Block copolymer mediated deposition of metal nanoparticles on germanium nanowires
Department of Chemistry, University of Alberta, Edmonton, Alberta, CanadaChemical Communications (Impact Factor: 6.72). 04/2007; DOI: 10.1039/b616883c
ABSTRACT Galvanic displacement, mediated by a diblock copolymer, leads to deposition of well dispersed gold and silver nanoparticles on germanium nanowires.
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ABSTRACT: Metal-oxide semiconductor nanowires (NWs) such as ZnO, β-Ga2O3 and SnO2 with diameters of tens of nanometres and lengths of many micrometres have been grown using micellar nanohybrids consisting of methacrylate-based diblock copolymers and noble metal nanoparticles (MNPs). Micellar Au and Pd MNPs with diameters as small as 2.3 ± 0.3 nm were deposited on Si(001) by spin coating or drop casting and metal-oxide NWs were grown by reactive vapor transport. A high yield of β-Ga2O3 NWs with diameters of approximately 40 nm, lengths > 10 μm and a monoclinic crystal structure were obtained at 900 °C with the largest MNPs. These exhibited a broad, symmetric photoluminescence (PL) spectrum centred at 2.3 eV attributed to defect states situated energetically in the energy band gap of β-Ga2O3. We find that a reduction in the size of the MNPs below 10 nm leads to the formation of necklace like β-Ga2O3 NWs via the encapsulation of the MNPs which act as catalytic centres for the formation of branched nanostructures along the length of the β-Ga2O3 NWs that are also responsible for a blue shift in the PL at 2.8 eV as a result of quantum confinement. This was not observed upon reducing the density of MNPs or in the case of ZnO or SnO2 NWs grown with the smallest of MNPs probably due to differences in surface energy. We show that polymethacrylate-noble MNPs may be patterned directly by electron beam lithography and may be exploited for the selective location growth of semiconductor NWs while we also discuss the difference between the sizes of the hybrid polymer-MNPs and MO NWs which is attributed to agglomeration.RSC Advances 05/2012; 2(10):4370-4376. DOI:10.1039/C2RA01072K · 3.71 Impact Factor
- Advanced Materials 12/2008; 20(24):4789-4792. DOI:10.1002/adma.200703233 · 15.41 Impact Factor
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ABSTRACT: Colloidal hybrid nanoparticles, which contain multiple inorganic domains that are joined together through solid–solid interfaces, exhibit particle multifunctionality as well as new and enhanced properties that can emerge from the particle–particle interactions. These hybrid nanoparticles are typically synthesized using heterogeneous seeded nucleation of one nanoparticle on the surface of another as well as using phase segregation, surface dewetting of core–shell nanoparticles, and the fusion of premade nanoparticles. However, to expand the materials diversity and the potential range of applications of such systems, alternative routes to heterogeneous seeded nucleation are needed. Here, we show that solution–liquid–solid and related supersaturation-precipitation strategies, traditionally used in the synthesis of 1D structures such as nanowires and nanorods, can also be applied to the synthesis of colloidal hybrid nanoparticles. Specifically, we show that colloidal Au and Ag nanoparticles can serve as seeds for the growth of colloidal Au–Ge and Ag–Ge heterodimers upon reaction with Ge(HMDS)2 (Ge(II)bis(hexamethyldisilylamide)) at 290 and 320 °C, respectively. By modifying the size of the seed nanoparticles and the amount of Ge(HMDS)2, the widths and lengths of the Ge domains can be systematically tuned. Additionally, the Ge domains can serve as site-selective templates for the galvanic deposition of metal nanoparticles, forming trimeric Au–Ge–(Ag)n nanostructures. This alternate route to colloidal hybrid nanoparticles facilitates the integration of previously inaccessible group IV elements, and it could open the door to the design and synthesis of a wide range of new functional colloidal nanostructures.Chemistry of Materials 10/2013; 25(21):4304–4311. DOI:10.1021/cm4024452 · 8.54 Impact Factor
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