TY - JOUR
A1 - Heinekamp, Christian
A1 - Kneiske, Sönke
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Ahrens, Mike
A1 - Braun, Thomas
A1 - Emmerling, Franziska
T1 - A fluorolytic sol-gel route to access an amorphous Zr fluoride catalyst: A useful tool for C-F bond activation
N2 - A route to a ZrF4 catalyst active in room temperature Friedel–Crafts and dehydrofluorination reactions was developed via a fluorolytic sol–gel route, which was followed by a postfluorination step using a stream of CHClF2. The behaviour of different Zr(IV) precursors in a sol–gel reaction with anhydrous isopropanol/HF solution was investigated. The subsequent post-fluorination step was optimised in its temperature ramp and confirmed the necessity of a fluorination of the generated xerogels to obtain catalytic activity. The process is discussed in the context of the analysis of the materials using Brunauer–Emmett–Teller analysis (BET), powder X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The local structure of the amorphous catalyst was elucidated by extended X-ray absorption fine structure spectroscopy (EXAFS).
KW - Catalysis
KW - Heterogeneous catalysis
KW - C-F bond activation
KW - Postfluorination
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593433
DO - https://doi.org/10.1039/D3CY01439H
SN - 2044-4761
SP - 1
EP - 8
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-59343
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - C. Pardo Pérez, L.
A1 - Arndt, A.
A1 - Stojkovikj, S.
A1 - Y. Ahmet, I.
A1 - T. Arens,, J.
A1 - Dattila, F.
A1 - Wendt, R.
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Radtke, Martin
A1 - Davies, V.
A1 - Höflich, K.
A1 - Köhnen, E.
A1 - Tockhorn, P.
A1 - Golnak, R.
A1 - Xiao, J.
A1 - Schuck, G.
A1 - Wollgarten, M.
A1 - López, N.
A1 - T. Mayer, M.
T1 - Determining Structure-Activity Relationships in Oxide Derived CuSn Catalysts During CO2 Electroreduction Using X-Ray Spectroscopy
N2 - The development of earth-abundant catalysts for selective electrochemical CO2 conversion is a central challenge. Cu-Sn bimetallic catalysts can yield selective CO2 reduction toward either CO or formate. This study presents oxide-derived Cu-Sn catalysts tunable for either product and seeks to understand the synergetic effects between Cu and Sn causing these selectivity trends. The materials undergo significant transformations under CO2 reduction conditions, and their dynamic bulk and surface structures are revealed by correlating observations from multiple methods—X-ray absorption spectroscopy for in situ study, and quasi in situ X-ray photoelectron spectroscopy for surface sensitivity. For both types of catalysts, Cu transforms to metallic Cu0 under reaction conditions. However, the Sn speciation and content differ significantly between the catalyst types: the CO-selective catalysts exhibit a surface Sn content of 13 at. % predominantly present as oxidized Sn, while the formate-selective catalysts display an Sn content of ≈70 at. % consisting of both metallic Sn0 and Sn oxide species. Density functional theory simulations suggest that Snδ+ sites weaken CO adsorption, thereby enhancing CO selectivity, while Sn0 sites hinder H adsorption and promote formate production. This study reveals the complex dependence of catalyst structure, composition, and speciation with electrochemical bias in bimetallic Cu catalysts.
KW - Electrochemical CO2 conversion
KW - Cu catalysts
KW - X-ray absorption spectroscopy
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-547116
DO - https://doi.org/10.1002/aenm.202103328
SN - 1614-6832
VL - 12
IS - 5
SP - 2103328
PB - Wiley-VCH GmbH
AN - OPUS4-54711
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kunkel, B.
A1 - Kabelitz, Anke
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Wohlrab, S.
T1 - Increasing the Efficiency of Optimized V-SBA-15 Catalysts in the Selective Oxidation of Methane to Formaldehyde by Artificial Neural Network Modelling
N2 - The present study investigates the possibility of improving the selective oxidation of methane to formaldehyde over V-SBA-15 catalysts in two different ways. In a classical approach of catalyst optimization, the in situ synthesis of V-SBA-15 catalysts was optimized with regard to the applied pH value. Among the set of catalysts synthesized, a higher amount of incorporated vanadium, a higher content of polymeric VOx species as well as a less ordered structure of the support material were observed by increasing the pH values from 2.0 to 3.0. An optimum in performance during the selective oxidation of methane to formaldehyde with respect to activity and selectivity was found over V-SBA-15 prepared at a pH value of 2.5. With this knowledge, we have now evaluated the possibilities of reaction control using this catalyst. Specifically, artificial neural network modelling was applied after the collection of 232 training samples for obtaining insight into the influence of different reaction parameters (temperature; gas hourly space velocity (GHSV); and concentration of O2, N2 and H2O) onto methane conversion and selectivity towards formaldehyde.
This optimization of reaction conditions resulted in an outstanding high space-time yield of 13.6 kgCH2O∙kgcat∙h−1
KW - Artificial neural network modelling
KW - Selective oxidation
KW - Molecular VOx catalysts
KW - Formaldehyde
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517420
DO - https://doi.org/10.3390/catal10121411
VL - 10
IS - 12
SP - 1411
PB - MDPI
AN - OPUS4-51742
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Brieger, C.
A1 - Melke, J.
A1 - van der Bosch, N.
A1 - Reinholz, Uwe
A1 - Riesemeier, Heinrich
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Krishna Kayarkatte, M.
A1 - Schoeckel, A.
A1 - Roth, C.
T1 - A combined in-situ XAS-DRIFTS study unraveling adsorbate induced changes on the Pt nanoparticle structure
N2 - The adsorption behavior of Platinum nanoparticles was studied for the as-received catalyst (under inert gas), under hydrogen and CO atmosphere using our newly designed in-situ cell. X-ray Absorption Spectroscopy (XAS) and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) experiments were performed simultaneously with high data quality. Structural information and the type of adsorbate could be revealed via Extended X-ray Absorption Fine Structure (EXAFS) analysis, Dl X-ray Absorption Near Edge Structure analysis (Dl XANES) and in-situ DRIFTS. The as-received catalyst showed sub-surface oxygen and O(n-fold). Under CO atmosphere only CO(atop) was found. Reversible adsorbate induced changes of the Pt nanoparticle structure were derived from changes in the PtAPt coordination number and the corresponding bond distance. Under reducing conditions (H2, CO) a significant increase in both values occurred. Temperature dependent desorption of CO revealed a gradual shift from PtACO to PtAO. Reoxidation was clearly assigned to strong metal support interaction from the SiO2 support.
KW - X-ray absorption spectroscopy
KW - DRIFTS
KW - XANES
KW - CO adsorption
KW - Platinum
KW - Strong metal support interaction
KW - Silica support
KW - Adsorbates
KW - Infrared spectroscopy
PY - 2016
DO - https://doi.org/10.1016/j.jcat.2016.03.034
IS - 339
SP - 57
EP - 67
PB - Elsevier Inc.
CY - Philadelphia, Pennsylvania, USA
AN - OPUS4-35815
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 - Lumpe, H.
A1 - Menke, Annika
A1 - Haisch, C.
A1 - Mayer, P.
A1 - Kabelitz, Anke
A1 - Yusenko, Kirill
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Block, T.
A1 - Pöttgen, R.
A1 - Emmerling, Franziska
A1 - Daumann, L.
T1 - The Earlier the Better: Structural Analysis and Separation of Lanthanides with Pyrroloquinoline Quinone
N2 - Lanthanides (Ln) are critical raw materials, however, their mining and purification have a considerable negative environmental impact and sustainable recycling and separation strategies for these elements are needed. In this study, the precipitation and solubility behavior of Ln complexes with pyrroloquinoline quinone (PQQ), the cofactor of recently discovered lanthanide (Ln) dependent methanol dehydrogenase (MDH) enzymes, is presented. In this context, the molecular structure of a biorelevant europium PQQ complex was for the first time elucidated outside a protein environment. The complex crystallizes as an inversion symmetric dimer, Eu2PQQ2, with binding of Eu in the biologically relevant pocket of PQQ. LnPQQ and Ln1Ln2PQQ complexes were characterized by using inductively coupled plasma mass spectrometry (ICP‐MS), infrared (IR) spectroscopy, 151Eu‐Mössbauer spectroscopy, X‐ray total scattering, and extended X‐ray absorption fine structure (EXAFS). It is shown that a natural enzymatic cofactor is capable to achieve separation by precipitation of the notoriously similar, and thus difficult to separate, lanthanides to some extent.
KW - PQQ
KW - Lanthanoide
KW - Coordination chemistry
KW - Rare earth elements separations
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-512707
DO - https://doi.org/10.1002/chem.202002653
VL - 26
IS - 44
SP - 10133
EP - 10139
AN - OPUS4-51270
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Smekhova, A.
A1 - Kuzmin, A.
A1 - Siemensmeyer, K.
A1 - Luo, C.
A1 - Taylor, J.
A1 - Thakur, S.
A1 - Radu, F.
A1 - Weschke, E.
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Xiao, B.
A1 - Savan, A.
A1 - Yusenko, Kirill
A1 - Ludwig, A.
T1 - Local structure and magnetic properties of a nanocrystalline Mn-rich Cantor alloy thin film down to the atomic scale
N2 - The huge atomic heterogeneity of high-entropy materials along with a possibility to unravel the behavior of individual components at the atomic scale suggests a great promise in designing new compositionally complex systems with the desired multi-functionality. Herein, we apply multi-edge X-ray absorption spectroscopy (extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES), and X-ray magnetic circular dichroism (XMCD)) to probe the structural, electronic, and magnetic properties of all individual constituents in the single-phase face-centered cubic (fcc)-structured nanocrystalline thin film of Cr20Mn26Fe18Co19Ni17 (at.%) high-entropy alloy on the local scale. The local crystallographic ordering and component-dependent lattice displacements were explored within the reverse Monte Carlo approach applied to EXAFS spectra collected at the K absorption edges of several constituents at room temperature. A homogeneous short-range fcc atomic environment around the absorbers of each type with very similar statistically averaged interatomic distances (2.54–2.55 Å) to their nearest-neighbors and enlarged structural relaxations of Cr atoms were revealed. XANES and XMCD spectra collected at the L2,3 absorption edges of all principal components at low temperature from the oxidized and in situ cleaned surfaces were used to probe the oxidation states, the changes in the electronic structure, and magnetic behavior of all constituents at the surface and in the sub-surface volume of the film. The spin and orbital magnetic moments of Fe, Co, and Ni components were quantitatively evaluated. The presence of magnetic phase transitions and the co-existence of different magnetic phases were uncovered by conventional magnetometry in a broad temperature range.
KW - Magnetism
KW - High-entropy alloys
KW - Reverse Monte Carlo (RMC)
KW - Element-specific spectroscopy
KW - Extended X-ray absorption fine structure (EXAFS),
KW - X-ray magnetic circular dichroism (XMCD),
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-578254
DO - https://doi.org/10.1007/s12274-022-5135-3
SN - 1998-0124
SP - 5626
PB - Springer
AN - OPUS4-57825
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Peters, Stefan
A1 - Kunkel, Benny
A1 - Cakir, Cafer Tufan
A1 - Kabelitz, Anke
A1 - Witte, Steffen
A1 - Bernstein, Thomas
A1 - Bartling, Stephan
A1 - Radtke, Martin
A1 - Emmerling, Franziska
A1 - Abdel-Mageed, Ali Mohamed
A1 - Wohlrab, Sebastian
A1 - de Oliveira Guilherme Buzanich, Ana
T1 - Time-, space- and energy-resolved in situ characterization of catalysts by X-ray absorption spectroscopy
N2 - A novel setup for dispersive X-ray absorption spectroscopy (XAS) with simultaneous resolution of space, time and energy for in situ characterization of solid materials is demonstrated.
KW - Dispersive XAS
KW - Catalysis
KW - In situ
KW - Structure analysis
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-584924
DO - https://doi.org/10.1039/d3cc03277a
SN - 1359-7345
SP - 1
EP - 4
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-58492
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Karafiludis, Stephanos
A1 - Ryll, T. W.
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Emmerling, Franziska
A1 - Stawski, Tomasz Maciej
T1 - Phase stability studies on transition metal phosphates aided by an automated synthesis
N2 - Transition metal phosphates (TMPs) have attracted interest as materials for (electro-) catalysis, and electrochemistry due to their low-cost, stability, and tunability. In this work, an automated synthesis platform was used for the preparation of transition metal phosphate crystals to efficiently explore the multidimensional parameter space, determining the phase selection, crystal sizes, shapes. By using X-ray diffraction and spectroscopy-based methods and electron microscopy imaging, a complete characterization of the phase stability fields, phase transitions, and crystal morphology/sizes was achieved. In an automated three-reactant synthesis, the individual effect of each reactant species NH4+, M2+, and PO43- on the formation of transition metal phosphate phases: M-struvite NH4MPO4·6H2O, M-phosphate octahydrate M3(PO4)2·8H2O with M = Ni, Co and an amorphous phase, was investigated. The NH4+ concentration dictates the phase composition, morphology, and particle size in the Ni-system (crystalline Ni-struvite versus amorphous Ni-PO4 phase), whereas in the Co-system all reactant species - NH4+, Co2+, and PO43- - influence the reaction outcome equivalently (Co-struvite vs. Co-phosphate octahydrate). The coordination environment for all crystalline compounds and of the amorphous Ni-PO4 phase was resolved by X-ray absorption spectroscopy, revealing matching characteristics to its crystalline analogue, Ni3(PO4)2·8H2O. The automated synthesis turned out to be significantly advantageous for the exploration of phase diagrams due to its simple modularity, facile traceability, and enhanced reproducibility compared to a typical manual synthesis.
KW - Automated synthesis
KW - Phase diagrams
KW - Transition metals
KW - Phosphates
KW - Local structure
KW - Struvite
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-579151
DO - https://doi.org/10.1039/D3CE00386H
VL - 25
IS - 30
SP - 4333
EP - 4344
PB - CrystEngComm
CY - London
AN - OPUS4-57915
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 - Heinekamp, Christian
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Ahrens, M.
A1 - Braun, T.
A1 - Emmerling, Franziska
T1 - An amorphous Lewis-acidic zirconium chlorofluoride as HF shuttle: C–F bond activation and formation
N2 - An exceptional HF transfer reaction by C–F bond activation of fluoropentane and a subsequent hydrofluorination of alkynes at room temperature is reported. An amorphous Lewis-acidic Zr chlorofluoride serves as heterogeneous catalyst, which is characterised by an eightfold coordination environment at Zr including chlorine atoms. The studies are seminal in establishing sustainable fluorine chemistry.
KW - ZCF
KW - Heterogeneous catalysis
KW - C-F bond activation
KW - HF-shuttle
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-582249
DO - https://doi.org/10.1039/D3CC03164K
SN - 1359-7345
VL - 59
IS - 75
SP - 11224
EP - 11227
PB - RSC
CY - Cambridge
AN - OPUS4-58224
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Coburger, Peter
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Emmerling, Franziska
A1 - Abbenseth, Josh
T1 - Combining geometric constraint and redox non-innocence within an ambiphilic PBiP pincer ligand
N2 - The first pincer ligand featuring a strictly T-shaped pnictogen donor moiety was synthesised. The PBiP ligand's redox activity facilitates unprecedented ambiphilic bonding of the Bi centre with transition metals through the Bi(6p) orbital.
KW - EXAFS
KW - Pincer Ligand
KW - Group 15 metals
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-611113
DO - https://doi.org/10.1039/D4SC00197D
SN - 2041-6520
SP - 1
EP - 8
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-61111
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Heilmann, Maria
A1 - Prinz, Carsten
A1 - Bienert, Ralf
A1 - Wendt, R.
A1 - Kunkel, B.
A1 - Radnik, Jörg
A1 - Hoell, A.
A1 - Wohlrab, S.
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Emmerling, Franziska
T1 - Size-Tunable Ni–Cu Core–Shell Nanoparticles—Structure, Composition, and Catalytic Activity for the Reverse Water–Gas Shift Reaction
N2 - A facile and efficient methodology is described for the solvothermal synthesis of size-tunable, stable, and uniform NiCu core–shell nanoparticles (NPs) for application in catalysis. The diameter of the NPs is tuned in a range from 6 nm to 30 nm and to adjust the Ni:Cu ratio from 30:1 to 1:1. Furthermore, the influence of different reaction parameters on the final NPs is studied. The NPs are structurally characterized by a method combination of transmission electron microscopy, anomalous small-angle X-ray scattering, X-ray absorption fine structure, and X-ray photoelectron spectroscopy. Using these analytical methods, it is possible to elucidate a core–shell–shell structure of all particles and their chemical composition. In all cases, a depletion from the core to the shell is observed, with the core consisting of NiCu alloy, surrounded by an inner Ni-rich shell and an outer NiO shell. The SiO2-supported NiCu core–shell NPs show pronounced selectivity of >99% for CO in the catalytic reduction of CO2 to CO using hydrogen as reactant (reverse water–gas shift reaction) independent of size and Ni:Cu ratio.
KW - Nanoparticles
KW - Core-shell
KW - Catalysis
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543606
DO - https://doi.org/10.1002/adem.202101308
SN - 1438-1656
SP - 1
EP - 13
PB - Wiley VCH
AN - OPUS4-54360
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Wahl, S.
A1 - El-Refaei, S. M.
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Amsalem, P.
A1 - Lee, K.-S.
A1 - Koch, N.
A1 - Doublet, M.-L.
A1 - Pinna, N.
T1 - Zn0.35Co0.65O – A Stable and highly active oxygen evolution catalyst formed by zinc leaching and tetrahedral coordinated cobalt in wurtzite structure
N2 - To arrive to sustainable hydrogen-based energy solutions, the understanding of water-splitting catalysts plays the most crucial role. Herein, state-of-the-art hypotheses are combined on electrocatalytic active metal sites toward the oxygen evolution reaction (OER) to develop a highly efficient catalyst based on Earth-abundant cobalt and zinc oxides.
The precursor catalyst Zn0.35Co0.65O is synthesized via a fast microwaveassisted approach at low temperatures. Subsequently, it transforms in situ from the wurtzite structure to the layered γ-Co(O)OH, while most of its zinc leaches out. This material shows outstanding catalytic Performance and stability toward the OER in 1 m KOH (overpotential at 10 mA cm−2 ηinitial = 306 mV, η98 h = 318 mV). By comparing the electrochemical results and ex situ analyses to today’s literature, clear structureactivity correlations are able to be identified. The findings suggest that coordinately unsaturated cobalt octahedra on the surface are indeed the active centers for the OER.
KW - Oxygen Evolution Catalyst
KW - XAFS
KW - Oxygen evolution reaction (OER)
KW - Cobalt and zinc oxides
PY - 2019
DO - https://doi.org/10.1002/aenm.201900328
SN - 1614-6832
SN - 1614-6840
VL - 9
IS - 20
SP - 1900328,1
EP - 10
PB - WILEY-VCH Verlag GmbH & Co. KGaA
CY - Weinheim
AN - OPUS4-48200
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - de Oliveira Guilherme Buzanich, Ana
T1 - Hard X-ray spectroscopy and imaging at the BAMline and MySpot beamlines at BESSY II (Berlin, Germany)
N2 - Overview of the X-ray based analytical methods conducted at the BAMline and µSpot Beamline for structure analysis.
T2 - Pccr2 + AfLS conference
CY - Accra, Ghana
DA - 29.01.2019
KW - X-ray spectroscopy
KW - Synchrotron
KW - Beamline
KW - Material characterization
PY - 2019
AN - OPUS4-47319
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kulow, Anicó
A1 - Witte, S.
A1 - Beyer, S.
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Radtke, Martin
A1 - Reinholz, Uwe
A1 - Riesemeier, H.
A1 - Streli, C.
T1 - A new experimental setup for time- and laterally-resolved X-ray absorption fine structure spectroscopy in a 'single shot'
N2 - In this work, a new setup for dispersive XAFS measurements is presented. This reproducible and scanningfree setup yields both time- and laterally-resolved XAFS experiments in a ‘single-shot’. It allows a straightforward adjustment for probing different elements covering many relevant applications in materials science. An incoming energetic broadband beam is diffracted by a Si (111) crystal after passing through the sample and collected by an area sensitive detector. Depending on the energy range of the incoming beam, XANES and/or EXAFS spectra can be recorded with a time resolution down to 1 s. The feasibility of this setup was demonstrated at the BAMline at BESSY II (Berlin, Germany) with reference Fe and Cu foils and the results are hereby presented and discussed. Additionally, an application where time resolution on the second scale is required is briefly evaluated. The presented example concerns studying early stages of zinc(II)2-methylimidazolate (ZIF-8) crystallization. This is particularly important for biomedical applications.
KW - X-ray spectroscopy
KW - X-ray absorption fine structure
KW - Time-resolved
KW - Laterally-resolved
KW - Experimental setup
PY - 2019
DO - https://doi.org/10.1039/c8ja00313k
SN - 0267-9477
SN - 1364-5544
VL - 34
IS - 1
SP - 239
EP - 246
PB - Royal Society of Chemistry
CY - London
AN - OPUS4-47207
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - de Oliveira Guilherme Buzanich, Ana
T1 - Career talk & lab tour - Working at BESSY II, a large scale research facility in Adlershof
N2 - What exactly does a postdoc do at a research institute? What scientific questions does he or she want to address? What is their daily work routine? During our regular Lab Tours, female postdocs provide insight into their jobs. They also tell us about their career path: How did they get there? And what do they envision for their professional future?
This time, Dr. Ana Guilherme Buzanich, a scientist from the Structure Analysis division at the Bundesanstalt für Materialforschung und -prüfung (BAM), will give an overview of her Research areas. She works at the electron storage ring BESSY-II where she conducts experiments at two hard X-ray beamlines (BAMline and µSpot). The tour includes a guided visit of the research facility.
T2 - Lab Tour & Career Talk, WiNS
CY - Berlin, Germany
DA - 11.02.2019
KW - Women in STEM
KW - X-ray Spectroscopy
KW - Synchrotron
KW - Beamline
KW - Material characterization
PY - 2019
AN - OPUS4-47418
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Abad Andrade, Carlos Enrique
A1 - Florek, S.
A1 - Becker-Ross, H.
A1 - Huang, M.-D.
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Radtke, Martin
A1 - Lippitz, Andreas
A1 - Hodoroaba, Vasile-Dan
A1 - Schmid, Thomas
A1 - Heinrich, Hans-Joachim
A1 - Recknagel, Sebastian
A1 - Jakubowski, Norbert
A1 - Panne, Ulrich
T1 - Zirconium permanent modifiers for graphite furnaces used in absorption spectrometry: understanding their structure and mechanism of action
N2 - The mechanism of action of zirconium permanent modifiers on graphite surfaces was investigated in order to understand its influence on the analytical signal in atomic and molecular absorption spectrometry (AAS/MAS). For this, the molecule formation of CaF was studied, which is used for the indirect analytical determination of fluorine in high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). The kinetics of this reaction was established by monitoring its molecular spectrum at different atomisation temperatures. An Arrhenius plot showed a pseudo-first order reaction with respect to fluorine (n = 1). An intermediate state was isolated, and its structure was elucidated by spectroscopic methods: scanning electron microscopy with energy dispersive X-ray spectroscopy (SEMEDX), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XANES and EXAFS), and Raman microspectroscopy. We propose here a mechanism, where ZrO2 acts as a heterogeneous catalyst: after a pyrolytic step, an intermediate state of ZrO(OCaF) is activated, and at higher temperatures, CaF(g) is released from the zirconium-coated graphite surface. No evidence of the formation of zirconium carbide was found. Consequently, as the CaF formation is catalysed by a heterogeneous catalyst, surface modifications with ZrO2 nanoparticles and ZrO xerogels were investigated in order to increase the surface area. Their influence was evaluated in the molecule formation of CaF, CaCl, CaBr, and CaI. Graphite furnace modification with zirconium oxide nanoparticles proves to be the best choice for fluorine analysis with a signal enhancement of more than eleven times with respect a non-coated graphite furnace. However, the influence of zirconium modifications in the analytical signals of Cl, and I is lower than the F signals or even negative in case of the Br. Understanding zirconium modifiers as heterogeneous catalysts offers a new perspective to AAS and MAS, and reveals the potential of surface analytical methods for development of improved permanent modifiers and graphite furnace coatings.
KW - Zirconium
KW - HR-CS-MAS
KW - Graphite furnace
KW - Nanoparticles
KW - Xerogel
KW - Calcium monofluoride
KW - Absorption spectrometry
PY - 2018
UR - https://pubs.rsc.org/en/content/articlelanding/2018/ja/c8ja00190a
DO - https://doi.org/10.1039/C8JA00190A
SN - 0267-9477
VL - 33
IS - 12
SP - 2034
EP - 2042
PB - Royal Society of Chemistry
AN - OPUS4-46775
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weber, Kathrin
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Radtke, Martin
A1 - Reinholz, Uwe
A1 - Stephan-Scherb, Christiane
T1 - A µ‐XANES study of the combined oxidation/sulfidation of Fe–Cr model alloys
N2 - The precise analysis of cation diffusion profiles through corrosion scales is an important aspect to evaluate corrosion phenomena under multicomponent chemical load, as during high‐temperature corrosion under deposits and salts. The present study shows a comprehensive analysis of cation diffusion profiles by electron microprobe analysis and microbeam X‐ray absorption near edge structure (µ‐XANES) spectroscopy in mixed oxide/sulfide scales grown on Fe–Cr model alloys after exposing them to 0.5% SO2. The results presented here correspond to depth‐dependent phase identification of oxides and sulfides in the corrosion scales by µ‐XANES and the description of oxidation‐state‐dependent diffusion profiles. Scales grown on low‐ and high‐alloyed materials show both a well‐pronounced diffusion profile with a high concentration of Fe3+ at the gas and a high concentration of Fe2+ at the alloy interface. The distribution of the cations within a close‐packed oxide lattice is strongly influencing the lattice diffusion phenomena due to their different oxidation states and therefore different crystal‐field preference energies. This issue is discussed based on the results obtained by µ‐XANES analysis.
KW - X-ray absorption spectroscopy
KW - Oxidation
KW - Sulfidation
PY - 2019
DO - https://doi.org/10.1002/maco.201810644
VL - 70
IS - 8
SP - 1360
EP - 1370
PB - Wiley VCH-Verlag
AN - OPUS4-47934
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Gao, S.
A1 - Hou, J.
A1 - Deng, Z.
A1 - Wang, T.
A1 - Beyer, Sebastian
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Richardson, J. J.
A1 - Rawal, A.
A1 - Seidel, R.
A1 - Zulkifli, M. Y.
A1 - Li, W.
A1 - Bennett, T. D.
A1 - Cheetham, A. K.
A1 - Liang, K.
T1 - Improving the Acidic Stability of Zeolitic Imidazolate Frameworks by Biofunctional Molecules
N2 - Zeolitic imidazolate frameworks (ZIFs) have been widely investigated for their use in separation, gas adsorption, catalysis, and biotechnology. Their practical applications, however, can be hampered by their structural instability in humid acidic conditions. Here, guided by density functional theory calculations, we demonstrate that the acidic stability of two polymorphic ZIFs (i.e., ZIF-8 and ZIF-L) can be enhanced by the incorporation of functional groups on polypeptides or DNA. A range of complementary synchrotron investigations into the local chemical structure and bonding environment suggest that the enhanced acidic stability arises from the newly established coordinative interactions between the Zn centers and the inserted carboxylate (for polypeptides) or phosphate (for DNA) groups, both of which have lower pKas than the imidazolate ligand. With functional biomolecular homologs (i.e., enzymes), we demonstrate a symbiotic stability reinforcement effect, i.e., the encapsulated biomolecules stabilize the ZIF matrix while the ZIF exoskeleton protects the enzyme from denaturation.
KW - Zeolitic Imidazolate Frameworks
KW - Biofunctional Molecules
KW - X-ray Absorption Spectroscopy
PY - 2019
DO - https://doi.org/10.1016/j.chempr.2019.03.025
VL - 5
IS - 6
SP - 1597
EP - 1608
PB - Elsevier Inc.
AN - OPUS4-48702
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - de Oliveira Guilherme Buzanich, Ana
T1 - Structure analytics with Hard X-rays at the BAMline and µSpot beamlines
N2 - An overview of the research areas at the structure analysis division is given. Specifically the in situ characterization of dynamic processes with hard X-ray diffraction and absorption spectroscopy at the BAMline and µSpot beamlines (BESSY-II).
T2 - BAM-IFW Workshop
CY - Dresden, Germany
DA - 28.03.2019
KW - Structure analysis
KW - X-ray Spectroscopy
KW - Synchrotron
KW - Beamline
KW - Material characterization
PY - 2019
AN - OPUS4-47695
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Manso, M.
A1 - Pessanha, S.
A1 - Guerra, M.
A1 - Reinholz, Uwe
A1 - Afonso, C.
A1 - Radtke, Martin
A1 - Lourenco, H.
A1 - Carvalho, M. L.
A1 - de Oliveira Guilherme Buzanich, Ana
T1 - Assessment of Toxic Metals and Hazardous Substances in Tattoo Inks Using Sy-XRF, AAS, and Raman Spectroscopy
N2 - Synchrotron radiation X-ray fluorescence spectroscopy, in conjunction with atomic absorption and Raman spectroscopy, was used to analyze a set of top brand tattoo inks to investigate the presence of toxic elements and hazardous substances. The Cr, Cu, and Pb contents were found to be above the maximum allowed levels established by the Council of Europe through the resolution ResAP(2008)1 on requirements and criteria for the safety of tattoos and permanent makeup. Raman analysis has revealed the presence of a set of prohibited substances mentioned in ResAP(2008)1, among which are the pigments Blue 15, Green 7, and Violet 23. Other pigments that were identified in white, black, red, and yellow inks are the Pigment White 6, Carbon Black, Pigment Red 8, and a diazo yellow, respectively. The present results show the importance of regulating tattoo ink composition.
KW - Synchrotron
KW - Tattoo inks
KW - XRF
KW - Toxic metals
KW - Hazardous substances
PY - 2019
DO - https://doi.org/10.1007/s12011-018-1406-y
VL - 187
IS - 2
SP - 596
EP - 601
PB - Springer
AN - OPUS4-47369
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Karafiludis, Stephanos
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Heinekamp, Christian
A1 - Smales, Glen Jacob
A1 - Hodoroaba, Vasile-Dan
A1 - ten Elshof, J. E.
A1 - Emmerling, Franziska
A1 - Stawski, Tomasz
T1 - Template-free synthesis of mesoporous, amorphous transition metal phosphate materials
N2 - We present how mesoporosity can be engineered in transition metal phosphate (TMPs) materials in a template-free manner. The method involves a transformation of a precursor metal phosphate phase, called M-struvite (NH4MPO4·6H2O, M = Mg2+, Ni2+, Co2+, NixCo1-x2+). It relies on the thermal decomposition of crystalline M-struvite precursors to an amorphous and simultaneously mesoporous phase, which forms while degassing of NH3 and H2O. The temporal evolution of mesoporous frameworks and the response of the metal coordination environment were followed with in-situ and ex-situ scattering and diffraction, as well as X -ray spectroscopy. Despite sharing the same precursor struvite structure, different amorphous and mesoporous structures were obtained depending on the involved transition metal. We highlight the systematic differences in absolute surface area, pore shape, pore size, and phase transitions depending on a metal cation present in the analogous M-struvites. The amorphous structures of thermally decomposed Mg-, Ni- and NixCo1-x-struvites exhibit high surface areas and pore volumes (240 m²g-1 and 0.32 cm-3 g-1 for Mg and 90 m²g-1 and 0.13 cm-3 g-1 for Ni). We propose that the low-cost, environmentally friendly M-struvites could be obtained as recycling products from industrial and agricultural wastewaters. These waste products could be then upcycled into mesoporous TMPs through a simple thermal treatment for further applications, for instance, in (electro)catalysis.
KW - Struvite
KW - Pphosphates
KW - Transition metal
KW - In-situ SAXS/WAXS
KW - Mesoporosity
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569503
DO - https://doi.org/10.1039/D2NR05630E
SN - 2040-3364
SP - 1
EP - 15
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-56950
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 - Karafiludis, Stephanos
A1 - Bhattacharya, Biswajit
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Fink, Friedrich
A1 - Feldmann, Ines
A1 - ten Elshof, J. E.
A1 - Emmerling, Franziska
A1 - Stawski, Tomasz
T1 - Thermally processed Ni-and Co-struvites as functional materials for proton conductivity
N2 - We present how mesoporosity can be engineered in transition metal phosphate (TMPs) materials in a template-free manner. The method involves the transformation of a precursor metal phosphate phase, called M-struvite (NH4MPO4·6H2O, M = Mg2+, Ni2+, Co2+, NixCo1−x2+). It relies on the thermal decomposition of crystalline M-struvite precursors to an amorphous and simultaneously mesoporous phase, which forms during degassing of NH3 and H2O. The temporal evolution of mesoporous frameworks and the response of the metal coordination environment were followed by in situ and ex situ scattering and diffraction, as well as X-ray spectroscopy. Despite sharing the same precursor struvite structure, different amorphous and mesoporous structures were obtained depending on the involved transition metal. We highlight the systematic differences in absolute surface area, pore shape, pore size, and phase transitions depending on the metal cation present in the analogous M-struvites. The amorphous structures of thermally decomposed Mg-, Ni- and NixCo1−x-struvites exhibit high surface areas and pore volumes (240 m2 g−1 and 0.32 cm−3 g−1 for Mg and 90 m2 g−1 and 0.13 cm−3 g−1 for Ni). We propose that the low-cost, environmentally friendly M-struvites could be obtained as recycling products from industrial and agricultural wastewaters. These waste products could be then upcycled into mesoporous TMPs through a simple thermal treatment for further application, for instance in (electro)catalysis.
KW - Struvite
KW - Phosphates
KW - Transition metals
KW - Proton conductivity
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-575862
DO - https://doi.org/10.1039/D3DT00839H
SN - 1477-9226
SP - 1
EP - 13
PB - Royal Society of Chemisty (RSC)
CY - London/Cambridge
AN - OPUS4-57586
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Karafiludis, Stephanos
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Kochovski, Z.
A1 - Feldmann, Ines
A1 - Emmerling, Franziska
A1 - Stawski, Tomasz
T1 - Ni- and Co-Struvites: Revealing Crystallization Mechanisms and Crystal Engineering toward Applicational Use of Transition Metal Phosphates
N2 - Industrial and agricultural waste streams (waste water, sludges, tailings, etc.) which contain high concentrations of NH4+, PO43–, and transition metals are environmentally harmful and toxic pollutants. At the same time, phosphorous and transition metals constitute highly valuable resources. Typically, separate pathways have been considered to extract hazardous transition metals or phosphate independently from each other. Investigations on the simultaneous removal of multiple components have been carried out only to a limited extent. Here, we report the synthesis routes for Ni- and Co-struvites (NH4MPO4·6H2O, M = Ni2+ and Co2+), which allow for P, ammonia, and metal co-precipitation. By evaluating different reaction parameters, the phase and stability of transition metal struvites as well as their crystal morphologies and sizes could be optimized. Ni-struvite is stable in a wide reactant concentration range and at different metal/phosphorus (M/P) ratios, whereas Co-struvite only forms at low M/P ratios. Detailed investigations of the precipitation process using ex situ and in situ techniques provided insights into the crystallization mechanisms/crystal engineering of these materials. M-struvites crystallize via intermediate colloidal amorphous nanophases, which subsequently aggregate and condense to final crystals after extended reaction times. However, the exact reaction kinetics of the formation of a final crystalline product varies significantly depending on the involved metal cation in the precipitation process: several seconds (Mg) to minutes (Ni) to hours (Co). The achieved level of control over the morphology and size makes precipitation of transition metal struvites a promising method for direct metal recovery and binding them in the form of valuable phosphate raw materials. Under this paradigm, the crystals can be potentially up-cycled as precursor powders for electrochemical or (electro)catalytic applications, which require transition metal phosphates.
KW - Crystallization
KW - Struvite
KW - Nickel
KW - Cobalt
KW - Phosphorous recovery
KW - Up-cycling
KW - Aqueous synthesis
PY - 2022
DO - https://doi.org/10.1021/acs.cgd.2c00284
VL - 22
IS - 7
SP - 4305
EP - 4315
PB - ACS Publications
CY - Washington D.C.
AN - OPUS4-55286
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Roy, Arkendu
A1 - Kumar, Sourabh
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Prinz, Carsten
A1 - Götz, Emilia
A1 - Retzmann, Anika
A1 - Hickel, Tilmann
A1 - Bhattacharya, Biswajit
A1 - Emmerling, Franziska
T1 - Synergistic Catalytic Sites in High‐Entropy Metal Hydroxide Organic Framework for Oxygen Evolution Reaction
N2 - AbstractThe integration of multiple elements in a high‐entropy state is crucial in the design of high‐performance, durable electrocatalysts. High‐entropy metal hydroxide organic frameworks (HE‐MHOFs) are synthesized under mild solvothermal conditions. This novel crystalline metal–organic framework (MOF) features a random, homogeneous distribution of cations within high‐entropy hydroxide layers. HE‐MHOF exhibits excellent electrocatalytic performance for the oxygen evolution reaction (OER), reaching a current density of 100 mA cm−2 at ≈1.64 VRHE, and demonstrates remarkable durability, maintaining a current density of 10 mA cm−2 for over 100 h. Notably, HE‐MHOF outperforms precious metal‐based electrocatalysts despite containing only ≈60% OER active metals. Ab initio calculations and operando X‐ray absorption spectroscopy (XAS) demonstrate that the high‐entropy catalyst contains active sites that facilitate a multifaceted OER mechanism. This study highlights the benefits of high‐entropy MOFs in developing noble metal‐free electrocatalysts, reducing reliance on precious metals, lowering metal loading (especially for Ni, Co, and Mn), and ultimately reducing costs for sustainable water electrolysis technologies.
KW - Electrocatalysis
KW - Green Hydrogen
PY - 2024
DO - https://doi.org/10.1002/adma.202408114
SP - 1
EP - 14
PB - Wiley
AN - OPUS4-61739
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Yao, Xingyu
A1 - Antunes, Margarida M.
A1 - Guilherme Buzanich, Ana
A1 - Cabanelas, Pedro
A1 - Valente, Anabela A.
A1 - Pinna, Nicola
A1 - Russo, Patrícia A.
T1 - Formation, Phase Transition, Surface, and Catalytic Properties of Cubic ZrO 2 Nanocrystals
N2 - Pseudocapacitance-type transition metal oxides have been extensively investigated as anodes for lithium-ion batteries (LIBs). Currently, they are also gaining attention for sodium-ion batteries (SIBs) due to their low volume change and safety. However, their performance in sodium storage remains limited, primarily due to the larger Na+ ion radius. Here, for the first time, an iron niobate is reported with a columbite structure as a high-Performance sodium storage anode. The presence of iron triggers the loss of long-rangeorder through disorder of the FeO6 octahedra local structure, subsequentlyallowing reversible sodium storage in an amorphous phase. Simultaneously, the formation of short-range ordered zigzag-chain structures within the NbO6 planes creates a “skeleton” that offers abundant active sites forpseudocapacitive ion storage and enhanced ion diffusion pathways. These characteristics of FeNb2O6 make it an effective intercalation host, offering high capacity along with fast Na+ kinetics, as demonstrated through operando and ex situ characterizations. It leads to an applicable reversible capacity (>300 mAh g−1) with a favorable average voltage of ≈0.6 V and excellent rate capability (180.4 mAh g−1 at a current density of 2 A g−1). This study provides insights into the development of intrinsically active transition metal oxides for Na+-ion intercalation.
KW - XAS
KW - Sodium-ion Batteries
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-654955
DO - https://doi.org/10.1021/acs.chemmater.5c01483
SN - 0897-4756
VL - 37
IS - 21
SP - 8568
EP - 8580
PB - American Chemical Society (ACS)
AN - OPUS4-65495
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Faustino, Leandro A.
A1 - de Angelis, Leonardo D.
A1 - de Melo, Eduardo C.
A1 - Farias, Giliandro
A1 - dos Santos, Egon C.
A1 - Miranda, Caetano R.
A1 - Buzanich, Ana G.
A1 - Torresi, Roberto M.
A1 - de Oliveira, Paulo F.M.
A1 - Córdoba de Torresi, Susana I.
T1 - Urea synthesis by Plasmon-Assisted N2 and CO2 co-electrolysis onto heterojunctions decorated with silver nanoparticles
N2 - The N2 + CO2 co-electrolysis to urea synthesis has become a promising alternative to the energy intensive traditional processes for urea production. However, there are still challenges in this approach, especially due to the competition with HER (Hydrogen Evolution Reaction) leading to low efficiency. Electrochemistry assisted by localized surface plasmon resonance (LSPR) using metal nanoparticles has been reported to enhance different electrochemical reactions. Here we report an electrochemical LSPR assisted urea synthesis using Ag nanoparticles (NPs) supported on BiVO4/BiFeO3 catalyst mechanochemically synthesized. The electrochemical experiments were performed under dark and upon plasmon excitation at the LSPR region of Ag NPs. Our results demonstrated that exciting in the LSPR range, urea yield rate and Faradic efficiency were considerably improved with reduced overpotential, 19.2 μmol h− 1 g− 1 and FE 24.4% at +0.1 V vs RHE compared to 9.6 μmol h− 1 g− 1 and FE 9.4% at − 0.2 V vs RHE under dark conditions. Further in situ FTIR-RAS experiments for mechanism investigation revealed the presence of N-H and C-N intermediates and the real effect of Ag plasmon excitation on HER and N2 + CO2 co-electrolysis. Theoretical calculations confirm the energy of the species involved in C-N coupling as well the role of the complex catalytic sites, which agrees with XAS measurements.
KW - Plasmon-assited
KW - XAS
KW - Urea
KW - Electrocatalysis
PY - 2025
DO - https://doi.org/10.1016/j.cej.2025.163072
SN - 1385-8947
VL - 513
SP - 1
EP - 13
PB - Elsevier B.V.
AN - OPUS4-65492
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Pavlidis, Sotirios
A1 - Fischer, Eric W.
A1 - Opis-Basilio, Amanda
A1 - Bera, Ayan
A1 - Guilherme Buzanich, Ana
A1 - Álvarez-Sánchez, María
A1 - Wittek, Severin
A1 - Emmerling, Franziska
A1 - Ray, Kallol
A1 - Roemelt, Michael
A1 - Abbenseth, Josh
T1 - Ambiphilic Reactivity and Switchable Methyl Transfer at a T-Shaped Bi(NNN) Complex Enabled by a Redox-Active Pincer Ligand
N2 - We report the transition-metal-like reactivity of a geometrically constrained, ambiphilic bismuth(III) trisamide. Planarization of the Bi(III) center unlocks Bi−C bond formation when reacted with mild electrophiles (alkyl iodides and triflates) accompanied by two-electron oxidation of the utilized NNN pincer nligand. The preservation of the bismuth oxidation state is confirmed by single-crystal X-ray diffraction and X-ray absorption spectroscopy and corroborated by theoretical calculations. Sequential reduction of the oxidized ligand framework alters the reactivity of a generated Bi−Me unit, enabling controlled access to methyl cation, radical, and anion equivalents. The full [Bi(Me)(NNN)]+/•/− redox series was comprehensively characterized using NMR and EPR spectroscopy as well as spectro-electrochemistry. This work represents the first example of ligand-assisted, redox-neutral C−X bond splitting at bismuth, establishing a new paradigm for synthetic bismuth chemistry.
KW - Pincer ligand
KW - XAS
KW - Redox
PY - 2026
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-654948
DO - https://doi.org/10.1021/jacs.5c18955
SN - 0002-7863
VL - 148
IS - 2
SP - 2683
EP - 2692
PB - American Chemical Society (ACS)
AN - OPUS4-65494
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Liu, Yanchen
A1 - Guilherme Buzanich, Ana
A1 - Alippi, Paola
A1 - Montoro, Luciano A.
A1 - Lee, Kug‐Seung
A1 - Jeon, Taeyeol
A1 - Weißer, Kilian
A1 - Karlsen, Martin A.
A1 - Russo, Patrícia A.
A1 - Pinna, Nicola
T1 - FeNb 2 O 6 as a High‐Performance Anode for Sodium‐Ion Batteries Enabled by Structural Amorphization Coupled with NbO 6 Local Ordering
N2 - Pseudocapacitance-type transition metal oxides have been extensively investigated as anodes for lithium-ion batteries (LIBs). Currently, they are also gaining attention for sodium-ion batteries (SIBs) due to their low volume change and safety. However, their performance in sodium storage remains limited, primarily due to the larger Na+ ion radius. Here, for the first time, an iron niobate is reported with a columbite structure as a high-performance sodium storage anode. The presence of iron triggers the loss of long-range order through disorder of the FeO6 octahedra local structure, subsequently allowing reversible sodium storage in an amorphous phase. Simultaneously, the formation of short-range ordered zigzag-chain structures within the NbO6 planes creates a “skeleton” that offers abundant active sites for pseudocapacitive ion storage and enhanced ion diffusion pathways. These characteristics of FeNb2O6 make it an effective intercalation host, offering high capacity along with fast Na+ kinetics, as demonstrated through operando and ex situ characterizations. It leads to an applicable reversible capacity (>300 mAh g−1) with a favorable average voltage of ≈0.6 V and excellent rate capability (180.4 mAh g−1 at a current density of 2 A g−1). This study provides insights into the development of intrinsically active transition metal oxides for Na+-ion intercalation.
KW - SIB
KW - XAS
KW - Sodium-ion Batteries
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-654931
DO - https://doi.org/10.1002/adma.202504100
SN - 0935-9648
VL - 37
IS - 46
SP - 1
EP - 13
PB - Wiley
AN - OPUS4-65493
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Bustos, Jenna
A1 - Shohel, Mohammad
A1 - Guilherme Buzanich, Ana
A1 - Zakharov, Lev
A1 - Buils, Jordi
A1 - Segado‐Centellas, Mireia
A1 - Bo, Carles
A1 - Nyman, May
T1 - Technetium and Rhenium Auto‐reduction, Polymerization and Lability towards Group VII Polyoxometalate Chemistry
N2 - AbstractGroup VII Tc and Re have long been studied to develop both radiopharmaceuticals and technologies for nuclear materials management. Fundamental research has targeted understanding this periodic table crossroads where polyoxometalates meets metal‐metal bonded complexes. Here we have isolated green hygroscopic and metastable crystals of (ReVI,oct)2(ReVII,tet)2(OH)2(O)12⋅H2O (ReVI,VII‐green, tet=tetrahedral, oct=octahedral), determined by single‐crystal x‐ray diffraction. In addition to color, Re‐L1 X‐ray absorption near‐edge spectroscopy confirms the reduced oxidation state. ReVI,VII‐green provides the first demonstration of Re autoreduction, long‐observed for Mn and Tc. We also isolated and structurally characterized [Tc4O4(H2O)2(ReO4)14]2− (Tc4Re14) polyanion crystals that contain Tc(V) and Re(VII), consistent with greater stability of reduced Tc compared to reduced Re. Small angle X‐ray scattering of both compounds and prior‐reported polyanion [Tc4O4(H2O)2(TcO4)14]4− (Tc20) dissolved in acetonitrile indicated a qualitative lability order of oxo‐linkages of Re‐O−Re Re‐O−Tc Tc‐O−Tc, and lability of Tc20 was also probed by 99Tc nuclear magnetic resonance spectroscopy. Computation provided insight into 99Tc chemical shifts as well as lability. Based on both reducibility and solution phase dynamics of polynuclear compounds investigated here, Re is an imperfect surrogate for Tc, and further expansion of group VII polyoxometalate chemistry seems promising.
KW - XANES
KW - Polyoxometalate
KW - Technetium
PY - 2025
DO - https://doi.org/10.1002/chem.202404144
SN - 0947-6539
VL - 31
IS - 21
SP - 1
EP - 7
PB - Wiley-VCH Verl.
AN - OPUS4-65491
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Martins, Ines
A1 - Al-Sabbagh, Dominik
A1 - Bentrup, U.
A1 - Marquardt, Julien
A1 - Schmid, Thomas
A1 - Scoppola, E.
A1 - Kraus, Werner
A1 - Stawski, Tomasz
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Yusenko, Kirill
A1 - Weidner, Steffen
A1 - Emmerling, Franziska
T1 - Formation Mechanism of a Nano-Ring of Bismuth Cations and Mono-Lacunary Keggin-Type Phosphomolybdate
N2 - A new hetero-bimetallic polyoxometalate (POM) nano-ring was synthesized in a one-pot procedure. The structure consists of tetrameric units containing four bismuth-substituted monolacunary Keggin anions including distorted [BiO8] cubes. The nano-ring is formed via self-assembly from metal precursors in aqueous acidic medium. The compound (NH4)16[(BiPMo11O39)4] ⋅ 22 H2O; (P4Bi4Mo44) was characterized by single-crystal X-ray diffraction, extended X-ray absorption fine structure spectroscopy (EXAFS), Raman spectroscopy, matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF), and thermogravimetry/differential scanning calorimetry mass spectrometry (TG-DSC-MS). The formation of the nano-ring in solution was studied by time-resolved in situ small- and wide-angle X-ray scattering (SAXS/WAXS) and in situ EXAFS measurements at the Mo−K and the Bi−L3 edge indicating a two-step process consisting of condensation of Mo-anions and formation of Bi−Mo-units followed by a rapid self-assembly to yield the final tetrameric ring structure.
KW - Bismuth
KW - In situ EXAFS
KW - In situ SAXS/WAXS
KW - Lacunary Keggin ion
KW - Polyoxometalates
KW - Self-assembly
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546823
DO - https://doi.org/10.1002/chem.202200079
SN - 0947-6539
VL - 28
IS - 27
SP - 1
EP - 7
PB - Wiley-VCH
CY - Weinheim
AN - OPUS4-54682
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -