Paper No. 5
Presentation Time: 9:05 AM
RESPONSES OF NANOPARTICLES TO DIFFERENT TYPES OF SURFACE ENVIRONMENTS AND LIGANDS
ZHANG, Hengzhong
1,
WAYCHUNAS, Glenn A.2, CHEN, Bin
1, REN, Yang
3 and BANFIELD, Jill F.
1, (1)Earth and Planetary Sciences, University of California, Berkeley, CA 94720, (2)Earth Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, (3)Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, gawaychunas@lbl.gov
Nanoparticles prepared for technological purposes are generally stabilized by surface ligands that passivate them against further growth, and unwanted chemical reactions. Such stabilization (or lack of it) can also have a major effect on the nanoparticle structure by affecting the strain profile throughout the particle, and controlling whether structural transformations are readily promoted. Natural nanoparticles may also be stabilized by the presence of a surface layer or thin shell of sorbed ligands, and this study investigated how different ligand types (NaCl, CaCl
2, Na
2SO
4, C
6H
6S, H
2O, C
6H
5Cl, CH
3OH) affected the internal structures and strain in synthetic 3 nm ZnS nanoparticles. The work was in part motivated by several earlier studies of ZnS strain and aggregation-based transformations by Ben Gilbert and colleagues, that indicated the major influence of nanoparticle surface environment [1-3].
Using analysis of the pair-distribution-function (PDF) obtained from high energy x-ray scattering at the Advanced Photon Source, it was found that the stronger the surface ligand or surface complex binding interaction, the larger was the well-defined crystalline core of the nanoparticles, and the thinner the surface shell having high disorder [4]. Analogous molecular dynamics simulations of the ligand-nanoparticle interactions yielded very similar results. Ab initio calculations using a segment of the nanoparticle surface and the sorbed molecular group were used to quantify the interaction strength. The study verified that PDF analysis can ascertain the effect of surface ligand binding on nanoparticle structure, thereby indicating the magnitude of the surface interactions.
1. B. Gilbert, F. Huang, H. Zhang, G. A. Waychunas, and J. F. Banfield, Science 305, 651 (2004).
2. B, Gilbert, F. Huang, Z. Lin, C. Goodell, H. Zhang, and J. F. Banfield, Nano Lett. 6, 605 (2006).
3. F. Huang, B. Gilbert, H. Zhang, and J. F. Banfield, Phys. Rev. Lett. 92, 155501 (2004).
4. H. Zhang, B. Chen, Y. Ren, G. A. Waychunas, and J. F. Banfield, Phys. Rev. B 81, 125444 (2010).
