title: Trimethylphosphine-Assisted Surface Fingerprinting of Metal Oxide Nanoparticle by (31)P Solid-State NMR: A Zinc Oxide Case Study.
abstract: Nano metal oxides are becoming widely used in industrial, commercial and personal products (semiconductors, optics, solar cells, catalysts, paints, cosmetics, sun-cream lotions, etc.). However, the relationship of surface features (exposed planes, defects and chemical functionalities) with physiochemical properties is not well studied primarily due to lack of a simple technique for their characterization. In this study, solid state (31)P MAS NMR is used to map surfaces on various ZnO samples with the assistance of trimethylphosphine (TMP) as a chemical probe. As similar to XRD giving structural information on a crystal, it is demonstrated that this new surface-fingerprint technique not only provides qualitative (chemical shift) but also quantitative (peak intensity) information on the concentration and distribution of cations and anions, oxygen vacancies and hydroxyl groups on various facets from a single deconvoluted (31)P NMR spectrum. On the basis of this technique, a new mechanism for photocatalytic •OH radical generation from direct surface-OH oxidation is revealed, which has important implications regarding the safety of using nano oxides in personal care products.
authors.affiliation: The Wolfson Catalysis Centre, Department of Chemistry, University of Oxford , Oxford OX1 3QR, U.K.
authors.forename: Yung-Kang
authors.initials: YK
authors.lastname: Peng
authors.affiliation: The Wolfson Catalysis Centre, Department of Chemistry, University of Oxford , Oxford OX1 3QR, U.K.
authors.forename: Lin
authors.initials: L
authors.lastname: Ye
authors.affiliation: The Wolfson Catalysis Centre, Department of Chemistry, University of Oxford , Oxford OX1 3QR, U.K.
authors.forename: Jin
authors.initials: J
authors.lastname: Qu
authors.affiliation: Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University , Shanghai 200433, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University , Shanghai 200433, PR China.
authors.forename: Yingyi
authors.initials: Y
authors.lastname: Fu
authors.affiliation: The Wolfson Catalysis Centre, Department of Chemistry, University of Oxford , Oxford OX1 3QR, U.K.
authors.forename: Ivo F
authors.initials: IF
authors.lastname: Teixeira
authors.affiliation: The Wolfson Catalysis Centre, Department of Chemistry, University of Oxford , Oxford OX1 3QR, U.K.
authors.forename: Ian James
authors.initials: IJ
authors.lastname: McPherson
authors.affiliation: Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University , Shanghai 200433, PR China.
authors.forename: Heyong
authors.initials: H
authors.lastname: He
authors.affiliation: The Wolfson Catalysis Centre, Department of Chemistry, University of Oxford , Oxford OX1 3QR, U.K.
authors.forename: Shik Chi Edman
authors.initials: SC
authors.lastname: Tsang