During the work of this thesis the doped powdered photocatalysts based on the well-known photocataysts TiO2 and ZnO are developed at the Institute for Materials Science and Nanotechnology. Those catalytic nanoparticles are tested for the degradation of environmental pollutants in water, such as dyes and antibiotics. The photocatalytic nanoparticles are synthesized through chemical methods and tested for their activity with Methylene Blue (MB) as dye and Ciprofloxacin (CIP) as an antibiotic. Afterwards the catalysts were immobilized via the sol-gel route on substrates by dip-coating. The coated samples were subjected several methods for analysing the photocatalytic activity and for characterizing the coating layers. To characterize the morphology and stability, the 'scratch-test' was applied and the scratched coatings were characterized by Scanning Electron Microscopy (SEM).