Controlled Attachment of Nanoparticles to Layered Oxides

<p>A series of oxide materials were modified with different nanoparticles (NPs). Novel cobalt@H₄Nb₆O₁₇ nanopeapod structures were fabricated and magnetic NPs modified oxide nanosheets and nanoscrolls were prepared. Both aqueous method and two-phase method were applied to prepare gold NPs onto oxide nanosheets, nanoscrolls and other nanocrystals.</p> <p>The combination of H₄Nb₆O₁₇ nanoscrolls and cobalt NPs generate a novel method to fabricate nanopeapod structures. Cobalt NPs were synthesized in the presence of exfoliated H₄Nb₆O₁₇ nanosheets and the resulting magnetic chain structures, formed due to the dipole-dipole interaction, were captured within scrolled lamella. The yield of peapod structures can be improved by using proper reagents and reaction temperatures. As similar method with iron oxide NPs also produced peapod-like structures in a low yield.</p> <p>Exfoliated Dion-Jacobson phase layered perovskite HLaNb₂O₇ (HLN), its organic derivate propoxyl-HLaNb₂O₇ (pHLN), Ruddlesden-Popper phase perovskite H₂SrTa₂O₇ (HSTO) and Aurivillius phase perovskite H₂W₂O₇ (HWO) were synthesized and functionalized with gold NPs by in-situ methods. Gold NPs were prepared by both an aqueous method and two-phase method. The size of NPs can be adjusted by different reaction times. Overall, the latter method shows a narrower size distribution and better dispersion. In addition, most gold NPs prepared by the two-phase method were attached on the surface of nanosheets and almost no free gold NPs were observed in solution. This approach should be applicable to most layered perovskites.</p> <p>The aqueous and two-phase methods were also applied on the preparation of gold NPs onto H₄Nb₆O₁₇ nanosheets and nanoscrolls. H₄Nb₆O₁₇ nanosheets were prepared by two approaches and showed similar gold NPs attachment. LiNbO₃ nanocrystals can be also modified with gold NPs by the two-phase method though free gold NPs were observed.</p> <p>Further studies involved the functionalization of layered perovskites and related compounds with magnetic NPs. Iron oxide and cobalt NPs were synthesized in the presence of layered perovskite and modified perovskite nanosheets were obtained.</p>

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation-Restricted

Discipline thesis:degree_discipline

Chemistry

Year

2012

Author dc:creator

• Yao, Yuan

Contributors dc:contributor

• Wiley, John B.
• Tarr, Matthew A.
• Stevens, Edwin D.

• Nanopeapod, Layered material, Niobate, Perovskite, Nanoparticle, Exfoliation
• Materials Chemistry

Repository record dc:identifier

https://scholarworks.uno.edu/td/1497

OAI identifier oai:identifier

oai:scholarworks.uno.edu:td-2434