Charge Transport over the Defective CeO₂(111) Surface

Abstract

First-principles calculations have been performed to explore the charge transport process over defective CeO2(111). Charge transport can proceed either by direct migration of the oxygen anion (i.e., vacancy diffusion) or by a polaron-hopping-assisted mechanism. On the basis of DFT+U calculations, we found that the latter process is significantly more favorable than the former. The overall barrier for charge transport involving polaron migration, followed by oxygen diffusion, is determined by the barrier for polaron hopping, which amounts to 0.18 eV. This computed value is in good agreement with the experimental barrier for ceria with a low defect density. We have shown by a careful analysis of the magnetization density, the density of states, and the reaction pathway trajectory that this process is phonon induced. Our results provide valuable insights into carrier drift processes over defective metal oxide surfaces.

Machine learning for heterogeneous catalyst design and discovery

“…Dynamics in catalysis are so ubiquitous that catalysts have been referred to as “living” systems. For example, the distribution and concentration of vacancy sites in catalyst supports can change under reaction conditions and impact catalytic performance . Ostwald ripening (the growth of larger nanoparticles from smaller nanoparticles), or nanoparticle disintegration into single atoms are also common dynamic phenomena that can change nanoparticle activity and selectivity .…”

Highly stable and Active Cu1/CeO2 Single‐Atom Catalyst for CO Oxidation: A DFT Study

“…[22] And U = 4.5 eV is extnsively used in the simulation of CeO 2 system. [4,[30][31][32][33] For the calculations of Cu 1 /CeO 2 (111), we used a periodic slab with a (4 4) supercell in which one of the surface Ce atoms was substituted by one TM atom. The CeO 2 (111) slab model is two CeÀOÀCe layers thick and the vacuum gap was set to 15 Å .…”

“…The following CO 2 desorption costs energy of 0.55 eV (IM2→IM3). Notably, the formation energy of oxygen vacancy at the Cu + center of Cu 1 /CeO 2 (111) is 2.58 eV with respect to gaseous O 2 , a little higher than that of free CeO 2 (111) surface . Liu et al.…”

“…The chocie of U value has a negligible influence on the thermodynamic or kinetic energy property of CeO 2 system . And U =4.5 eV is extnsively used in the simulation of CeO 2 system ,. For the calculations of Cu 1 /CeO 2 (111), we used a periodic slab with a (4×4) supercell in which one of the surface Ce atoms was substituted by one TM atom.…”

“…CeO 2 (111) is the most thermodynamically stable termination of CeO 2 , [29] and generally used to mimic the surface of CeO 2 . [4,5,[30][31][32][33][34][35][36][37][38][39] In this work, we employ DFT simulations to examine the stability of Cu single atoms on CeO 2 (111) and its reactivity for CO oxidation. We propose that Cu atom on CeO 2 (111) is enough stable and active for CO oxidation and thus a promising single-atom catalyst.…”