In situ X‐ray absorption spectroscopic studies of TiO2 photocatalytic active sites for degradation of trace CHCl3 in drinking water. (21st October 2021)

• Record Type: Journal Article
• Authors: Hsiung, T.-L.; Wei, L.-W.; Huang, H.-L.; Wang, H. Paul
• Is Part Of: Journal of synchrotron radiation. Volume 28:Part 6(2021)
• Page Start: 1839
• Page End: 1844
• Publication Date: 2021-10-21
• Subjects: TiO2 composite nanoparticles -- photocatalysis -- CHCl3 -- XANES -- photoactive sites; Synchrotron radiation -- Periodicals; Free electron lasers -- Periodicals; 539.73505
• DOI: 10.1107/S1600577521008973
• Languages: English
• ISSNs: 0909-0495

Abstract

Abstract : In this article, photoactive sites such as A1 (4969 eV), A2 (4971 eV) and A3 (4972 eV) in the nano, cluster and atomic dispersed TiO2 photocatalysts can be distinguished by in situ X‐ray absorption near‐edge structure spectroscopy. Notably, the A2 active species in the atomic dispersed Ti (Ti‐MCM‐41) may be responsible for about 95% of the accumulated photocatalytic degradation of trace CHCl3 in drinking water ( i.e. 7.2 p.p.m. CHCl3 gTiO2 −1 h −1 ), which may be useful for engineering capable TiO2 photocatalysts. Abstract : Toxic disinfection byproducts such as trihalomethanes ( e.g. CHCl3 ) are often found after chlorination of drinking water. It has been found that photocatalytic degradation of trace CHCl3 in drinking water generally lacks an expected relationship with the crystalline phase, band‐gap energy or the particle sizes of the TiO2 ‐based photocatalysts used such as nano TiO2 on SBA‐15 (Santa Barbara amorphous‐15), TiO2 clusters (TiO2 –SiO2 ) and atomic dispersed Ti [Ti‐MCM‐41 (Mobil Composition of Matter)]. To engineer capable TiO2 photocatalysts, a better understanding of their photoactive sites is of great importance and interest. Using in situ X‐ray absorption near‐edge structure (XANES) spectroscopy, the A1 (4969 eV), A2 (4971 eV) and A3 (4972 eV) sites in TiO2 can be distinguished as four‐, five‐ and six‐ coordinated Ti species, respectively. Notably, the A2 Ti sites that are the main photocatalytic species of TiO2 are shown to be accountable for about 95% of the photocatalytic degradation of trace CHCl3 in drinking water (7.2 p.p.m. CHCl3 gTiO2 −1 h −1 ). This work reveals that the A2 Ti species of a TiO2 ‐based photocatalyst are mainly responsible for the photocatalytic reactivity, especially in photocatalytic degradation of CHCl3 in drinking water.