TY - JOUR A1 - El-Nagar, Gumaa A. A1 - Lauermann, Iver A1 - Sarhan, Radwan Mohamed A1 - Roth, Christina T1 - Hierarchically structured iron-doped silver (Ag-Fe) lotus flowers for an efficient oxygen reduction reaction JF - Nanoscale N2 - 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. Y1 - 2018 U6 - https://doi.org/10.1039/c8nr00020d SN - 2040-3364 SN - 2040-3372 VL - 10 IS - 15 SP - 7304 EP - 7310 PB - Royal Society of Chemistry CY - Cambridge ER - TY - GEN A1 - El-Nagar, Gumaa A. A1 - Lauermann, Iver A1 - Sarhan, Radwan Mohamed A1 - Roth, Christina T1 - Hierarchically structured iron-doped silver (Ag-Fe) lotus flowers for an efficient oxygen reduction reaction (vol 10, pg 7304 -7310, 2018) T2 - Nanoscale Y1 - 2019 U6 - https://doi.org/10.1039/c9nr90131k SN - 2040-3364 SN - 2040-3372 VL - 11 IS - 24 SP - 11975 EP - 11975 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - El-Nagar, Gumaa A. A1 - Sarhan, Radwan Mohamed A1 - Abouserie, Ahed A1 - Maticiuc, Natalia A1 - Bargheer, Matias A1 - Lauermann, Iver A1 - Roth, Christina T1 - Efficient 3D-Silver Flower-like Microstructures for Non-Enzymatic Hydrogen Peroxide (H2O2) Amperometric Detection JF - Scientific reports Y1 - 2017 U6 - https://doi.org/10.1038/s41598-017-11965-9 SN - 2045-2322 VL - 7 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Mei, Shilin A1 - Jafta, Charl J. A1 - Lauermann, Iver A1 - Ran, Qidi A1 - Kaergell, Martin A1 - Ballauff, Matthias A1 - Lu, Yan T1 - Porous Ti4O7 Particles with Interconnected-Pore Structure as a High-Efficiency Polysulfide Mediator for Lithium-Sulfur Batteries JF - Advanced functional materials N2 - Multifunctional Ti4O7 particles with interconnected-pore structure are designed and synthesized using porous poly(styrene-b-2-vinylpyridine) particles as a template. The particles can work efficiently as a sulfur-host material for lithium-sulfur batteries. Specifically, the well-defined porous Ti4O7 particles exhibit interconnected pores in the interior and have a high-surface area of 592 m(2) g(-1); this shows the advantage of mesopores for encapsulating of sulfur and provides a polar surface for chemical binding with polysulfides to suppress their dissolution. Moreover, in order to improve the conductivity of the electrode, a thin layer of carbon is coated on the Ti4O7 surface without destroying its porous structure. The porous Ti4O7 and carbon-coated Ti4O7 particles show significantly improved electrochemical performances as cathode materials for Li-S batteries as compared with those of TiO2 particles. KW - lithium-sulfur batteries KW - porous particles KW - poly(styrene-b-2-vinylpyridine) (PS-P2VP) KW - Ti4O7 Y1 - 2017 U6 - https://doi.org/10.1002/adfm.201701176 SN - 1616-301X SN - 1616-3028 VL - 27 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Steigert, Alexander A1 - Kojda, Sandrino Danny A1 - Ibaceta-Jaña, Josefa Fernanda A1 - Abou-Ras, Daniel A1 - Gunder, René A1 - Alktash, Nivin A1 - Habicht, Klaus A1 - Wagner, Markus Raphael A1 - Klenk, Reiner A1 - Raoux, Simone A1 - Szyszka, Bernd A1 - Lauermann, Iver A1 - Muydinov, Ruslan T1 - Water-assisted crystallization of amorphous indium zinc oxide films JF - Materials today. Communications N2 - Transparent conductive materials based on indium oxide remain yet irreplaceable in various optoelectronic applications. Amorphous oxides appear especially attractive for technology as they are isotropic, demonstrate relatively high electron mobility and can be processed at low temperatures. Among them is indium zinc oxide (IZO) with a large zinc content that is crucial for keeping the amorphous state but redundant for the doping. In this work we investigated water-free and water containing IZO films obtained by radio frequency sputtering. The correlation between temperature driven changes of the chemical state, the optical and electrical properties as well as the progression of crystallization was in focus. Such characterization methods as: scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, temperature dependent Hall-effect measurements and others were applied. Temperature dependent electrical properties of amorphous IZO and IZO:H2O films were found to evolve similarly. Based on our experience in In2O3:H2O (In2O3:H or IOH) we proposed an explanation for the changes observed. Water admixture was found to decrease crystallization temperature of IZO significantly from similar to 550 degrees C to similar to 280 degrees C. Herewith, the presence and concentration of water and/or hydroxyls was found to determine Zn distribution in the film. In particular, Zn enrichment was detected at the film's surface respective to the high water and/or hydroxyl amount. Raman spectra revealed a two-dimensional crystallization of w-ZnO which precedes regardless water presence an extensive In2O3 crystallization. An abrupt loss of electron mobility as a result of crystallization was attributed to the formation of ZnO interlayer on grain boundaries. KW - IZO KW - Thin films KW - TCOs KW - Crystallization KW - Water-assisted crystallization Y1 - 2022 U6 - https://doi.org/10.1016/j.mtcomm.2022.103213 SN - 2352-4928 VL - 31 PB - Elsevier CY - Amsterdam ER -