Antimicrobial Activity of Pd-Doped ZnO Sol-Gel-Derived Films

Palladium doped ZnO was prepared by the sol-gel and dip-coating techniques, starting with zinc acetate and palladium chloride as precursors, followed by its hydrolysis in methanol. Acetic acid was incorporated to adjust pH, as well as acetylacetonate and monoehtylamine as stabilizers. The sol was later dipped 3 times in silica substrates. Structural, morphological, and antimicrobial properties of the films were investigated for three palladium contents (1.0, 2.5, and 5mol %). X-ray diffraction (XRD) showed that the films have a hexagonal structure after been annealed at 500 degrees C. X-ray photoelectron Spectroscope (XPS) showed that Pd is present in its oxidized form. Atomic force microscopy (AFM) from films showed a crack free and smooth surface (Ra= 18nm), composed of cross-linked particles. The synthesized films presented antibacterial activity against Escherichia coli and Pseudomona aeruginosa. It was observed that the higher Pd content (5mol %) presents the higher antimicrobial ratio, 64.07%, for the E.coli, whereas for the P.aeruginosa, the lower Pd content (1mol %), shows the higher antimicrobial ratio, 76.43%.