Date of Award
Wiley, John B.
Tarr, Matthew A.
Stevens, Edwin D.
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.
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.
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.
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.
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.
Yao, Yuan, "Controlled Attachment of Nanoparticles to Layered Oxides" (2012). University of New Orleans Theses and Dissertations. 1497.