Correlation of Photodegradation Efficiency with Surface Potential of Silver-TiO₂ Nanocomposite Thin Films

The present work focuses on photocatalytic performance of Ag-TiO 2 systems. Nanocrystalline thin films of TiO 2 -and Ag-doped TiO 2 are grown by sol–gel method, followed by spin-coating technique on Si ⟨100⟩ surface. The crystallinity and crystal size were measured from X-ray diffraction and transmission electron microscopy studies. Lateral distribution of work function (WF) was examined through contact potential difference measurement done by scanning Kelvin probe microscopy. Local WFs of Ag-TiO 2 thin films were found to be smaller than that of TiO 2, and the minimum WF expected from the polynomial curve fitting was that of pure Ag. The photocatalytic efficiency of these thin films is estimated from photodegradation of methyl orange analyzed by UV–vis spectrophotometer. The photodegradation efficiency of Ag-TiO 2 nanocrystalline thin films increases up to a certain dopant concentration of silver, beyond which it decreases. The changes in the photodegradation efficiency of these films are correlated with variation in contact potential difference.