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Séminaire de l’équipe « Oxydes en basses dimensions » - INSP

From colloids to functional materials : different wet-chemistry synthesis routes to metal oxide nanostructures (and beyond…)

Sylvia Gross, Università degli Studi di Padova (Italia)
Lundi 9 décembre 2013 à 14 h - INSP - 4 place Jussieu - 75252 PARIS Cedex 05 - Barre 22-32, 2e étage, salle 201

Abstract
As the historical book by Ostwald [1] already pointed out, colloids are a neglected dimension of matter which however catalyses increasing attention due to the outstanding potential they offer, also from a synthetic point of view, as building blocks for the assembly of different kind of nanostructured functional materials. In fact the colloidal domain discloses exciting perspectives in the tailored synthesis of new materials.[2] The control on morphological, compositional and microstructural features represents however a primary requirement to get the desired properties, and a fascinating playground for inorganic chemists. In this habit, sustainable and easy wet chemistry colloidal routes are an appealing alternative to less environmental friendly high temperature routes. In recent years, we have developed different fast, cost-effective, reproducible and easy wet chemistry routes for the synthesis of pure, doped and mixed metal oxide colloids. The prepared materials are interesting for different functional applications, ranging from catalysis to bioimaging, to optics and photonics. In particular, by using coprecipitation, sol-gel, miniemulsion, hydro- and solvothermal syntheses, we succeeded in preparing nanostructured pure and doped ZnO, different ferrites of bivalent metals and metal/metal oxide nanocomposites (M/M’Ox, M=Au, Pd, M’=Zn, Ti). Mixed oxide ferrites of bivalent metals were prepared through coprecipitation of the metal oxalates from a water solution of the metal salts. Analogous compounds could be also prepared by hydrothermal synthesis, yielding already at 100°C pure phases with smaller crystallite size compared to the former route [3]. The preparation of nanosized ZnO was firstly addressed by a classic colloidal route,4 whereas more recently, we have we also successfully explored the use of the w/o inverse miniemulsion route to prepare surfactant-functionalised nanocrystalline pure and doped ZnO colloids.[5] The adopted route exploits the micelles as nanoreactors for the precipitation of the desired oxide in a confined space. The same methodology was also for the obtainment of nanocrystalline Au and Pd nanoparticles on TiO2 or ZnO matrices.[6] Recently, this approach was successfully implemented to prepare also metal sulphide (CuS, ZnS) and halogenides (CaF2).

[1] W. Ostwald Die Welt der vernachlässigten Dimension, 1919 [2] H.D. Dörfler, Grenzflächen und kolloid-disperse Systeme-Physik und Chemie Springer Verlag, Berlin ; (b) D.H. Everett Basic principles of Colloid Science RSC London 1989 ; (c) R.J. Hunter, Foundation of colloid science, Clarendon Press Oxford 1989 [3] S. Diodati, S. Gross et al. Dalton Trans. 2012, 41, 5517-5525, S. Diodati, S. Gross et al. submitted to Green Chemistry [4] A. Famengo, S. Gross et al., Eur. J. Inorg. Chem. 2009, 33, 5017-5028 [5] P. Dolcet, M. Casarin, E. Tondello, S. Gross et al., J. Mater. Chem. 2012, 22, 1620-1626 ; P. Dolcet, F. Latini, M. Casarin, A. Speghini, E. Tondello, C. Foss, S, Diodati, L. Verin, A. Motta, S. Gross, European Journal of Inorganic Chemistry (2013) 2291 [6] P. Dolcet, N.A. Heutz, M. Casarin, K. Merz, S. Gross, Nanoscale, 2013