Influence of substrate on the hydrophilicity and photocatalytic properties of TiO2 nano-layers

Abstract

The influence of substrate materials on the hydrophilicity and photocatalytic properties of TiO2 thin films, prepared by the sol–gel spray pyrolysis method is investigated. In this regard, thin gold or copper films on glass, Ag-ion-exchanged glass and bare glass were used as substrates for TiO2 thin films. It is found that in comparison to other samples, a TiO2 thin film on the copper/glass substrate demonstrates the most efficient hydrophilicity property, while gold/glass substrate is the best in regards to photocatalytic behavior. The smaller band gap, larger grain size and roughness of the thin films show better photocatalyticity. In our case, we observed that, for gold/glass substrate a more condensed film causes a higher recombination rate of electron–hole pairs, which in turn decreases the hydrophilicity property of the samples.