Mechanism of CO and O₃ sensing on WO₃ surfaces: First principle study
2011
Oison, Vincent | Saadi, Lama | Lambert-Mauriat, Caroline | Hayn, Roland
The microscopic mechanism of O₃ and CO sensing on WO₃ surfaces is clarified by a first principle study. It is shown that ozone reduces to O₂ on the (001) surface of WO₃ decreasing in such a way the number of oxygen vacancies and the conductivity (since oxygen vacancies act as donors in WO₃). The mechanism of CO sensing is just the opposite: the CO molecule is oxidized to CO₂ on the WO₃ surface increasing the number of oxygen vacancies and the conductivity. The reaction enthalpy for the reduction process of O₃ is found to be −2.54eV in local density approximation (LDA) and −2.86 in generalized gradient approximation (GGA). The corresponding values for CO are −1.73eV (LDA) and −1.52eV (GGA). The adsorptions of O₃ and CO without reduction or oxidation are also calculated but the related energies are much smaller.
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