Photocatalytic and anti-bacterial activity of Y3+ doped ZnO thin films deposited by simplified spray pyrolysis technique

The present study used a simplified spray pyrolysis technique to successfully deposit pure ZnO and yttrium-doped ZnO (YZO) thin films with 2, 4 and 6 at. % of Y concentrations on glass substrates under ambient conditions. The impact of yttrium incorporation on the films' morphological, optical, structural, photocatalytic, and antibacterial characteristics was thoroughly investigated. The substitution of Y 3+ into the ZnO lattice was demonstrated by XRD analysis, which verified that all films crystallized in the hexagonal wurtzite phase without secondary Y-containing impurities. Defect-induced band tailing was confirmed by optical measurements, which revealed higher Urbach energies, decreased band gap, and increased visible absorption with increasing dopant concentration. Significant morphological evolution was shown by SEM and TEM results, displaying a distinctive tetrapod chain-like structure with a larger surface area. Due to improved charge separation and defect-assisted ROS generation, photocatalytic degradation of methylene blue showed that the 4 at. % YZO film had the highest degradation efficiency. Antibacterial tests against E. coli , Klebsiella pneumoniae , Staphylococcus aureus , and Bacillus subtilis further validated the YZO samples' superior performance. The results obtained from structural, optical, photocatalytic, and antibacterial studies highlighted that the 4 at. % of YZO thin film can be suitable for environmental applications. • Pure and Y-doped ZnO thin films were deposited by ambient spray pyrolysis. • Y 3+ incorporation induced lattice defects and band gap narrowing. • Defect-induced band tailing enhanced visible-light absorption. • Y doping produced tetrapod chain-like nanostructures with larger surface area. • Highest photocatalytic methylene blue degradation occurred at 4 at. % YZO. • YZO films exhibited enhanced antibacterial activity against Gram-positive and Gram-negative bacteria.