Effect of Doping ZnO Films with Cu on the Decoloration of Methylene Blue by Photocatalysis

This work presents results from examining thin films of Zinc Oxide (ZnO) and Copper-doped Zinc Oxide (ZnO:Cu) as photocatalysts for degrading Methylene Blue (MB) in aqueous solutions. Films were deposited on soda-lime glass substrates at temperatures from 450 to 525°C and thicknesses from 200 to 1370 nm using the Pneumatic Pyrolytic Spray technique. Doping with Cu aimed to enhance photocatalytic efficiency. Structural, optical, morphological and compositional properties were analyzed using X-ray Diffraction (XRD), UV-Vis Spectrophotometry, Scanning Electron Microscopy (SEM), and secondary ion mass spectrometry (SIMS). ZnO and Cu-doped ZnO films displayed a hexagonal wurtzite-like structure and good homogeneity. Photocatalytic degradation of MB was tested under UV light at 254 nm for 5 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$h$</tex>, obtaining a degradation of 99.97% for Cu-doped ZnO films compared to 90% for pure ZnO. The study carried out in this work confirms the efficacy of Cu-doped ZnO films for degradation of organic contaminants in water by low-cost deposition techniques.