TY - CONF A1 - Sachse, René A1 - Pflüger, Mika A1 - Velasco-Vélez, Juan-Jesús A1 - Sahre, Mario A1 - Radnik, Jörg A1 - Bernicke, Michael A1 - Bernsmeier, Denis A1 - Hodoroaba, Vasile-Dan A1 - Krumrey, Michael A1 - Strasser, Peter A1 - Hertwig, Andreas A1 - Kraehnert, Ralph T1 - Operando electrochemical spectroscopic ellipsometry: Material properties of highly active mesoporous IrO IrOxfilms revealed under realistic OER conditions N2 - Rising energy demand and the impending climate change require the development of a sustainable, fossil-free fuel and chemical production on a global scale. Hydrogen production via water electrolysis will be a fundamental cornerstone in this endeavor. The activity and stability of respective electrode coatings strongly depends on the coating's properties, i.e. phase composition, crystallinity, electrical conductivity, accessible surface, wettability and many other factors. The key to the development of improved catalysts is a better understanding of the relations between their performance, stability and physicochemical properties. However, those relations can be complex, and are strongly influenced also by the reaction environment. Hence, operando analysis of the catalyst material during catalysis at realistic potentials and current densities is highly desirable. Yet, many analytical techniques cannot be applied in liquid environments at realistic potentials and current densities. We propose environmental ellipsometric analysis in a dedicated electrochemical flow cell as a new method to evaluate gas evolution reactions operando under realistic working conditions. Figure 1 illustrates schematically the developed technique. Key factors to success are highly active model-type catalysts with template-controlled porosity, a suitable sample environment, a deep understanding of the spectroscopic method and respective model development, as well as concise cross validation with numerous other analytical techniques. The method was developed and validated by analyzing a calcination series (300 - 600°C) of mesoporous templated IrOx films ex-situ and operando under oxygen evolution reaction (OER) conditions. The employed environmental electrochemical spectroscopic ellipsometric analysis (ECSE) revealed during OER the change of optical and electronic properties, i.e. the dielectric functions (real ε1 and imaginary part ε2), electrical and electronic properties such as resistivity (ρ) and band-to-band transitions (p-d band transitions). Film thickness and porosity were validated by means of scanning electron microscopy (SEM), X-ray reflectometry (XRR) or ellipsometric porosimetry (EP), electrical and electronic properties by means of conductivity measurements, X-ray photoelectron spectroscopy (XPS) or UV-Vis-NIR absorption spectroscopy. The electronic structures of the catalysts from valence electron energy loss spectra (VEELS) derived from the real (ε1) and imaginary part (ε2) of the dielectric function from SE measurements reveal a direct correlation with electrochemical activities in OER. In the presentation reversible and irreversible potential-dependent changes of the catalyst properties during operation will be discussed along with the dynamics of gas formation, transport and dissolution at different potentials. T2 - 54. Jahrestreffen deutscher Katalytiker CY - Online meeting DA - 16.03.2021 KW - Spectroscopic ellipsometry KW - Electrocatalysis KW - Oxygen evolution reaction KW - Mesoporous iridium oxide films KW - Non-destructive operando analysis PY - 2021 AN - OPUS4-52928 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sachse, René A1 - Pflüger, Mika A1 - Velasco Vélez, Juan Jesús A1 - Sahre, Mario A1 - Radnik, Jörg A1 - Bernicke, Michael A1 - Bernsmeier, Denis A1 - Hodoroaba, Vasile-Dan A1 - Krumrey, Michael A1 - Strasser, Peter A1 - Kraehnert, Ralph A1 - Hertwig, Andreas T1 - Operando electrochemical spectroscopic ellipsometry: Material properties of highly active mesoporous IrO IrOxfilms revealed under realistic OER conditions N2 - In the face of rising energy demand and the impending climate change the development of a sustainable, fossil-free fuel and chemical production is of global importance. One possible goal is the development of electrochemical conversion processes using catalysts. Porous materials play an important role in such energy applications. The activity and stability of each catalyst is highly dependent on the properties of the coating, i.e., phase composition, crystallinity, accessible surface area, and many other factors. The key to the development of improved catalysts is a better understanding of the relations between their performance, stability and physico-chemical properties. However, the complex morphology of such catalysts constitutes a challenge even for modern analytical techniques. Spectroscopic ellipsometry (SE) is a versatile method for studying material properties by using appropriate models (e.g., film thickness, optical and electronic properties). Ellipsometric models need to be validated in order to produce accurate results. In a first step, the model for the ellipsometric fit studies of a calcination series of mesoporous iridium oxide films (300 – 600 °C) was investigated and validated with respect to their material properties.[4] The information on electronic structure of the catalysts shows a direct correlation with electrochemical activities. The development of an environmental electrochemical cell offers the possibility of investigations under operando conditions. Thus, changes in optical and electronic properties can be induced and monitored during the electrocatalytic oxygen evolution reaction. T2 - 9th International Conference on Spectroscopic Ellipsometry CY - Beijing, China DA - 22.05.2022 KW - Mesoporous iridium oxide films KW - Non-destructive operando analysis KW - Oxygen evolution reaction KW - Spectroscopic ellipsometry PY - 2022 AN - OPUS4-54915 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sachse, René A1 - Pflüger, Mika A1 - Velasco-Vélez, Juan-Jesús A1 - Sahre, Mario A1 - Radnik, Jörg A1 - Bernicke, Michael A1 - Bernsmeier, Denis A1 - Hodoroaba, Vasile-Dan A1 - Krumrey, Michael A1 - Strasser, Peter A1 - Hertwig, Andreas A1 - Kraehnert, Ralph T1 - Operando electrochemical spectroscopic ellipsometry: Material properties of highly active mesoporous IrO IrOxfilms revealed under realistic OER conditions N2 - Rising energy demand and the impending climate change require the development of a sustainable, fossil-free fuel and chemical production on a global scale. Hydrogen production via water electrolysis will be a fundamental cornerstone in this endeavor. The activity and stability of respective electrode coatings strongly depends on the coating's properties, i.e. phase composition, crystallinity, electrical conductivity, accessible surface, wettability and many other factors. The key to the development of improved catalysts is a better understanding of the relations between their performance, stability and physicochemical properties. However, those relations can be complex, and are strongly influenced also by the reaction environment. Hence, operando analysis of the catalyst material during catalysis at realistic potentials and current densities is highly desirable. Yet, many analytical techniques cannot be applied in liquid environments at realistic potentials and current densities. We propose environmental ellipsometric analysis in a dedicated electrochemical flow cell as a new method to evaluate gas evolution reactions operando under realistic working conditions. Figure 1 illustrates schematically the developed technique. Key factors to success are highly active model-type catalysts with template-controlled porosity, a suitable sample environment, a deep understanding of the spectroscopic method and respective model development, as well as concise cross validation with numerous other analytical techniques. The method was developed and validated by analyzing a calcination series (300 - 600°C) of mesoporous templated IrOx films ex-situ and operando under oxygen evolution reaction (OER) conditions. The employed environmental electrochemical spectroscopic ellipsometric analysis (ECSE) revealed during OER the change of optical and electronic properties, i.e. the dielectric functions (real ε1 and imaginary part ε2), electrical and electronic properties such as resistivity (ρ) and band-to-band transitions (p-d band transitions). Film thickness and porosity were validated by means of scanning electron microscopy (SEM), X-ray reflectometry (XRR) or ellipsometric porosimetry (EP), electrical and electronic properties by means of conductivity measurements, X-ray photoelectron spectroscopy (XPS) or UV-Vis-NIR absorption spectroscopy. The electronic structures of the catalysts from valence electron energy loss spectra (VEELS) derived from the real (ε1) and imaginary part (ε2) of the dielectric function from SE measurements reveal a direct correlation with electrochemical activities in OER. In the presentation reversible and irreversible potential-dependent changes of the catalyst properties during operation will be discussed along with the dynamics of gas formation, transport and dissolution T2 - E MRS 2021 SPRING MEETING CY - Online meeting DA - 31.05.2021 KW - Spectroscopic ellipsometry KW - Ectrocatalysis KW - Oxygen evolution reaction KW - Mesoporous iridium oxide films KW - Non-destructive operando analysis PY - 2021 AN - OPUS4-52929 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sachse, René A1 - Pflüger, Mika A1 - Velasco-Vélez, Juan-Jesús A1 - Sahre, Mario A1 - Radnik, Jörg A1 - Bernicke, Michael A1 - Bernsmeier, Denis A1 - Hodoroaba, Vasile-Dan A1 - Krumrey, Michael A1 - Strasser, Peter A1 - Kraehnert, Ralph A1 - Hertwig, Andreas T1 - Operando electrochemical spectroscopic ellipsometry: Material properties of highly active mesoporous IrOx films revealed under realistic OER conditions N2 - Hydrogen production via water electrolysis will be an essential cornerstone in development of sustainable, fossil-free fuel and chemical production on a global scale. The activity and stability of each catalyst is highly dependent on the properties of the coating, i.e., phase composition, crystallinity, accessible surface area, and many other factors. The key to developing improved catalysts is a better understanding of the relationships between their performance, stability, and physicochemical properties. However, these relationships can be complex and are also strongly influenced by the reaction environment. Therefore, operando analysis of the catalyst material during catalysis at realistic potentials and current densities is highly desirable. However, many analytical techniques cannot be applied in liquid environments at realistic potentials and current densities. We propose environmental ellipsometric analysis in a dedicated electrochemical flow cell as a method to evaluate gas evolution reactions operando under realistic working conditions. Figure 1 illustrates schematically the developed technique. Key factors to success are highly active model-type catalysts, a suitable sample environment, and a deep understanding of the appropriate model development, as well as concise cross validation with numerous other analytical techniques. The method was developed and validated by analyzing a calcination series (300 – 600 °C) of mesoporous templated IrOx films ex-situ and operando under oxygen evolution reaction (OER) conditions. The employed environmental electrochemical spectroscopic ellipsometric (ECSE) analysis revealed during OER the change of optical and electronic properties, i.e. the dielectric functions, resistivity and band-to-band transitions (p-d band transitions). Film thickness and porosity were validated by means of scanning electron microscopy (SEM), X-ray reflectometry (XRR) or ellipsometric porosimetry (EP), electrical and electronic properties by means of conductivity measurements, X-ray photoelectron spectroscopy (XPS) or UV-Vis-NIR absorption spectroscopy. The electronic structures of the catalysts from valence electron energy loss spectra (VEELS) derived from ε1 and ε2 from SE measurements reveal a direct correlation with electrochemical activities in OER. In the presentation reversible and irreversible potential-dependent changes of the catalyst properties during operation will be discussed along with the dynamics of gas formation, transport and dissolution at different potentials. T2 - 11th Workshop Ellipsometry (WSE 11) CY - Steyr, Austria DA - 06.09.2021 KW - Ectrocatalysis KW - Mesoporous iridium oxide films KW - Non-destructive operando analysis KW - Oxygen evolution reaction KW - Spectroscopic ellipsometry PY - 2021 AN - OPUS4-53915 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sachse, René A1 - Kotil, L. A1 - Hodoroaba, Vasile-Dan A1 - Bernsmeier, Denis A1 - Kraehnert, R. A1 - Hertwig, Andreas T1 - Spectroscopic ellipsometric analysis of elemental composition and porosity of mesoporous iridium-titanium mixed oxide thin films for electrocatalytic splitting of water N2 - Porous materials play an important role in several fields of technology, especially for energy applications like photovoltaics, electrolysis or batteries. The activity of porous films is affected by properties like porosity, film thickness, chemical composition of the material as well as the crystallinity of the framework. The complex morphology of such porous films constitutes a challenge for modern analytical techniques and requires approaches employing the combination/complementation of data of different analytical methods. In this contribution we characterize thin mesoporous iridium-titanium mixed oxide film properties by spectroscopic ellipsometry (SE). Mesoporous iridium oxide - titanium oxide (IrOx-TiOx) films were prepared via dip-coating of a solution containing a triblock-copolymer as structure-directing agent, an iridium precursor as well as a titanium precursor in ethanol. Deposited films with different amounts of iridium (0 wt%Ir to 100 wt%Ir) were synthesized and calcined in air. The thin films were analyzed with SE using the Bruggeman effective medium approximation (BEMA) for modelling. The results were compared with electron probe microanalysis (EPMA) as part of a combined SEM/EDS/STRATAGem Analysis. T2 - 8th International conference on spectroscopic ellipsometry (ICSE-8) CY - Barcelona, Spain DA - 26.05.2019 KW - Mesoporous iridium-titanium mixed oxides KW - Thin films KW - Spectroscopic ellipsometry KW - Oxygen evolution reaction KW - EPMA KW - Ellipsometric porosimetry PY - 2019 AN - OPUS4-48387 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sachse, René A1 - Bernsmeier, Denis A1 - Hertwig, Andreas A1 - Hodoroaba, Vasile-Dan A1 - Kraehnert, Ralph T1 - Spectroscopic ellipsometry for the determination of thickness and porosity of mesoporous metal oxide films N2 - Thin mesoporous metal oxide films are versatile and attractive candidates for several energy applications like photovoltaics, electrolysis or batteries. Due to their high surface area and ordered pore structure, mesoporous metal oxides demonstrate higher activities. The performance of the porous films is affected by properties like size and shape of the mesopores as well as the crystallinity of the framework. The exact determination and metrological evaluation of the complex morphology of thin mesoporous films requires a new analytical approach employing to combined data of different analytical methods. In this contribution we present a novel evaluation procedure for spectroscopic ellipsometry (SE) to analyse thin mesoporous iridium oxide films. Mesoporous iridium oxide films were prepared via dip-coating of a solution containing a triblock-copolymer as structure directing agent and an iridium precursor in ethanol. Deposited films were calcined in air at temperatures between 300 and 600 °C. Their morphology was studied with SEM and an electron probe microanalysis (EPMA) and correlated via SE with a Bruggeman effective medium approximation (BEMA). The developed SE model described the film thickness as well as the porosity. ... The contribution will assess in detail the novel approach to analyse the morphology and porosity of thin metal oxide films with spectroscopic ellipsometry. Moreover, the advantages of the new developed approach will be discussed as well as combination of datasets from multiple measurements to development new methods for innovative energy technologies. T2 - 30. Deutsche Zeolith-Tagung gemeinsam mit dem Jahrestreffen der ProcessNet-Fachgruppe Adsorption CY - Christian-Albrechts-Universität zu Kiel, Germany DA - 28.02.2018 KW - Mesoporous materials KW - Iridium oxide films KW - Electro catalyst KW - Spectroscopic ellipsometry KW - Thin film metrology KW - Multi-sample analysis PY - 2018 AN - OPUS4-45134 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sachse, René A1 - Hertwig, Andreas A1 - Hodoroaba, Vasile-Dan A1 - Kraehnert, R. T1 - Spectroscopic ellipsometry for the determination of thickness and porosity of mesoporous metal oxide films N2 - Thin mesoporous metal oxide films are versatile and attractive candidates for several energy applications like photovoltaics, electrolysis or batteries. Due to their high surface area and ordered pore structure, mesoporous metal oxides demonstrate higher activities. The performance of the porous films is affected by properties like size and shape of the mesopores as well as the crystallinity of the framework. The exact determination and metrological evaluation of the complex morphology of thin mesoporous films requires a new analytical approach employing to combined data of different analytical methods. In this contribution we present a novel evaluation procedure for spectroscopic ellipsometry (SE) to analyse thin mesoporous iridium oxide films. Mesoporous iridium oxide films were prepared via dip-coating of a solution containing a triblock-copolymer as structure directing agent and an Iridium precursor in ethanol. Deposited films were calcined in air at temperatures between 300 and 600 °C. Their morphology was studied with SEM and an electron probe microanalysis (EPMA) and correlated via SE with a Bruggeman effective medium approximation (BEMA). The developed SE model described the film thickness as well as the porosity. ... The contribution will assess in detail the novel approach to analyse the morphology and porosity of thin metal oxide films with spectroscopic ellipsometry. Moreover, the advantages of the new developed approach will be discussed as well as combination of datasets from multiple measurements to development new methods for innovative energy technologies. T2 - 10th Workshop Ellipsometry 2018 CY - Chemnitz University of Technology, Germany DA - 19.03.2018 KW - Mesoporous materials KW - Iridium oxide films KW - Electro catalyst KW - Spectroscopic ellipsometry KW - Thin film metrology KW - Multi-sample analysis PY - 2018 AN - OPUS4-45143 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Beck, Uwe A1 - Griepentrog, Michael A1 - Hertwig, Andreas A1 - Weise, Matthias T1 - White light interference microscopy, ellipsometry, and instrumented indentation testing as reference procedures N2 - The paper addresses “WHITE LIGHT INTERFERENCE MICROSCOPY, ELLIPSOMETRY, AND INSTRUMENTED INDENTATION TESTING AS REFERENCE PROCEDURES“ and is subdivided in the following sections: 1. Measurement vs. testing vs. reference procedures, 2. White light interference microscopy (WLIM) for determination of step height h, 3. Spectroscopic ellipsometry (SE) for determination of layer thickness d and 4. Instrumented indentation testing (IIT) for determination of indentation hardness HIT. The following points are discussed in more detail: methodology of measurement and testing, uncertainty budgets for direct (WLIM), model-based (SE) and formula-based (IIT) reference procedures by means of specific examples. It is shown that standardization efforts are connected to reference procedures. T2 - Referenzverfahren CY - BAM, Berlin, Germany DA - 21.02.2018 KW - Reference procedures KW - Uncertainty budgets KW - White light interference microscopy KW - Spectroscopic ellipsometry KW - Instrumented indentation testing PY - 2018 AN - OPUS4-44256 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -