The Effect of Geometrical Characteristics of Tio2 Nanotube Arrays on the Photocatalytic Degradation of Organic Pollutants

Abstract

Highly ordered TiO2 nanotube arrays (TNAs) were fabricated by electrochemical anodization under varying durations and voltages. The effects of the anodizing parameters on geometrical properties were investigated. The results showed that as the anodizing time increased from 15 to 45 min, the length of the nanotubes increased, but there was no change in their diameter, hence the surface area increased while the open porosity did not change. When the effect of the anodizing voltage was examined, it was observed that both the length and diameter increased as the voltage increased from 15 to 45 V. Thus, a significant increase in open porosity and surface area was observed. The UV-Vis spectrophotometer was used to evaluate the effects of all geometrical characteristics on the photodegradation of methylene blue (MB). The results showed that the anodizing parameters were highly effective on the photocatalytic degradation of MB. With the decrease of the anodizing voltage, the photocatalytic activity increased because of the geometrical characteristics of TNAs. Accordingly, TNAs with the surface area of 25 m(2)/g and the open porosity of 35% obtained by anodizing for 45 min at 15 V showed the highest photocatalytic activity with a degradation efficiency of similar to 81% in 7 h.