Effect of sulfate ions for sol–gel synthesis of titania photocatalyst

Abstract We have found that the use of sulfuric acid in the peptization process of sol–gel method produced SO 4 2− -incorporated TiO 2 which is mechanically strong by firing at low temperature such as 200°C. The synthesized TiO 2 has larger specific surface area and retards the phase transition from anatase to rutile compared with that prepared from the peptization with nitric acid. The S-content of the TiO 2 fired at 200°C was 1.52 wt.%; the value has a maximum of 2.74 wt.% at 400°C. The XPS measurements indicate that S exists mainly as SO 4 2− . The TiO 2 fired at 400°C showed the highest photocatalytic activity for ethylene degradation. Especially, we would like to emphasize the TiO 2 sintered at 200°C because they are extremely hard in spite of such a low sintering temperature. This photocatalyst may provide a great opportunity for extensive applications as self-supporting membranes.