title: Atomic scale observation of oxygen delivery during silver-oxygen nanoparticle catalysed oxidation of carbon nanotubes.
abstract: To probe the nature of metal-catalysed processes and to design better metal-based catalysts, atomic scale understanding of catalytic processes is highly desirable. Here we use aberration-corrected environmental transmission electron microscopy to investigate the atomic scale processes of silver-based nanoparticles, which catalyse the oxidation of multi-wall carbon nanotubes. A direct semi-quantitative estimate of the oxidized carbon atoms by silver-based nanoparticles is achieved. A mechanism similar to the Mars-van Krevelen process is invoked to explain the catalytic oxidation process. Theoretical calculations, together with the experimental data, suggest that the oxygen molecules dissociate on the surface of silver nanoparticles and diffuse through the silver nanoparticles to reach the silver/carbon interfaces and subsequently oxidize the carbon. The lattice distortion caused by oxygen concentration gradient within the silver nanoparticles provides the direct evidence for oxygen diffusion. Such direct observation of atomic scale dynamics provides an important general methodology for investigations of catalytic processes.
authors.affiliation: LeRoy Eyring Center for Solid State Science, Arizona State University, Tempe, Arizona 85287, USA.|Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, Beijing Key Laboratory of Bio-inspired Energy Materials and Devices, School of Chemistry and Environment, Beihang University, Beijing 100191, China.
authors.forename: Yonghai
authors.initials: Y
authors.lastname: Yue
authors.affiliation: School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, USA.
authors.forename: Datong
authors.initials: D
authors.lastname: Yuchi
authors.affiliation: Materials and Energy, Beijing Computational Science Research Center, Beijing 100193, China.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Guan
authors.affiliation: School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, USA.
authors.forename: Jia
authors.initials: J
authors.lastname: Xu
authors.affiliation: Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, Beijing Key Laboratory of Bio-inspired Energy Materials and Devices, School of Chemistry and Environment, Beihang University, Beijing 100191, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Guo
authors.affiliation: Department of Physics, Arizona State University, Tempe, Arizona 85287, USA.
authors.forename: Jingyue
authors.initials: J
authors.lastname: Liu