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.