title: Highly Dense Isolated Metal Atom Catalytic Sites: Dynamic Formation and In Situ Observations.
abstract: Atomically dispersed noble-metal catalysts with highly dense active sites are promising materials with which to maximise metal efficiency and to enhance catalytic performance; however, their fabrication remains challenging because metal atoms are prone to sintering, especially at a high metal loading. A dynamic process of formation of isolated metal atom catalytic sites on the surface of the support, which was achieved starting from silver nanoparticles by using a thermal surface-mediated diffusion method, was observed directly by using in situ electron microscopy and in situ synchrotron X-ray diffraction. A combination of electron microscopy images with X-ray absorption spectra demonstrated that the silver atoms were anchored on five-fold oxygen-terminated cavities on the surface of the support to form highly dense isolated metal active sites, leading to excellent reactivity in catalytic oxidation at low temperature. This work provides a general strategy for designing atomically dispersed noble-metal catalysts with highly dense active sites.
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution & Prevention (LAP3), Department of Environmental Science & Engineering, Fudan University, 220 Handan Road, 200433 Shanghai (P. R. China).
authors.forename: Yaxin
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Center for Electron Nanoscopy, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark).
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kasama
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution & Prevention (LAP3), Department of Environmental Science & Engineering, Fudan University, 220 Handan Road, 200433 Shanghai (P. R. China).
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution & Prevention (LAP3), Department of Environmental Science & Engineering, Fudan University, 220 Handan Road, 200433 Shanghai (P. R. China).
authors.forename: Pingping
authors.initials: P
authors.lastname: Hu
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution & Prevention (LAP3), Department of Environmental Science & Engineering, Fudan University, 220 Handan Road, 200433 Shanghai (P. R. China).
authors.forename: Jianmin
authors.initials: J
authors.lastname: Chen
authors.affiliation: Center for Electron Nanoscopy, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark). xilicen@dtu.dk.
authors.forename: Xi
authors.initials: X
authors.lastname: Liu
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution & Prevention (LAP3), Department of Environmental Science & Engineering, Fudan University, 220 Handan Road, 200433 Shanghai (P. R. China). tangxf@fudan.edu.cn.
authors.forename: Xingfu
authors.initials: X
authors.lastname: Tang
keywords: X-ray diffraction; electron microscopy; heterogeneous catalysis; surface analysis; surface chemistry