Nanoscale engineering of Sr-doped ZnO nanorods/CuO nanocomposites for the photocatalytic treatment of methylene blue pollutant

This study investigates the effect of Sr doping on the physical and photocatalytic properties of ZnO nanorods/CuO nanocomposites. Various techniques were applied to understand how Sr doping modifies these films. SEM analysis showed that ZnO and CuO formed structures such as nanorods or nanowires. Sr-doped samples exhibited increased aggregation compared to undoped composites, with Sr doping levels of 2.0 % and 4.0 % leading to more pronounced morphological changes. AFM measurements showed an increase in average roughness from 70.53 nm to 111.83 nm with higher Sr doping levels. XRD analysis showed that the crystallite sizes decreased from 36.20 nm for undoped samples to 31.55 nm and 29.90 nm with 2.0 % and 4.0 % Sr doping, respectively. FTIR Spectroscopy provided insights into the chemical bonding changes induced by Sr doping. The bandgap analysis revealed that Sr doping in the ZnO/CuO nanocomposites enhanced the bandgap energy, with the value increasing from 2.41 eV in the undoped sample to 3.61 eV at 4.0 % Sr doping. Electrical conductivity measurements showed a decrease in total resistance values as the Sr doping ratio increased. The contact resistance values increased from 3.13 × 109 Ω in the un-doped samples to 3.22 × 108 Ω in the 4.0 % Sr-doped films. It was observed that 2.0 % Sr doping increased the photocatalytic degradation of the ZnO nanorods/CuO nanocomposite films, whereas 4.0 % Sr doping decreased this effect. Thus, the dynamic evaluation of the catalytic performance with TOF yields values of 0.176 and 0.184 for ZnO nanorods/CuO nanocomposites films and ZnO nanorods/CuO:Sr (2.0 %), respectively.