title: Shape Evolution of Metal Nanoparticles in Water Vapor Environment.
abstract: The structures of the metal nanoparticles are crucial for their catalytic activities. How to understand and even control the shape evolution of nanoparticles under reaction condition is a big challenge in heterogeneous catalysis. It has been proved that many reactive gases hold the capability of changing the structures and properties of metal nanoparticles. One interesting question is whether water vapor, such a ubiquitous environment, could induce the shape evolution of metal nanoparticles. So far this question has not received enough attention yet. In this work, we developed a model based on the density functional theory, the Wulff construction, and the Langmuir adsorption isotherm to explore the shape of metal nanoparticle at given temperature and water vapor pressure. By this model, we show clearly that water vapor could notably increase the fraction of (110) facets and decrease that of (111) facets for 3-8 nm Cu nanoparticles, which is perfectly consistent with the experimental observations. Further investigations indicate the water vapor has different effects on the different metal species (Cu, Au, Pt, and Pd). This work not only helps to understand the water vapor effect on the structures of metal nanoparticles but also proposes a simple but effective model to predict the shape of nanoparticles in certain environment.
authors.affiliation: Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201800, China.|Shanghai Science Research Center, Chinese Academy of Sciences , Shanghai 201204, China.
authors.forename: Beien
authors.initials: B
authors.lastname: Zhu
authors.affiliation: Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201800, China.|Shanghai Science Research Center, Chinese Academy of Sciences , Shanghai 201204, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201800, China.|Shanghai Science Research Center, Chinese Academy of Sciences , Shanghai 201204, China.
authors.forename: Chunlei
authors.initials: C
authors.lastname: Wang
authors.affiliation: Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201800, China.|Shanghai Science Research Center, Chinese Academy of Sciences , Shanghai 201204, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Gao
keywords: Wulff Construction; density functional theory; metal nanoparticle; water vapor