Interfacial interactions drive structural transformations in sulfide nanoparticles

COLL 459

Carmen M. Goodell1, Benjamin Gilbert, BGilbert@lbl.gov2, Hengzhong Zhang, heng@eps.berkeley.edu3, Bin Chen, binchen@eps.berkeley.edu3, and Jillian Banfield4. (1) Earth and Planetary Science, UC Berkeley, UC Berkeley, Berkeley, CA 94720, (2) Earth Science Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road MS 90R1116, Berkeley, CA 94720, (3) Department of Earth and Planetary Science, University of California Berkeley, 307 McCone Hall, Berkeley, CA 94720, (4) Department of Earth & Planetary Science, University of California at Berkeley, 307 McCone Hall #4767, Berkeley, CA 94720
Inter-particle interactions and surface adsorption of ions can induce ordering in nanoparticles. For example, aggregation/disaggregation of 3 nm ZnS nanoparticles drives a reversible structural transformation (Huang et al. 2004). In addition, experiments and simulations show that adsorption of water to ZnS nanoparticle surfaces leads to an irreversible increase in structural order (Zhang et al. 2003). However, water adsorption also induces aggregation. In order to separate the effects of adsorption and aggregation and to determine the activation energy for the adsorption-driven reaction, we fixed the aggregation state by vacuum-drying nanoparticles before exposure to water vapor at different temperatures. Results confirmed that the adsorption of water molecules is a stronger determinant of the nanoparticle structure than the aggregation state. In order to further evaluate structure-directing surface interactions, nanoparticles were exposed to a variety of inorganic and organic ligands. Higher degrees of crystallinity are associated with electrostatic rather than van der Waals interactions.
 

Environmental Interfaces
8:30 AM-12:40 PM, Wednesday, 13 September 2006 Sir Francis Drake -- Empire Room, Oral

Division of Colloid & Surface Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006