Structure and Stability of SnO2 Nanocrystals and Surface-Bound Water Species

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• 作者：Hsiu-Wen Wang ; David J. Wesolowski ; Thomas E. Proffen ; Lukas Vlcek ; Wei Wang ; Lawrence F. Allard ; Alexander I. Kolesnikov ; Mikhail Feygenson ; Lawrence M. Anovitz ; Rick L. Paul
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：May 8, 2013
• 年：2013
• 卷：135
• 期：18
• 页码：6885-6895
• 全文大小：802K
• 年卷期：v.135,no.18(May 8, 2013)
• ISSN：1520-5126

文摘

The structure of SnO₂ nanoparticles (avg. 5 nm) with a few layers of water on the surface has been elucidated by atomic pair distribution function (PDF) methods using in situ neutron total scattering data and molecular dynamics (MD) simulations. Analysis of PDF, neutron prompt gamma, and thermogravimetric data, coupled with MD-generated surface D₂O/OD configurations demonstrates that the minimum concentration of OD groups required to prevent rapid growth of nanoparticles during thermal dehydration corresponds to 0.7 monolayer coverage. Surface hydration layers not only stabilize the SnO₂ nanoparticles but also induce particle-size-dependent structural modifications and are likely to promote interfacial reactions through hydrogen bonds between adjacent particles. Upon heating/dehydration under vacuum above 250 掳C, nanoparticles start to grow with low activation energies, rapid increase of nanoparticle size, and a reduction in the a lattice dimension. This study underscores the value of neutron diffraction and prompt-gamma analysis, coupled with molecular modeling, in elucidating the influence of surface hydration on the structure and metastable persistence of oxide nanomaterials.