title: Identification of different oxygen species in oxide nanostructures with (17)O solid-state NMR spectroscopy.
abstract: Nanostructured oxides find multiple uses in a diverse range of applications including catalysis, energy storage, and environmental management, their higher surface areas, and, in some cases, electronic properties resulting in different physical properties from their bulk counterparts. Developing structure-property relations for these materials requires a determination of surface and subsurface structure. Although microscopy plays a critical role owing to the fact that the volumes sampled by such techniques may not be representative of the whole sample, complementary characterization methods are urgently required. We develop a simple nuclear magnetic resonance (NMR) strategy to detect the first few layers of a nanomaterial, demonstrating the approach with technologically relevant ceria nanoparticles. We show that the (17)O resonances arising from the first to third surface layer oxygen ions, hydroxyl sites, and oxygen species near vacancies can be distinguished from the oxygen ions in the bulk, with higher-frequency (17)O chemical shifts being observed for the lower coordinated surface sites. H2 (17)O can be used to selectively enrich surface sites, allowing only these particular active sites to be monitored in a chemical process. (17)O NMR spectra of thermally treated nanosized ceria clearly show how different oxygen species interconvert at elevated temperature. Density functional theory calculations confirm the assignments and reveal a strong dependence of chemical shift on the nature of the surface. These results open up new strategies for characterizing nanostructured oxides and their applications.
authors.affiliation: Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Wang
authors.affiliation: Key Laboratory for Advanced Materials, Centre for Computational Chemistry and Research Institute of Industrial Catalysis, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China.
authors.forename: Xin-Ping
authors.initials: XP
authors.lastname: Wu
authors.affiliation: Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Sujuan
authors.initials: S
authors.lastname: Zheng
authors.affiliation: Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.affiliation: Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Li
authors.initials: L
authors.lastname: Shen
authors.affiliation: Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Yuxian
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Nianhua
authors.initials: N
authors.lastname: Xue
authors.affiliation: Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Guo
authors.affiliation: Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Weixin
authors.initials: W
authors.lastname: Huang
authors.affiliation: National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310-3706, USA.
authors.forename: Zhehong
authors.initials: Z
authors.lastname: Gan
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK. ; Department of Chemistry and Stephenson Institute for Renewable Energy, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Blanc
authors.affiliation: High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China.
authors.forename: Zhiwu
authors.initials: Z
authors.lastname: Yu
authors.affiliation: Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Xiaokang
authors.initials: X
authors.lastname: Ke
authors.affiliation: Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Weiping
authors.initials: W
authors.lastname: Ding
authors.affiliation: Key Laboratory for Advanced Materials, Centre for Computational Chemistry and Research Institute of Industrial Catalysis, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China.
authors.forename: Xue-Qing
authors.initials: XQ
authors.lastname: Gong
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK. ; Department of Chemistry, Stony Brook University, Stony Brook, NY 11974-3400, USA.
authors.forename: Clare P
authors.initials: CP
authors.lastname: Grey
authors.affiliation: Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Luming
authors.initials: L
authors.lastname: Peng