Effect of Pd as Dopant on Photocatalytic Microbial Inactivation of TiO2 Thin Film

TiO2 thin film has excellent photocatalyst properties. Because of that it has various applications such as air clean-up, water purification, anti-bacteria, antifogging coating, gas sensors and so on[1,2].When TiO2 is exposed to light, by the absorption of ultra band gap light it can be excited and generated electron/hole (e-/h+) pairs in the conduction/valence band region. The electron/hole pairs move to the surface and convert oxygen to superoxide radicals (O20) by reaction with the electrons and H2O molecules to OH0 radicals by reaction with the holes. Then this radicals can participate in the photodegradation process and oxidize the pollutant [3,4].In spite of beneficial applications, there are some limitations for using of this semiconductor. One of them is the necessity of photo activation of this layer with UV illumination. Another is charge carrier recombination that result in decreasing of photocatalytic activity. Some metals such as iron, cobalt and chromium have been used as dopants to overcome these limitations. Presence of these metals in the film decease the recombination of electron/hole and act as charge separator. Excited electrons are transferred from the conduction band of the semiconductor to the metal, thus preventing recombination [5].This film had been prepared by different kinds of deposition techniques such as sputtering, chemical vapor deposition, sol gel processing and so on. Sol gel techniques have an ability to produce homogeneous layer at a molecular level, ease and versatility of processing and lower crystallization temperature [1,4].In this current study we used Palladium for improving antibacterial properties of TiO2 thin film. We prepared the TiO2 thin film loaded with Pd, using particulate sol gel route on stainless steel 316 substrates then Evaluation of antibacterial activity of coating against S.aureus bacteria was examined by static antibacterial tests.