Dresden 2011 – scientific programme
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O: Fachverband Oberflächenphysik
O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)
O 60.124: Poster
Wednesday, March 16, 2011, 17:30–21:00, P4
Reduction of Thin NiO Films by Carbon Monoxide — •Oliver Höfert1, Wei Zhao1, Karin Gotterbarm1, Andreas Bayer1, Junfa Zhu2, Christian Papp1, and Hans-Peter Steinrück1 — 1Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen — 2National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, People’s Republic of China
NiO is an important material in heterogeneous photocatalysis for degradation of azodyes [1] or water splitting [2]. We studied the reactivity of different thin NiO films on Pd(100) towards CO by in situ XPS applying synchrotron radiation at BESSY II. Our data shows that closed and well ordered NiO films with less than 2 ML are indeed reduced to metallic Ni by exposure to CO above 400 K. The reduction of NiO by CO is chemically reversible as was shown by subsequent reoxidation of the metallic Ni by O2. The influence of Pd to the reaction could be excluded. Our kinetic investigations revealed a coupling of diffusion and reaction in the reduction process. For both mechanisms we determined the activation energy. Additionally, the reoxidized films showed a different behaviour and could not be fully reduced due to structural changes.
This work was supported by BMBF (05 ES3XBA/5) and the DFG through the Cluster of Excellence "Engineering of Advanced Materials".
[1] Hu, X. et al (2010), J. Chem. Tec. & Biotec., 85(11)
[2] Kato, H. et al (2001),J. Phys. Chem. B, 105 (19)