Time-Domain View of Polaron Dynamics in Metal Oxide Photocatalysts

Unveiling the Structure of Oxygen Vacancies in Bulk Ceria and the Physical Mechanisms behind Their Formation

“…Upon removal of an oxygen atom from CeO 2 , two extra electrons remain and are localized on Ce 4+ ions, leading to the formation of Ce 3+ . ,, This process prompts lattice relaxation and introduces strain, which is attributed to the formation of O V . It should be noted that photoexcitation, dopants, and hydrogen atom adsorption can also introduce excess electrons, which may lead to polaron formation and lattice relaxation. − Density of states analyses have revealed that these O V ’s induce an intermediate state between the O 2 p and Ce 4 f orbitals, stemming from the occupied Ce 4 f orbitals . Prior studies highlight that the excess electrons preferentially localize on second-nearest neighbor (2N) outer cations around the O V on the CeO 2 (111) surface. ,− Utilizing the DFT+U methodology to investigate various O V concentrations within defective bulk ceria, Murgida and colleagues observed that, similarly, excess electrons tend to localize around 2N outer cations adjacent to the O V .…”