TY - JOUR A1 - de O. Primo, J. A1 - Horsth, D.F. A1 - de S. Correa, J. A1 - Das, A. A1 - Bittencourt, C. A1 - Umek, P. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Yusenko, Kirill A1 - Zanetta, C. A1 - Anaissi, F.J. T1 - Synthesis and Characterization of Ag/ZnO Nanoparticles for Bacteria Disinfection in Water N2 - n this study, two green synthesis routes were used for the synthesis of Ag/ZnO nanoparticles, using cassava starch as a simple and low-cost effective fuel and Aloe vera as a reducing and stabilizing agent. The Ag/ZnO nanoparticles were characterized and used for bacterial dis- infection of lake water contaminated with Escherichia coli (E. coli). Characterization indicated the formation of a face-centered cubic structure of metallic silver nanoparticles with no insertion of Ag into the ZnO hexagonal wurtzite structure. Physicochemical and bacteriological analyses described in “Standard Methods for the Examination of Water and Wastewater” were used to evaluate the efficiency of the treatment. In comparison to pure ZnO, the synthesized Ag/ZnO nanoparticles showed high efficiencies against Escherichia coli (E. coli) and general coliforms present in the lake water. These pathogens were absent after treatment using Ag/ZnO nanoparticles. The results indicate that Ag/ZnO nanoparticles synthesized via green chemistry are a promising candidate for the treatment of wastewaters contaminated by bacteria, due to their facile preparation, low-cost synthesis,and disinfection efficiency. KW - Synchrotron KW - BAMline PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-562440 DO - https://doi.org/10.3390/nano12101764 SN - 2079-4991 VL - 12 IS - 10 SP - 1 EP - 18 PB - MDPI CY - Basel AN - OPUS4-56244 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Oliveira Guilherme Buzanich, Ana A1 - Cakir, Cafer Tufan A1 - Radtke, Martin A1 - Haider, M. Bilal A1 - Emmerling, Franziska A1 - F. M. Oliveira, P. A1 - Michalchuk, Adam T1 - Dispersive x-ray absorption spectroscopy for time-resolved in situ monitoring of mechanochemical reactions N2 - X-ray absorption spectroscopy (XAS) provides a unique, atom-specific tool to probe the electronic structure of solids. By surmounting long-held limitations of powder-based XAS using a dynamically averaged powder in a Resonant Acoustic Mixer (RAM), we demonstrate how time-resolved in situ (TRIS) XAS provides unprecedented detail of mechanochemical synthesis. The use of a custom-designed dispersive XAS (DXAS) setup allows us to increase the time resolution over existing fluorescence measurements from ∼15 min to 2 s for a complete absorption spectrum. Hence, we here establish TRIS-XAS as a viable method for studying mechanochemical reactions and sampling reaction kinetics. The generality of our approach is demonstrated through RAM-induced (i) bottom-up Au nanoparticle mechanosynthesis and (ii) the synthesis of a prototypical metal organic framework, ZIF-8. Moreover, we demonstrate that our approach also works with the addition of a stainless steel milling ball, opening the door to using TRIS-DXAS for following conventional ball milling reactions. We expect that our TRIS-DXAS approach will become an essential part of the mechanochemical tool box. KW - In situ studies KW - Dipsersive XAS KW - Mechanochemistry KW - Time-resolved PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-567659 DO - https://doi.org/10.1063/5.0130673 SN - 1089-7690 VL - 157 IS - 21 SP - 1 EP - 12 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-56765 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Radtke, Martin A1 - Buzanich, Günter A1 - de Oliveira Guilherme Buzanich, Ana A1 - Reinholz, Uwe A1 - Riesemeier, Heinrich A1 - Scharf, O. A1 - Scholz, Philipp A1 - Guerra, M.F. T1 - Double Dispersive X-Ray Fluorescence (D2XRF) based on an Energy Dispersive pnCCD detector for the detection of platinum in gold N2 - With the aim of improving limits of detection (LOD) of trace elements in a matrix with adjacent fluorescence energies, a simple double dispersive X-ray fluorescence detection system (D2XRF) was constructed to operate at the beamlines BAMline and the mySpot @ BESSY II. This system is based on the combination of a crystal analyzer with an energy resolving single photon counting pnCCD. Without further collimators, the efficient suppression of the background by the pnCCD and the good energy resolution of the crystal results in improved LOD. In first order reflections, an energy resolution of 13 eV for Cu Kα was reached, and an energy range of 1 keV was covered in one shot. This new system was applied to the detection of platinum (Pt) in gold leaves with a LOD of 0.9 mg/kg, which is the lowest attained by totally non-destructive methods nowadays. The presence of Pt in gilded objects from Abydos and Byzantine mosaics provides vital information, as it indicates the alluvial origin of the gold for these examples. KW - Platinum Wavelength dispersive D2XRF KW - Gold Synchrotron XRF PY - 2016 DO - https://doi.org/10.1016/j.microc.2015.10.039 VL - 125 SP - 56 EP - 61 PB - Elsevier Science CY - Amsterdam AN - OPUS4-35777 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Edzards, Joshua A1 - Saßnick, Holger-Dietrich A1 - de Oliveira Guilherme Buzanich, Ana A1 - Valencia, Ana M. A1 - Emmerling, Franziska A1 - Beyer, Sebastian A1 - Cocchi, Caterina T1 - Effects of Ligand Substituents on the Character of Zn-Coordination in Zeolitic Imidazolate Frameworks N2 - Due to their favorable properties and high porosity, zeolitic imidazolate frameworks (ZIFs) have recently received much limelight for key technologies such as energy storage, optoelectronics, sensorics, and catalysis. Despite widespread interest in these materials, fundamental questions regarding the zinc coordination environment remain poorly understood. By focusing on zinc(II)2-methylimidazolate (ZIF-8) and its tetrahedrally coordinated analogues with Br-, Cl-, and H-substitution in the 2-ring position, we aim to clarify how variations in the local environment of Zn impact the charge distribution and the electronic properties of these materials. Our results from densityfunctional theory confirm the presence of a Zn coordinative bond with a large polarization that is quantitatively affected by different substituents on the organic ligand. Moreover, our findings suggest that the variations in the Zn coordination induced by the functionalization have a negligible effect on the electronic structure of the considered compounds. On the other hand, halogen terminations of the ligands lead to distinct electronic contributions in the vicinity of the frontier region which ultimately reduce the band gap size by a few hundred millielectron volts. Experimental results obtained from X-ray absorption spectroscopy (Zn K-edge) confirm the trends predicted by theory and, together with them, contribute to a better understanding of the structure−property relationships that are needed to tailor ZIFs for target applications. KW - Surfaces KW - Physical and Theoretical Chemistry KW - General Energy KW - Electronic KW - Coatings and Films KW - Optical and Magnetic Materials PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-589117 DO - https://doi.org/10.1021/acs.jpcc.3c06054 SN - 1932-7447 VL - 127 IS - 43 SP - 21456 EP - 21464 PB - American Chemical Society (ACS) AN - OPUS4-58911 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Flatken, M. A. A1 - Radicchi, E. A1 - Wendt, R. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Härk, E. A1 - Pascual, J. A1 - Mathies, F. A1 - Shargaieva, O. A1 - Prause, A. A1 - Dallmann, A. A1 - De Angelis, F. A1 - Hoell, A. A1 - Abate, A. T1 - Role of the Alkali Metal Cation in the Early Stages of Crystallization of Halide Perovskites N2 - ABX3 metal halide perovskites revolutionized the research and development of new optoelectronics, including solar cells and light-emitting diodes. Processing polycrystalline thin films from precursor solutions is one of the core advantages of these materials since it enables versatile and cost-effective manufacturing. The perovskite film morphology, that is, continuous substrate coverage and low surface roughness, is of paramount importance for highly efficient solar cells and optoelectronic devices in general. Controlling the chemistry of precursor solutions is one of the most effective strategies to manage the perovskite film morphology. Herein, we show the fundamental influence of the A-site cation composition on the perovskite precursor arrangement and the consequent film formation. Extended X-ray absorption fine structure spectroscopy and small-angle X-ray scattering give unprecedented insights into the complex structural chemistry of the perovskite precursors and, in particular, their repulsive interactions as a crucial parameter for colloidal stability. Combining these techniques with in situ grazing incidence wide-angle X-ray scattering during thin-film formation allows us to identify the mechanism for using alkali metals as a decisive criterion to control the colloidal stability of the perovskite precursor and thus the thin-film morphology. We illustrate the fundamental principle behind the systematic use of alkali metals regardless of whether they are incorporated in the lattice or not. Hence, this work provides tools to selectively control the morphology and crystal growth in present and future systems KW - MAPbI3 perovskites KW - Halide Perovskites KW - X-ray absorption spectroscopy PY - 2022 DO - https://doi.org/10.1021/acs.chemmater.1c03563 SN - 0897-4756 VL - 34 IS - 3 SP - 1121 EP - 1131 PB - American Chemical Society AN - OPUS4-54713 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Olivera, Paulo A1 - Michalchuk, Adam A1 - de Oliveira Guilherme Buzanich, Ana A1 - Bienert, Ralf A1 - Torresi, R. A1 - Camargo, P. A1 - Emmerling, Franziska T1 - Tandem X-ray absorption spectroscopy and scattering for in situ time-resolved monitoring of gold nanoparticle mechanosynthesis N2 - Current time-resolved in situ approaches limit the scope of mechanochemical investigations possible. Here we develop a new, general approach to simultaneously follow the evolution of bulk atomic and electronic structure during a mechanochemical synthesis. This is achieved by coupling two complementary synchrotron-based X-ray methods: X-ray absorption spectroscopy (XAS) and X-ray diffraction. We apply this method to investigate the bottom-up mechanosynthesis of technologically important Au micro and nanoparticles in the presence of three different reducing agents, hydroquinone, sodium citrate, and NaBH4. Moreover, we show how XAS offers new insight into the early stage generation of growth species (e.g. monomers and clusters), which lead to the subsequent formation of nanoparticles. These processes are beyond the detection capabilities of diffraction methods. This combined X-ray approach paves the way to new directions in mechanochemical research of advanced electronic materials. KW - Mechanochemistry KW - XANES KW - X-ray diffraction KW - Nano particles PY - 2020 DO - https://doi.org/10.1039/d0cc03862h SN - 1364-548X VL - 56 SP - 10329 EP - 10332 PB - Royal Society of Chemistry AN - OPUS4-51760 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Durlo Tambara, Luís Urbano A1 - Nikoonasab, Ali A1 - Radtke, Martin A1 - de Oliveira Guilherme Buzanich, Ana A1 - Gluth, Gregor T1 - Determination of the oxidation depths of ground granulated blast furnace slag-containing cement pastes using Mn K-edge X-ray absorption near-edge structure spectroscopy N2 - The redox potential of the pore solution of hardened cements containing ground granulated blast furnace slag (GGBFS) affects reinforcement corrosion and immobilization of radioactive waste. Here, Mn K-edge X-ray absorption near-edge structure (XANES) spectroscopy was applied to determine the depth profile of the oxidation state of manganese in hardened GGBFS-containing cement pastes. Manganese was oxidized in the outer regions of some of the pastes, but the depth to which this occurred was not identical with the ‘blue-green/white color change front’, usually interpreted as indicating oxidation of sulfur species. For CEM III/B, the color change of the material was gradual and thus unsuitable for a precise determination of the oxidation depth, while for the alkali-activated slag, a distinct color change front was found, but full oxidation of manganese and sulfur had not occurred in the brighter region. Mn K-edge XANES spectroscopy is thus a more reliable method than the determination of the visual color change front to follow the ingress of the oxidation front. KW - Manganese KW - Oxidation KW - Sulfide KW - Alkali-activated materials KW - Redox conditions PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-651469 DO - https://doi.org/10.1111/jace.70445 SN - 0002-7820 SN - 1551-2916 VL - 109 IS - 1 SP - 1 EP - 11 PB - Wiley CY - Oxford AN - OPUS4-65146 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thiodjio Sendja, Bridinette A1 - Tchouank Tekou, Carol Trudel A1 - Prinz, Carsten A1 - de Oliveira Guilherme Buzanich, Ana T1 - Adsorptive performance of single-walled carbon nanotubes for divalent manganese sorption characterized by X-ray absorption spectroscopy N2 - The adsorptive performance of divalent manganese onto single-walled carbon nanotubes (SWCNTs) is investigated by X-ray absorption spectroscopy (XAS). The study is focused on the one hand, on the use of SWCNT as adsorbent to remove divalent manganese II) pollutant controlling batch parameters such as pH, adsorbent dose and contact time; and on the other hand, on the characterization of manganese adsorbed by SWCNT (Mn-SWCNT) adsorbent to probe the chemical composition, oxidation state, and local structural environment of Mn absorber. Freundlich adsorption isotherm well fitted the experimental data and suggested the maximum adsorption capacity at pH 2. Ion exchange was proposed as the main adsorption mechanism for removing manganese using SWCNT. XAS results revealed the change in the oxidation state of manganese. The effect of pH, adsorbent dose, and contact time is shown. XAS also showed that Mn-SWCNT material is principally composed of MnCl2, Mn2O3, MnO2, Mn3O4, and MnO in decreasing order with MnCl2 and Mn2O3 as major compounds. KW - Local environment KW - Single-walled carbon nanotubes KW - Divalent manganese KW - Adsorptive performance KW - X-ray absorption spectroscopy KW - Oxidation state PY - 2025 DO - https://doi.org/10.1007/s11696-025-04418-5 SN - 0366-6352 SP - 1 EP - 15 PB - Springer Science and Business Media LLC AN - OPUS4-64492 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gong, Mengjun A1 - Mehmood, Asad A1 - de Oliveira Guilherme Buzanich, Ana A1 - Fellinger, Tim-Patrick A1 - Jackson, Colleen A1 - Cui, Junyi A1 - Drazic, Goran A1 - Kucernak, Anthony T1 - Designing Co–N/C Cathode Catalysts with Dense Atomic Cobalt Sites for Enhanced PEMFC Performance N2 - Metal-nitrogen/carbon (M-N/C) catalysts, particularly those incorporating Fe,Co, or Mn, are among the most promising non-platinum group catalysts forthe acidic oxygen reduction reaction (ORR) in fuel cells. This study reports aCo-N/C catalyst featuring high (3 wt%) cobalt content exclusively present asatomic sites. Extended X-ray absorption fine structure analysis confirms atetrapyridinic Co-N4 coordination environment in the optimized (3.0)Co-N/C𝚫catalyst. The high cobalt loading leads to a significant density ofelectrochemically accessible active sites, 3.58 × 10 19 sites g−1 , quantified viathe nitrite stripping method. The catalyst demonstrates excellent ORR activityin a rotating ring-disk electrode setup, achieving a half-wave potential (E 1/2 ) of0.76 V at a low loading of 0.2 mg cm−2 and a mass activity of 3.5 A g−1 at 0.80VRHE . Single-cell hydrogen-oxygen PEMFC tests achieve a peak power densityexceeding 1.3 W cm−2 (iR-corrected). Under hydrogen-air condition, thecatalyst delivers 0.54 A cm−2 at 0.60 V (0.39 W cm−2 ). Despite the intrinsicallyhigher turnover frequency of Fe-based sites, the optimized(3.0)Co-N/C𝚫 catalyst achieves similar fuel cell performance to that of Fe-N/C,highlighting the critical role of site density in overall activity. KW - Fuel cells KW - Single atom catalysts KW - Oxygen reduction reaction KW - Non-precious catalysts PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-644276 DO - https://doi.org/10.1002/advs.202516060 SN - 2198-3844 SP - 1 EP - 11 PB - Wiley VHC-Verlag AN - OPUS4-64427 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Habibimarkani, Heydar A1 - Abram, Sarah-Luise A1 - de Oliveira Guilherme Buzanich, Ana A1 - Prinz, Carsten A1 - Sahre, Mario A1 - Hodoroaba, Vasile-Dan A1 - Radnik, Jörg T1 - In-depth analysis of FeNi-based nanoparticles for the oxygen evolution reaction N2 - This study investigates the effect of varying iron-to-nickel ratios on the catalytic performance of Fe-Ni oxide nanoparticles (NPs) for the oxygen evolution reaction (OER). Addressing the issue of high energy wastage due to large overpotentials in OER, we synthesized and characterized different NP catalysts with different Fe: Ni oxide ratios. Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS), and X-ray Diffraction (XRD) were employed to determine the morphology, elemental and phase composition of the NPs. Furthermore, in-depth profiling with X-ray Photoelectron Spectroscopy (XPS) and Hard X-ray Photoelectron Spectroscopy (HAXPES) revealed that iron predominantly exists as oxide, while nickel exhibits both metallic and oxidic forms depending on the Fe content. XPS indicated an enrichment of iron at the NP surface, whereas HAXPES and EDS data agreed on the bulk stoichiometry. The assessment of the catalytic activity via cyclic voltammetry (CV) showed that the Fe: Ni ratio of 2:3 exhibited superior performance, characterized by lower overpotential and a smaller Tafel slope. KW - Fe-Ni oxide KW - Nanoparticles KW - OER KW - Catalytic performance KW - Cyclic voltammetry PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626932 UR - https://www.nature.com/articles/s41598-025-92720-3 DO - https://doi.org/10.1038/s41598-025-92720-3 VL - 15 IS - 1 SP - 1 EP - 17 PB - Springer Nature AN - OPUS4-62693 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Menga, D. A1 - Low, Jian Liang A1 - de Oliveira Guilherme Buzanich, Ana A1 - Paulus, B. A1 - Fellinger, Tim-Patrick T1 - The Tetrapyrollic Motif in Nitrogen Doped Carbons and M-N-C Electrocatalysts as Active Site in the Outer-Sphere Mechanism of the Alkaline Oxygen Reduction Reaction N2 - Development and fundamental understanding of precious-group-metal-free electrocatalysts is hampered by limitations in the quantification of the intrinsic activity of different catalytic sites and understanding the different reaction mechanisms. Comparing isomorphic nitrogen-doped carbons, Zn-N-Cs and Fe-N-Cs with the common tetrapyrrolic motif, a catalyst-independent outer-sphere rate-determining step in the alkaline oxygen reduction reaction is observed. Density functional theory (DFT) simulations on tetrapyrrolic model structures indicate the highest occupied molecular orbital (HOMO) level as a good descriptor for the catalytic activity. Contour plots suggest that the electron transfer occurs directly from the tetrapyrrolic coordination site, rather than from the metal center. Metal-free tetrapyrrolic N4 sites are discovered to be highly active oxygen reduction reaction (ORR) active sites in alkaline that reach turnover frequencies (TOF) of 0.33 and 1.84 s−1 at 0.80 and 0.75 VRHE in the order of magnitude of tetrapyrrolic Fe–N4 sites in the acidic ORR. While Zn-coordination lowers the HOMO level and therefore the catalytic activity, Fe-coordination lifts the HOMO level resulting in TOF values of 0.4 and 4 s−1 for tetrapyrrolic Fe–N4 sites at 0.90 and 0.85 VRHE, respectively. At higher mass activities, the peroxide reduction becomes rate-limiting, where highest peroxide production rates are observed for the nitrogen-doped carbon. KW - Tetrapyrollic KW - Motif KW - Nitrogen KW - Carbons KW - Alkaline Oxygen PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-606239 DO - https://doi.org/https://doi.org/10.1002/aenm.202400482 SN - 1614-6832 VL - 2024 SP - 1 EP - 8 PB - Wiley-VCH AN - OPUS4-60623 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -