Role of Mn Doping in Improving the Hydrophobic Property of ZnO Coating on Aluminum Substrate

Due to their interesting physical and structural characteristics, zinc oxide nanostructures are one of the most commonly used materials to elaborate hydrophobic or superhydrophobic surfaces. In this work, undoped and Mn-doped ZnO thin films are prepared by the thermal oxidation of electrodeposited zinc thin layers on aluminum substrates. Structural analysis by X-ray powder diffraction and Raman spectroscopy shows the formation of ZnO mico-nanostructures, and no secondary phase linked to Mn is detected. Energy dispersive X-ray spectroscopy analysis confirms the presence of zinc and oxygen, with no Mn element detected in the doped samples. However, at high Mn concentrations, Raman spectroscopy shows the main ZnO modes with a decrease in their intensities and the appearance of new modes with increasing Mn concentration, indicating that the structural quality is slightly degraded. The formation of the deformed flower-shaped structures covered with spherical ZnO nanostructures leads to the hydrophobicity of the ZnO coating, and doping with a small Mn concentration improves this last property.