title: Investigation of reactions between trace gases and functional CuO nanospheres and octahedrons using NEXAFS-TXM imaging.
abstract: In order to take full advantage of novel functional materials in the next generation of sensorial devices scalable processes for their fabrication and utilization are of great importance. Also understanding the processes lending the properties to those materials is essential. Among the most sought-after sensor applications are low-cost, highly sensitive and selective metal oxide based gas sensors. Yet, the surface reactions responsible for provoking a change in the electrical behavior of gas sensitive layers are insufficiently comprehended. Here, we have used near-edge x-ray absorption fine structure spectroscopy in combination with x-ray microscopy (NEXAFS-TXM) for ex-situ measurements, in order to reveal the hydrogen sulfide induced processes at the surface of copper oxide nanoparticles, which are ultimately responsible for triggering a percolation phase transition. For the first time these measurements allow the imaging of trace gas induced reactions and the effect they have on the chemical composition of the metal oxide surface and bulk. This makes the new technique suitable for elucidating adsorption processes in-situ and under real operating conditions.
authors.affiliation: Institute for Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Henzler
authors.affiliation: Institut für Makromolekulare Chemie, University of Freiburg, 79104 Freiburg, Germany.|Institut für Physikalische Chemie, University of Freiburg, 79104 Freiburg, Germany.|Laboratory for Gas Sensors, Department of Microsystems Engineering, University of Freiburg, Georges-Köhler Allee 102, 79110 Freiburg.
authors.forename: Axel
authors.initials: A
authors.lastname: Heilemann
authors.affiliation: Laboratory for Gas Sensors, Department of Microsystems Engineering, University of Freiburg, Georges-Köhler Allee 102, 79110 Freiburg.
authors.forename: Janosch
authors.initials: J
authors.lastname: Kneer
authors.affiliation: Institute for Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Guttmann
authors.affiliation: Institute for Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
authors.forename: He
authors.initials: H
authors.lastname: Jia
authors.affiliation: Institut für Makromolekulare Chemie, University of Freiburg, 79104 Freiburg, Germany.|Institut für Physikalische Chemie, University of Freiburg, 79104 Freiburg, Germany.
authors.forename: Eckhard
authors.initials: E
authors.lastname: Bartsch
authors.affiliation: Institute for Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
authors.forename: Yan
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Laboratory for Gas Sensors, Department of Microsystems Engineering, University of Freiburg, Georges-Köhler Allee 102, 79110 Freiburg.
authors.forename: Stefan
authors.initials: S
authors.lastname: Palzer