Electron Mobility via Polaron Hopping in Bulk Ceria: A First-Principles Study

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• 作者：Jos茅 J. Plata ; Antonio M. M谩rquez ; Javier Fdez. Sanz
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：July 18, 2013
• 年：2013
• 卷：117
• 期：28
• 页码：14502-14509
• 全文大小：375K
• 年卷期：v.117,no.28(July 18, 2013)
• ISSN：1932-7455

文摘

The outstanding catalytic properties of cerium oxides and, consequently, the broad use in heterogeneous catalysis rely on the easy Ce³⁺ 鈫?Ce⁴⁺ redox conversion. Within the two-state model of Marcus, the electron transfer associated with the redox process is governed by the electronic coupling matrix element V_AB that accounts for the interaction between the diabatic electronic states at the crossing seam. Here we present a computational analysis based on ab initio quantum mechanics theory that allows for a characterization of negative polaron structures and intrinsic polaron hopping in bulk CeO₂. The relevant parameters inherent to the model: reorganization energy, activation barrier, and electronic coupling for the 4f鈫?4f electron hopping are estimated for several models. Our analysis predicts an activation barrier of 0.4 eV and a transmission coefficient 魏 = 0.81, confirming the earlier proposed adiabatic theory of small polaron and hopping conductivity in reduced bulk ceria.