EFFECTS OF FIRING TEMPERATURE ON PHOTOCATALYTIC AND PHOTOELECTROCATALYTIC PROPERTIES OF TIO2

This paper describes studies of the effect of firing temperature on th e photocatalytic and photoelectrocatalytic degradation of formic acid (HCOOH) using ultraviolet (UV) illuminated TiO2 thin films. Other vari ables, such as the potential applied [versus saturated calomel electro de (SCE)] to the film and the number of layers of film applied to the support were examined to determine optimum conditions for degradation. The transformation of TiO2 from anatase to rutile in the thin films w as significantly retarded by placing the films on SnO2-covered glass. Results indicate that films fired at 500 degrees C showed the best eff iciency for pure photocatalytic degradation, while films fired at 600 degrees C had the best efficiency for the photoelectrocatalytic degrad ation of HCOOH. The efficiency of these photoelectrocatalytic reaction s increased with increasing potential until 2 V (versus SCE) was obtai ned. A film with one layer (0.27 mu m thickness) showed the maximum de gradation of HCOOH for photoelectrocatalytic reactions at 2 V (versus SCE), as no further increase in the rate of degradation of HCOOH was o btained by using thicker films.