The effect of Mg doping on structural and catalytic removal of malachite green using ZnO thin films fabrication by cost effective home-made spray pyrolysis technique

This study investigates the morphological and photocatalytic properties of pristine and Mg-doped ZnO (MZN) thin films, prepared using a simple and low-cost spray pyrolysis method at an optimal substrate temperature of 300 ± 5°C. The Mg/Zn atomic ratio varied between 3 %, 5 %, and 7 %. X-ray diffraction analysis confirmed the hexagonal wurtzite crystal structure, with no additional phases observed. Morphological studies revealed well-defined rootstock-like structures for the 7 % MZN thin film. UV-Vis spectrometry showed a shift in the absorption peak to lower wavelengths, resulting in an increased optical band gap with higher dopant concentrations. AFM analysis indicated increased roughness for the 7 % MZN film, which positively impacted dye removal efficiency. Photocatalytic degradation of malachite green (MG) dye under UV light revealed 92.73 % dye degradation in 80 min for the 7 % MZN thin film. The enhanced photocatalytic activity is attributed to the 2D root morphology, increased surface roughness, and optimal band gap of the 7 % MZN thin films. These findings highlight the potential of metal oxide thin films for dye removal applications.