Fabrication of double cation (Sn + Mg) activated ZnO thin films for environmental and health care applications

Undoped and Sn + Mg doped ZnO thin films were deposited onto glass substrates using a nebulizer spray technique. The optical, structural, photoluminescence, morphological, photocatalytic and antibacterial properties were investigated for various doping levels (2, 4, 6, 8 and 10 at.%) of Mg and constant doping level (6 at.%) of Sn. The XRD studies show that all the films are polycrystalline ZnO with hexagonal wurtzite structure and the size of the crystallites is in the range of 48–71 nm. The optical transmittance in the visible region increases desirably (≈90%) after doping. Significant enhancement in the optical band gap is observed with Mg doping. ZnO:Sn:Mg thin film sample with 6 at.% of Mg doping level exhibits good photocatalytic and antibacterial efficiencies. The reduction in grain size due to doping as observed from SEM images plays an important role in enhancing the photocatalytic and antibacterial efficiencies of ZnO:Sn:Mg films. The structural, optical and photoluminescence results corroborate well with the discussions on the photocatalytic and antibacterial efficiencies of the ZnO:Sn:Mg films.