title: Microbial synthesis of Pd/Fe3O4, Au/Fe3O4 and PdAu/Fe3O4 nanocomposites for catalytic reduction of nitroaromatic compounds.
abstract: Magnetically recoverable noble metal nanoparticles are promising catalysts for chemical reactions. However, the chemical synthesis of these nanocatalysts generally causes environmental concern due to usage of toxic chemicals under extreme conditions. Here, Pd/Fe3O4, Au/Fe3O4 and PdAu/Fe3O4 nanocomposites are biosynthesized under ambient and physiological conditions by Shewanella oneidensis MR-1. Microbial cells firstly transform akaganeite into magnetite, which then serves as support for the further synthesis of Pd, Au and PdAu nanoparticles from respective precursor salts. Surface-bound cellular components and exopolysaccharides not only function as shape-directing agent to convert some Fe3O4 nanoparticles to nanorods, but also participate in the formation of PdAu alloy nanoparticles on magnetite. All these three kinds of magnetic nanocomposites can catalyze the reduction of 4-nitrophenol and some other nitroaromatic compounds by NaBH4. PdAu/Fe3O4 demonstrates higher catalytic activity than Pd/Fe3O4 and Au/Fe3O4. Moreover, the magnetic nanocomposites can be easily recovered through magnetic decantation after catalysis reaction. PdAu/Fe3O4 can be reused in at least eight successive cycles of 4-nitrophenol reduction. The biosynthesis approach presented here does not require harmful agents or rigorous conditions and thus provides facile and environmentally benign choice for the preparation of magnetic noble metal nanocatalysts.
authors: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors: Ya
authors: Y
authors: Tuo
authors: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors: Guangfei
authors: G
authors: Liu
authors: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors: Bin
authors: B
authors: Dong
authors: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors: Jiti
authors: J
authors: Zhou
authors: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China.
authors: Aijie
authors: A
authors: Wang
authors: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors: Jing
authors: J
authors: Wang
authors: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors: Ruofei
authors: R
authors: Jin
authors: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors: Hong
authors: H
authors: Lv
authors: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors: Zeou
authors: Z
authors: Dou
authors: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors: Wenyu
authors: W
authors: Huang
mesh_terms: D000497:Alloys; D002384:Catalysis; D018360:Crystallography, X-Ray; D005290:Ferric Compounds / Q000378:metabolism*; D006046:Gold / Q000378:metabolism*; D006841:Hydrocarbons, Aromatic / Q000378:metabolism*; D007700:Kinetics; D060328:Magnetic Phenomena; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D017672:Nitrogen Compounds / Q000378:metabolism*; D009596:Nitrophenols / Q000378:metabolism; D010084:Oxidation-Reduction; D010165:Palladium / Q000378:metabolism*; D056951:Photoelectron Spectroscopy; D020592:Shewanella / Q000378:metabolism*
chemical_list: D000497:Alloys; D005290:Ferric Compounds; D006841:Hydrocarbons, Aromatic; D017672:Nitrogen Compounds; D009596:Nitrophenols; C000499:ferric oxide; D010165:Palladium; D006046:Gold; C024836:4-nitrophenol