INSP-CNRS Paris, FRANCE
Title: Reactive surface sites at metal oxide nanoparticles: from fundamental studies to potential medical application
Biography: Slavica Stankic
The ubiquity of oxides in dispersed form has prompted research strategies in two directions: understanding the existing materials by means of appropriate reference systems and tailoring the desired properties through innovative syntheses. In this talk I will show on examples of two prototype oxides, ZnO and MgO, to which extent they can be used as model systems for probing surface reactivity.
When studied in parallel with DFT calculations, surface hydroxylation, provided either by adsorbing H2O or H2, turned to be a win-win combination for a precise surface site identification. In that manner, we have demonstrated that ZnO nanopowders behave as multi-facet single crystals involving (10-10), (11-20), (0001) and (000-1) surfaces with the polar orientations corresponding to 25% of the total surface area . Moreover, we were able to report on water structures on ZnO(11-20) for the first time. Similarly, combining DFT and H2-Infrared spectroscopy on MgO nanocubes, we proposed a model in which multisite dissociation of hydrogen is suggested to occur on mono- and di-atomic steps at (001) MgO surface .
Nanoparticles of a well-defined size, shape, and surface termination are required for studying the reactions occurring over their surface. A strong emphasis in our work is, therefore, given to govern the synthesis pathways when producing desired nanoparticles, either in pure or doped form. Accordingly, an example of ruling the particles surface termination by controlling synthesis parameters will be presented in this talk .
Finally, I will also show how the interactions between water and nanoparticles surface can be used for studying particles dissolution as a function of their size . This is especially important in case of mixed form of ZnO and MgO (ZnMgO)  which, as I will be demonstrating in short, exhibits a promising potential for medical applications as an alternative to existing antibiotics [3,5,6].