title: Peculiar and rapid photocatalytic degradation of tetrabromodiphenyl ethers over Ag/TiO2 induced by interaction between silver nanoparticles and bromine atoms in the target.
abstract: As a typical moderately-brominated diphenylethers, 2,2',4,4'-tetrabromodiphenyl ether (BDE47) is hardly debrominated by a conventional TiO2-mediated photocatalysis. However, its reductive debromination was rapid achieved over silver nanoparticle-loaded TiO2 (Ag/TiO2) in UV-irradiated anoxic acetonitrile-water within 13 min. An "Ag-promoted electron transfer and C-Br cleavage" concept was proposed based on experimental results and density functional theory calculations. Ag(0) exerted affinity interaction with bromine atoms, and the storing of electrons on Ag(0) increased the binding interaction, which elongated the C-Br bond of BDE47 and facilitated its cleavage. The initiating of the BDE47 debromination on Ag(0) required an induction period to enrich a critical amount of electrons, leading to a stronger driving force for both injecting electron to BDE47 and stretching the C-Br bond. Stronger photo-excitation, higher polar solvent, and a moderate Ag(0) load strengthened the interfacial electron transfer over Ag/TiO2, and thereby shortening the induction time and accelerating the BDE47 degradation.
authors.affiliation: College of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, PR China.
authors.forename: Ming
authors.initials: M
authors.lastname: Lei
authors.affiliation: College of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, PR China. Electronic address: nwang@hust.edu.cn.
authors.forename: Nan
authors.initials: N
authors.lastname: Wang
authors.affiliation: College of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, PR China.
authors.forename: Lihua
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, College of Chemistry and Materials Science, South-Central University for Nationalities, Wuhan, 430074, PR China.
authors.forename: Heqing
authors.initials: H
authors.lastname: Tang
mesh_terms: D001966:Bromine / Q000737:chemistry*; D002384:Catalysis; D055768:Halogenated Diphenyl Ethers / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry* / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D055768:Halogenated Diphenyl Ethers; C511295:2,2',4,4'-tetrabromodiphenyl ether; C009495:titanium dioxide; D012834:Silver; D014025:Titanium; D001966:Bromine
keywords: Induction time; Photocatalytic debromination; Polybromodiphenyl ether; Silver nanoparticle; Titanium dioxide