TY - JOUR A1 - Mino, L. A1 - Pellegrino, F. A1 - Rades, Steffi A1 - Radnik, Jörg A1 - Hodoroaba, Vasile-Dan A1 - Spotto, G. A1 - Maurino, V. A1 - Martra, G. T1 - Beyond shape engineering of TiO2 nanoparticles: Post-synthesis treatment dependence of surface hydration, hydroxylation, Lewis acidity and photocatalytic activity of TiO2 anatase nanoparticles with dominant {001} or {101} facets N2 - TiO2 anatase nanoparticles are among the relevant players in the field of light-responsive semiconductor nanomaterials used to face environmental and energy issues. In particular, shape-engineered TiO2 anatase nanosheets with dominant {001} basal facets gained momentum because of the possibility to exploit different and/or improved functional behaviors with respect to usual bipyramidal TiO2 anatase nanoparticles, mainly exposing {101} facets. Nevertheless, such behavior depends in a significant extent on the physicochemical features of surfaces exposed by nanosheets. They can vary in dependence on the presence or removal degree of capping agents, namely, fluorides, used for shape-engineering, and experimental investigations in this respect are still a few. Here we report on the evolution of interfacial/ surface features of TiO2 anatase nanosheets with dominant {001} facets from pristine nanoparticles fluorinated both in the bulk and at their surface to nanoparticles with F− free surfaces by treatment in a basic solution and to totally F− free nanoparticles by calcination at 873 K. The nanoparticles fluorine content and its subsequent evolution is determined by complementary techniques (ion chromatography, TOF-SIMS, XPS, AES, SEM-EDX), probing different depths. In parallel, the evolution of the electronic properties and the Ti valence state is monitored by UV−vis spectroscopy and XPS. The calcination treatment results in {001} facets poorly hydroxylated, hydrated, and hydrophilic, which appear as surface features consequent to the expected (1 × 4) reconstruction. Moreover, IR spectroscopy of CO adsorbed as probe molecule indicates that the Lewis acidity of Ti4+ sites exposed on (1 × 4) reconstructed {001} facets of calcined TiO2 nanosheets is weaker than that of cationic centers on {101} facets of bipyramidal TiO2 anatase nanoparticles. The samples have also been tested in phenol photodegradation highlighting that differences in surface hydration, hydroxylation, and Lewis acidity between TiO2 nanoparticles with nanosheet (freed by F− by calcination at 873 K) and bipyramidal shape have a strong impact on the photocatalytic activity that is found to be quite limited for the nanoparticles mainly exposing (1 × 4) reconstructed {001} facets. KW - Nanoparticles KW - TiO2 KW - F- doping KW - Shape-controlled nanoparticles KW - Nanosheets PY - 2018 DO - https://doi.org/10.1021/acsanm.8b01477 SN - 2574-0970 VL - 1 IS - 9 SP - 5355 EP - 5365 PB - ACS Publications CY - Washington, DC, U.S.A. AN - OPUS4-46157 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rades, Steffi A1 - Oswald, F. A1 - Narbey, S. A1 - Radnik, Jörg A1 - Hodoroaba, Vasile-Dan T1 - Analytical approach for characterization of morphology and chemistry of a CH3NH3PbI3/TiO2 solar cell layered system N2 - Manufacturing of new perovskite layered solar cells with constant high light conversion Efficiency over time may be hampered by the loss of efficiency caused by structural and/or chemical alterations of the complex layered system. SEM/EDX combined with XPS were chosen as an appropriate methodical approach to characterize perovskite laboratory cells in depth and at surface, before and after light exposure. The layered perovskite system investigated here is based on glass covered with fluorine doped tin oxide, followed by thin films of TiO2, ZrO2, and a thick monolithic carbon. TiO2 film is subdivided into a dense layer covered by porous one constituted of nanoparticles of truncated bipyramidal shape. This layered system serves as the matrix for the perovskite. EDX spectral maps on cross sections of specimen have shown that Pb and I are distributed homogeneously throughout the porous layers C, ZrO2, and TiO2. SEM/EDX data show that 20 weeks of ambient daylight did not change significantly the in‐depth distribution of the elemental composition of Pb and I throughout the entire solar cell system. It was confirmed with EDX that nanoparticles identified in high‐resolution SEM micrographs contain mainly Pb and I, indicating these to be the perovskite crystals. However, a compositional and chemical altering began in the near‐surface region of the outermost ~10 nm after 2 months of illumination which was observed with XPS. T2 - ECASIA 2017 CY - Montpellier, France DA - 24.09.2017 KW - Solar Cell KW - SEM KW - EDX KW - XPS KW - layered system PY - 2018 DO - https://doi.org/10.1002/sia.6410 SN - 0142-2421 SN - 1096-9918 VL - 50 IS - 11 SP - 1234 EP - 1238 PB - John Wiley & Sons, Ltd. AN - OPUS4-46394 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Radnik, Jörg T1 - XPS at BAM - Some insights into our activities N2 - Some examples will be given showing the application of XPS in different fields, like polymers, nanoparticles, solar cells and inorganic thin films. T2 - Besuch beim GFZ Potsdam CY - Potsdam, Germany DA - 18.05.2018 KW - XPS KW - Surface analytics KW - Nanoparticles KW - Polymers KW - Solar cells PY - 2018 AN - OPUS4-44981 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Radnik, Jörg A1 - Müller, Anja T1 - Introduction to photoelectronspectroscopy N2 - A short introduction to XPS/ESCA with the focus on nanoparticles and the preparation of such particles for the measurements T2 - Meeting of ACE Nano CY - Berlin, Germany DA - 18.02.2019 KW - ESCA/XPS KW - Nanoparticles KW - Preparation PY - 2019 AN - OPUS4-47437 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Füllenbach, L.C. A1 - Perez, J. P. H. A1 - Freeman, H.M. A1 - Thomas, A.N. A1 - Mayanna, S. A1 - Parker, J. E. A1 - Göttlicher, J. A1 - Steininger, R. A1 - Radnik, Jörg A1 - Benning, L.G. A1 - Oelkers, E.H. T1 - Nanoanalytical Identification of Siderite Dissolution-Coupled Pb Removal Mechanisms from Oxic and Anoxic Aqueous Solutions N2 - Lead(II) is a toxic pollutant often found in metalcontaminated soils and wastewaters. In acidic aqueous environments, Pb(II) is highly mobile. Chemical treatment strategies of such systems therefore often include neutralization agents and metal sorbents. Since metal solubility and the retention potential of sorbents depend on the redox state of the aqueous system, we tested the efficiency of the naturally occurring redox-sensitive ferrous iron carbonate mineral siderite to remove Pb(II) from acidic aqueous solutions in batch experiments under oxic and anoxic conditions over a total of 1008 h. Siderite dissolution led to an increase in reactive solution pH from 3 to 5.3 and 6.9, while 90 and 100% of the initial aqueous Pb(II) (0.48 × 10−3 mol kg−1) were removed from the oxic and anoxic systems, respectively. Scanning and transmission electron microscopy, combined with X-ray absorption and photoelectron spectroscopy, indicated that under oxic conditions, Pb(II) was consumed by cerussite precipitation and inner-sphere surface complexation to secondary goethite. Under anoxic conditions, Pb(II) was removed by the rapid precipitation of cerussite. This efficient siderite dissolution-coupled sequestration of Pb(II) into more stable solid phases demonstrates this potential method for contaminated water Treatment regardless of the redox environment. KW - Siderite KW - X-ray absorption spectroscopy KW - X-ray photoelectron spectroscopy KW - Wastewater treatment PY - 2020 DO - https://doi.org/10.1021/acsearthspacechem.0c00180 VL - 4 IS - 11 SP - 1966 EP - 1977 PB - ACS Publication AN - OPUS4-51961 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kjaervik, Marit A1 - Dietrich, P. M. A1 - Thissen, A. A1 - Radnik, Jörg A1 - Nefedov, A. A1 - Natzeck, C. A1 - Wöll, C. A1 - Unger, Wolfgang T1 - Application of near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) in an in-situ analysis of the stability of the surface-supported metal-organic framework HKUST-1 in water, methanol and pyridine atmospheres N2 - Surface-supported metal-organic frameworks HKUST-1 (Hong Kong University of Science and Technology) were used as a model system for a development of a near ambient pressure (NAP) XPS based approach to investigate interaction with atmospheres of water, methanol or pyridine at pressures ranging from 1 to 4 mbar. The films were grown on a gold substrate functionalized with a COOH-terminated self-assembled monolayer using liquidphase epitaxy in a step-by-step fashion. Measurement protocols were developed and optimised for different gases in order to obtain spectra of similar quality in terms of signal intensity, noise and shape. Peak shapes were found to depend on the efficiency of charge compensation. Reference measurements in argon proved to be a useful strategy not only for the evaluation of the Cu(II)-fraction in pristine samples, but also to identify the contributions by the respective gas atmosphere to the C 1s and O 1s photoelectron spectra. Reduced copper was found during the exposition of HKUST-1 to water vapour and pyridine, but this effect was not observed in case of methanol. Additionally, it was established that there are no changes in relative Cu(II) percentage with increasing exposure time. This indicates that saturation was reached already at the lowest time of gas exposure. A detailed elucidation of the mechanism of Cu(II) reduction to Cu(I) in HKUST-1 mediated by water and pyridine is part of ongoing work and not in the scope of the present paper. KW - HKUST-1 KW - Near-ambient pressure X-ray photoelectron spectroscopy KW - Metal-organic frameworks KW - Interaction with atmospheres KW - Water PY - 2021 DO - https://doi.org/10.1016/j.elspec.2020.147042 SN - 0368-2048 IS - 247 SP - 147042 PB - Elsevier B.V. CY - Amsterdam, Netherlands AN - OPUS4-52098 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Perez, Jeffey Paulo H. A1 - Tobler, Dominique J. A1 - Thomas, Andrew N. A1 - Freeman, Helen M. A1 - Dideriksen, Knud A1 - Radnik, Jörg A1 - Benning, Liane G. T1 - Adsorption and reduction of arsenate during the Fe2+-induced transformation of ferrihydrite N2 - Iron (oxyhydr)oxides play an important role in controlling the mobility and toxicity of arsenic (As) in contaminated soils and groundwaters. However, dynamic subsurface geochemical conditions can potentially impact As sequestration since this is highly dependent on the dominant iron mineral phases present and the pathways through which they form. In this study, we investigated the Fe2+-induced transformation of As(V)-bearing ferrihydrite (As-FH) to more crystalline phases under relevant anoxic subsurface conditions. Specifically, we examined the influence of varying Fe2+(aq)/Fe(III)solid¬ ratios on the behavior and speciation of the mineral-bound As species during the mineralogical transformation of As-FH at pH 6.5 for 24 h. At lower Fe2+(aq)/Fe(III)solid¬ ratios (0.5 to 1), goethite, green rust sulfate (GR¬SO4) and lepidocrocite formed within the first 2 hours of the reaction, but only goethite and some unreacted FH remained after 24 h. At Fe2+(aq)/Fe(III)solid¬ ratio = 2, GRSO4 remained stable throughout the 24 h reaction, alongside goethite and unreacted FH. Despite >82% of the As-FH being transformed to goethite  GRSO4 in these reactions, no significant As release (>99.9% removal) was observed. However, while As remained mineral-bound, partial oxidation of the initially added As(V) was reduced to As(III), most likely, by the goethite-Fe2+(aq) redox couple. The extent of As(V) reduction increased from ~40% to ~50%, as the Fe2+(aq)/Fe(III)solid¬ ratio increased from 0.5 to 2. Overall, these results provide important insights into transformation pathways of iron (oxyhydr)oxide minerals in As contaminated, anoxic soils and sediments, and also demonstrate the great impact these can have on As oxidation state and, hence, toxicity and mobility in these environments. KW - Ferrihydrite KW - Mineral tranformation KW - XPS KW - Green rust KW - Goethite KW - XAS PY - 2019 DO - https://doi.org/10.1021/acsearthspacechem.9b00031 SN - 2472-3452 VL - 3 IS - 6 SP - 884 EP - 894 PB - ACS AN - OPUS4-48436 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Radnik, Jörg A1 - Kunz, Valentin A1 - Schneider, Markus A1 - Nymark, Penny A1 - Grafström, Roland A1 - Unger, Wolfgang T1 - Combining surface analytic and toxicity data for safer nanomaterials N2 - Nanomaterials are present in our everyday life. Paint coats, sunscreens, catalysts and additives for tyres are good examples for the use of such materials in mass-market products. The problem of the safety of nanomaterials is recognized as a problem for health and environment, which lead to the special registration of nanomaterials according to an annex of REACH as of 2020. But a great problem for the risk assessment of nanomaterials that several factors could influence the hazardous nature of them. Additional to composition, crystal structure, size and shape the surface properties of such particles belong to these parameters for risk assesment. The reason for the relevance of the surface is obvious: the smaller the particle, the higher is the share of the surface. Additionally, the surface is the region of the particle which interacts with the surrounding which is another crucial factor for the understanding the effect of a nanomaterial on health and environment. In the OECD Testing Programme on Manufactured Nanomaterials exists consequently an Endpoint 4.30 Surface Chemistry in Chapter 4. PHYSICAL AND CHEMICAL PROPERTIES. In summary, there is obviously a need for a correlation between surface chemical analytic data and toxicity. To fill in this gap, we present surface analytic results obtained with X-ray photoelectron spectroscopy and Time-of-Flight Secondary Ion Mass Spectrometry and correlate them with cytotoxic data gain by high-throughput screening experiments. It must be noted, that these experiments were done at the same set of titania materials taken from the JRC (Joint Research Centre of the European Union) Nanomaterials Repository. As material TiO2 was chosen due to its widespread use in consumer products, e.g. paint coats and sunscreens. With this new approach a better understanding of the influence of surface properties on the toxicity can be expected leading to a better risk assessment of these materials. T2 - ECASIA 2019 CY - Dresden, Germany DA - 15.09.2019 KW - Risk assessment KW - Nanomaterials KW - Surface analytic KW - Toxicology PY - 2019 AN - OPUS4-49090 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hahn, Marc Benjamin T1 - Behind the paper: Radiation, DNA and water: New techniques for deeper insights N2 - To gain deeper insights into the old questions about the influence of water on radiation interaction with DNA, new spectroscopic techniques had to be applied. KW - DNA KW - DNA radiation damage KW - XPS KW - Geant4 KW - Low energy electrons KW - OH radical KW - Hydrated DNA KW - Hydration shell KW - Double-strand break (DSB) KW - Dissociative electron attachment (DEA) KW - Single-strand break (SSB) KW - LEE KW - PES KW - Ionization KW - Reactive oxygen species KW - ROS KW - Base damage KW - Base loss KW - Cancer therapy KW - TOPAS KW - TOPAS-nbio PY - 2021 UR - https://go.nature.com/3gjZVWG SP - 1 EP - 3 PB - Springer Nature CY - London AN - OPUS4-52461 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Radnik, Jörg T1 - Elucidating core shell nanostructures with surface analytics N2 - XPS is a versatile tool for elucidating core shell structures. XPS can obtain information for organic compounds (polymer particle, organic coating ) which are hardly or not detectable with other Methods. XPS is an important tool for the risk assessement of nanoparticles T2 - Kratos German User Meeting CY - Online meeting DA - 26.05.2021 KW - Core-shell nanoparticles KW - X-ray photoelectron spectroscopy KW - Complementary methods PY - 2021 AN - OPUS4-52717 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -