Visible light-induced photocatalytic oxidation of 4-chlorophenol and dichloroacetate in nitrided Pt-TiO2 aqueous suspensions

This article reports the effect of nitridation treatment of TiO2 and Pt-doped TiO2 (Pt-TiO2) photocatalyst and assesses their performance as a visible light-induced photocatalyt for the degradation of 4-chlorophenol (4-CP) and dichloroacetate (DCA). Nitridation treatment changed the physicochemical properties of TiO2 and Pt-TiO2. The primary particle size of nitrided samples, n-TiO2 and n-Pt-TiO2, was slightly smaller than that of untreated samples. Surface area was increased more than two times after nitridation treatment. Thermal phase transformation (anatase to rutile) was retarded by the nitridation treatment. The visible light absorption of n-Pt-TiO2 was more extended than that of Pt-TiO2 and Pt(II)/Pt(IV) ratio in n-Pt-TiO2 was lower than that in Pt-TiO2. Enhanced photocatalytic activities of nitrided samples were observed for 4-CP degradation under UV and visible irradiation. However, the enhancement effect of nitridation treatment was not observed under visible irradiation for DCA degradation. Photocatalytic activity was restrictively enhanced and significantly affected by the kind of substrates.