.57, and 20.09% for Co3O4 thin films with the presence of hole-scavengers Octan-1-ol, EDTA, and H2O2, respectively. All the films show hydrophilic surface properties as the contact angle was under 60°. Emphasized the potential for application to various types of organic contaminants from various wastewater sources under sunlight irradiations.