Iodine-Doped TiO2 Photocatalysts: Correlation between Band Structure and Mechanism

Abstract

Iodine-doped TiO2 powders (I-TiO2) prepared via hydrothermal treatment have absorption in the region of ultraviolet (UV) and visible light, and were used as a photocatalyst with irradiation of UV or visible light. The I-TiO2 powders were characterized by XRD, TEM, EDS, XPS, FTIR, and steady-state UV−vis diffuse reflectance spectra (DRS), and their photocatalytic activities were investigated based on the photodegradation of 4-chlorophenol (4-CP) in water. A higher photodegradation efficiency of 4-CP was observed for I-TiO2 under UV- and visible-light irradiation, when compared to the undoped TiO2. The transient behavior of the photogenerated charge carriers, such as trapped electrons (e−) and holes (h+), and the one-electron oxidation dynamics of substrates during UV or visible laser flash photolysis of undoped TiO2 and I-TiO2 powders were investigated using time-resolved diffuse reflectance (TDR) spectroscopy. The time evolution of transient signals indicated that the long-lived photogenerated h+ were for...