Photo-Induced Bismuth Single Atoms on TiO<sub>2</sub> for Highly Efficient Photocatalytic Defluorination of Perfluorooctanoic Acid: Ionization of the C–F Bond
Xiaoqing Liu, Kedong Gong, Xiaoguang Duan, Wei Wei, Tao Wang, Zhijie Chen, Liwu Zhang, Bing‐Jie Ni
Abstract
Single-atom catalysts (SACs), as a newcomer in the field of nanocatalysis, have gained intensive interest due to their excellent activities. In this study, single bismuth (Bi) atom-decorated TiO 2 catalysts (N-Bi/TiO 2 ) are synthesized by the simple UV irradiation method using Bi(NO 3 ) 3 as the precursor. Characterizations confirmed that single Bi atoms were homogeneously dispersed on the surface of TiO 2 . BiOCl nanoclusters were formed on TiO 2 (Cl-Bi/TiO 2 ) when BiCl 3 was used as the precursor. Both N-Bi/TiO 2 and Cl-Bi/TiO 2 demonstrated excellent performance for the defluorination of perfluorooctanoic acid (PFOA) under a UV 254 nm irradiation. A deep defluorination of PFOA was obtained by N-Bi/TiO 2 with a defluorination ratio of 85% under a xenon lamp irradiation for 4 h. Moreover, a relatively high defluorination of 65% for PFOA over N-10Bi/TiO 2 remained after recycling use for 4 times. Cl-10Bi/TiO 2 also demonstrated a good performance for the defluorination of PFOA under xenon lamp irradiation, with an obtained defluorination ratio of 76% for 4 h. The diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) demonstrated that Bi single atoms induced the ionization of the C–F bond of PFOA, leading to the deep defluorination of PFOA. Density-functional theory (DFT) and finite-difference time-domain (FDTD) calculations further revealed the ionization of PFOA on N-10Bi/TiO 2, which is due to the high electric field concentration near Bi single atoms. These findings provide a new approach for manipulating the photocatalytic activity of TiO 2 -based composites and broaden the knowledge regarding the heterogeneous activation of the C–F bond.