@article{LiebigHenningSarhanetal.2018,
  author    = {Liebig, Ferenc and Henning, Ricky and Sarhan, Radwan Mohamed and Prietzel, Claudia Christina and Bargheer, Matias and Koetz, Joachim},
  title     = {A new route to gold nanoflowers},
  series = {Nanotechnology},
  volume    = {29},
  journal   = {Nanotechnology},
  number    = {18},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0957-4484},
  doi       = {10.1088/1361-6528/aaaffd},
  pages     = {8},
  year      = {2018},
  abstract  = {Catanionic vesicles spontaneously formed by mixing the anionic surfactant bis(2-ethylhexyl)sulfosuccinate sodium salt with the cationic surfactant cetyltrimethylammonium bromide were used as a reducing medium to produce gold clusters, which are embedded and well-ordered into the template phase. The gold clusters can be used as seeds in the growth process that follows by adding ascorbic acid as a mild reducing component. When the ascorbic acid was added very slowly in an ice bath round-edged gold nanoflowers were produced. When the same experiments were performed at room temperature in the presence of Ag+ ions, sharp-edged nanoflowers could be synthesized. The mechanism of nanoparticle formation can be understood to be a non-diffusion-limited Ostwald ripening process of preordered gold nanoparticles embedded in catanionic vesicle fragments. Surface-enhanced Raman scattering experiments show an excellent enhancement factor of 1.7 . 10(5) for the nanoflowers deposited on a silicon wafer.},
  language  = {en}
}
@article{ElNagarLauermannSarhanetal.2018,
  author    = {El-Nagar, Gumaa A. and Lauermann, Iver and Sarhan, Radwan Mohamed and Roth, Christina},
  title     = {Hierarchically structured iron-doped silver (Ag-Fe) lotus flowers for an efficient oxygen reduction reaction},
  series = {Nanoscale},
  volume    = {10},
  journal   = {Nanoscale},
  number    = {15},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {2040-3364},
  doi       = {10.1039/c8nr00020d},
  pages     = {7304 -- 7310},
  year      = {2018},
  abstract  = {The development of cheap and efficient electrocatalysts for the oxygen reduction reaction (ORR) is vital for the immediate commercialization of fuel cells which are still limited by the high cost and low performance of the utilized commercial Pt-based electrodes. As a promising alternative, this study reports on the synthesis of hierarchical iron-doped silver lotus flowers (AgFelotus) by a facile chemical procedure as robust and efficient ORR electrocatalysts. Succinic acid was used as a structure directing agent to tune the morphology of undoped and iron-doped silver particles. In the absence of succinic acid, ball-like silver particles were obtained, while using 2 mM succinic acid led to peony-like flower structures. The doping of silver peony-flowers with iron resulted in lotus-like flower structures with high electrocatalytic activity for ORR together with outstanding tolerance against poisoning with various hydrocarbon (HC) impurities, in situ generated during fuel cell operation, as well as different fuels from anodic crossover. AgFelotus exhibited a superior ORR activity with more than 40 times higher stability than the commercial Pt/C catalyst in alkaline media. This substantial performance enhancement is attributed to the unique lotus-like flower structures providing more electroactive surface sites, in addition to the iron dopants which facilitate ORR charge transfer.},
  language  = {en}
}
@misc{SarhanKoopmanSchuetzetal.2018,
  author    = {Sarhan, Radwan Mohamed and Koopman, Wouter-Willem Adriaan and Schuetz, Roman and Schmid, Thomas and Liebig, Ferenc and Koetz, Joachim and Bargheer, Matias},
  title     = {The importance of plasmonic heating for the plasmondriven photodimerization of 4-nitrothiophenol},
  series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  number    = {698},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-42719},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427197},
  pages     = {8},
  year      = {2018},
  abstract  = {Metal nanoparticles form potent nanoreactors, driven by the optical generation of energetic electrons and nanoscale heat. The relative influence of these two factors on nanoscale chemistry is strongly debated. This article discusses the temperature dependence of the dimerization of 4-nitrothiophenol (4-NTP) into 4,4′-dimercaptoazobenzene (DMAB) adsorbed on gold nanoflowers by Surface-Enhanced Raman Scattering (SERS). Raman thermometry shows a significant optical heating of the particles. The ratio of the Stokes and the anti-Stokes Raman signal moreover demonstrates that the molecular temperature during the reaction rises beyond the average crystal lattice temperature of the plasmonic particles. The product bands have an even higher temperature than reactant bands, which suggests that the reaction proceeds preferentially at thermal hot spots. In addition, kinetic measurements of the reaction during external heating of the reaction environment yield a considerable rise of the reaction rate with temperature. Despite this significant heating effects, a comparison of SERS spectra recorded after heating the sample by an external heater to spectra recorded after prolonged illumination shows that the reaction is strictly photo-driven. While in both cases the temperature increase is comparable, the dimerization occurs only in the presence of light. Intensity dependent measurements at fixed temperatures confirm this finding.},
  language  = {en}
}
@article{LiebigSarhanPrietzeletal.2018,
  author    = {Liebig, Ferenc and Sarhan, Radwan Mohamed and Prietzel, Claudia Christina and Schmitt, Clemens Nikolaus Zeno and Bargheer, Matias and Koetz, Joachim},
  title     = {Tuned Surface-Enhanced raman scattering performance of undulated Au@Ag triangles},
  series = {ACS applied nano materials},
  volume    = {1},
  journal   = {ACS applied nano materials},
  number    = {4},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {2574-0970},
  doi       = {10.1021/acsanm.8b00570},
  pages     = {1995 -- 2003},
  year      = {2018},
  abstract  = {Negatively charged ultraflat gold nanotriangles (AuNTs) stabilized by the anionic surfactant dioctyl sodium sulfosuccinate (AOT) were reloaded with the cationic surfactant benzylhexadecyldimethylammonium chloride (BDAC). Because of the spontaneous formation of a catanionic AOT micelle/BDAC bilayer onto the surface of the reloaded AuNTs, a reduction of Ag+ ions leads to the formation of spherical silver nanoparticles (AgNPs). With increasing concentration of AgNPs on the AuNTs, the localized surface plasmon resonance (LSPR) is shifted stepwise from 1300 to 800 nm. The tunable LSPR enables to shift the extinction maximum to the wavelength of the excitation laser of the Raman microscope at 785 nm. Surface-enhanced Raman scattering (SERS) experiments performed under resonance conditions show an SERS enhancement factor of the analyte molecule rhodamine RG6 of 5.1 X 10(5), which can be related to the silver hot spots at the periphery of the undulated gold nanoplatelets.},
  language  = {en}
}
@article{LiebigSarhanPrietzeletal.2018,
  author    = {Liebig, Ferenc and Sarhan, Radwan Mohamed and Prietzel, Claudia Christina and Th{\"u}nemann, Andreas F. and Bargheer, Matias and Koetz, Joachim},
  title     = {Undulated Gold Nanoplatelet Superstructures},
  series = {Langmuir},
  volume    = {34},
  journal   = {Langmuir},
  number    = {15},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/acs.langmuir.7b02898},
  pages     = {4584 -- 4594},
  year      = {2018},
  abstract  = {Negatively charged flat gold nanotriangles, formed in a vesicular template phase and separated by an AOT-micelle-based depletion flocculation, were reloaded by adding a cationic polyelectrolyte, that is, a hyperbranched polyethylenimine (PEI). Heating the system to 100 degrees C in the presence of a gold chloride solution, the reduction process leads to the formation of gold nanoparticles inside the polymer shell surrounding the nanoplatelets. The gold nanoparticle formation is investigated by UV-vis spectroscopy, small-angle X-ray scattering, and dynamic light scattering measurements in combination with transmission electron microscopy. Spontaneously formed gold clusters in the hyperbranched PEI shell with an absorption maximum at 350 nm grow on the surface of the nanotriangles as hemispherical particles with diameters of similar to 6 nm. High-resolution micrographs show that the hemispherical gold particles are crystallized onto the {111} facets on the bottom and top of the platelet as well as on the edges without a grain boundary. Undulated gold nanoplatelet superstructures with special properties become available, which show a significantly modified performance in SERS-detected photocatalysis regarding both reactivity and enhancement factor.},
  language  = {en}
}