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 - 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 - 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 - 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 -
TY - JOUR
A1 - Menga, D.
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Wagner, F.
A1 - Fellinger, Tim-Patrick
T1 - Evaluation of the Specific Activity of MNCs and the Intrinsic Activity of Tetrapyrrolic FeN4 Sites for the Oxygen Reduction Reaction
N2 - M−N−C electrocatalysts are considered pivotal to replace expensive precious group metal-based materials in electrocatalytic conversions. However, their development is hampered by the limited availability of methods for the evaluation of the intrinsic activity of different active sites, like pyrrolic FeN4 sites within Fe−N−Cs. Currently, new synthetic procedures based on active-site imprinting followed by an ion exchange reaction, e.g. Zn-to-Fe, are producing single-site M−N−Cs with outstanding activity. Based on the same replacement principle, we employed a conservative iron extraction to partially remove the Fe ions from the N4 cavities in Fe−N−Cs. Having catalysts with the same morphological properties and Fe ligation that differ solely in Fe content allows for the facile determination of the decrease in density of active sites and their turn-over frequency. In this way, insight into the specific activity of M−N−Cs is obtained and for single-site catalysts the intrinsic activity of the site is accessible. This new approach surpasses limitations of methods that rely on probe molecules and, together with those techniques, offers a novel tool to unfold the complexity of Fe−N−C catalyst and M−N−Cs in general.
KW - Fe-N-C catalysts
KW - M-N-C catalysts
KW - Fuel Cells
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-567406
DO - https://doi.org/10.1002/anie.202207089
SN - 1433-7851
VL - 61
IS - 50
SP - 1
EP - 6
PB - Wiley-VHC
AN - OPUS4-56740
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 -