Direct Observation of the Electroadsorptive Effect on Ultrathin Films for Microsensor and Catalytic-Surface Control

Authors

  • Prof. Dr. Theodor Doll,

    Corresponding author
    1. Microstructure Physics, University of Mainz, Staudinger Weg 7, 55128 Mainz (Germany)
    2. Current address: Biomedical Engineering, VIANNA, Hannover Medical School, Feodor-Lynen-Str. 35, 30625 Hannover (Germany)
    • Current address: Biomedical Engineering, VIANNA, Hannover Medical School, Feodor-Lynen-Str. 35, 30625 Hannover (Germany)
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  • Dr. Juan J. Velasco-Velez ,

    1. Microstructure Physics, University of Mainz, Staudinger Weg 7, 55128 Mainz (Germany)
    2. Materials Science Division, Lawrence Berkeley National Laboratory, Cyclotron Road, Berkeley CA 94720 (USA)
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  • Dr. Dirk Rosenthal,

    Corresponding author
    1. Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4–6, 14195 Berlin (Germany)
    • Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4–6, 14195 Berlin (Germany)
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  • Dr. Jonathan Avila ,

    1. Laboratorio de Filmes Finos e Superficies (LFFS), CFM, Universidade Federal de Santa Catarina, Caixa Postal 476, CEP 88040-900 Florianópolis, SC (Brasil)
    2. Departamento de Física, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile)
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  • Prof. Dr. Victor Fuenzalida

    1. Departamento de Física, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile)
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Abstract

Microchemical sensors and catalytic reactors make use of gases during adsorption in specific ways on selected materials. Fine-tuning is normally achieved by morphological control and material doping. The latter relates surface properties to the electronic structure of the bulk, and this suggests the possibility of electronic control. Although unusual for catalytic surfaces, such phenomena are sometimes reported for microsensors, but with little understanding of the underlying mechanisms. Herein, direct observation of the electroadsorptive effect by a combination of X-ray photoelectron spectroscopy and conductivity analysis on nanometre-thick semiconductor films on buried control electrodes is reported. For the SnO2/NO2 model system, NO3 surface species, which normally decay at the latest within minutes, can be kept stable for 1.5 h with a high coverage of 15 % under appropriate electric fields. This includes uncharged states, too, and implies that nanoelectronic structures provide control over the predominant adsorbate conformation on exterior surfaces and thus opens the field for chemically reactive interfaces with in situ tunability.

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