Effect of Substrate Sodium Content on Crystallization and Photocatalytic Activity of TiO₂Films Prepared by DC Magnetron Sputtering

Abstract

The effect of sodium content of the glass support on the crystallinity of sputtered<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="E1"><mml:mrow><mml:msub><mml:mrow><mml:mtext>TiO</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>films and photocatalytic breakdown of ethanol has been studied. It was found that the activity of the as-deposited (amorphous) films does not depend on the type of support used. The chemical composition of the glass support does influence the activity of annealed films. When using soda-lime glass support sodium diffuses into the film upon annealing, suppressing anatase crystallization and decreasing its photocatalytic activity. To decrease the influence of sodium, soda-lime glass coated with an e-beam evaporated<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="E2"><mml:mrow><mml:msub><mml:mrow><mml:mtext>SiO</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>barrier layer was used with good result. A reduced sodium concentration in the film leads to well crystallized anatase after annealing. An increased photocatalytic activity was observed for these films.