Oxygen-Vacancy Dynamics and Entanglement with Polaron Hopping at the Reduced 
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Zhang, Dawei; Han, Zhongkang; Murgida, Gustavo E.; Ganduglia‐Pirovano, M. V.; Gao, Yi

doi:10.1103/physrevlett.122.096101

Cited by 61 publications

(67 citation statements)

References 46 publications

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“…A recent study of a CeO 2 ‐Rh inverse model catalyst concluded that oxygen spill‐over from the metal also plays an important role in regeneration [9] . Near‐surface oxygen vacancies are clearly important in oxygen exchange, with calculations indicating that subsurface oxygen vacancies are stabilized at the CeO 2 (111) surface [10–13] . Here we report the observation of a Ce=O terminated (111) surface of ceria.…”

Section: Figurementioning

confidence: 57%

Ce=O Terminated CeO₂

et al. 2021

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Section: Figurementioning

confidence: 57%

Ce=O Terminated CeO₂

et al. 2021

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“…As we can see, Ni species preferentially substitute the top‐layer cerium ions at the neighboring sites of V O , assisted and sustained by surficial polaron migration and oxygen diffusion. [ 14 ] There appears to be a thermodynamic trend to form defect clusters (Ni Ce + V O ) in the surface region, and their formation energy represented an important driving force for that aggregation to occur. Now the electron transfer became kinetically easier from the Ni 2+ dopant to the neighboring Ce 4+ through the V O defects.…”

Section: Resultsmentioning

confidence: 99%

Formation of FeOOH Nanosheets Induces Substitutional Doping of CeO₂₋_x with High‐Valence Ni for Efficient Water Oxidation

Wang

Long

et al. 2020

Advanced Energy Materials

130

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Electrochemical water splitting for hydrogen production, fuel cells, and metalair batteries are some of the promising approaches to tackle the environmental and energy problems. Central to these approaches involves oxygen evolution reaction (OER), which is a sluggish four-electron process. Finding a cost-effective OER catalyst with excellent activity and high stability will accelerate the wide spread employment of these techniques. [1] Owing to their low cost, nonprecious-metal-based electrocatalysts are in highly sought after for OER or other reactions. The first row transition metals such as Ni and Fe are promising candidates for designing OER electrocatalysts because their 3d electrons can be easily manipulated just like the precious metals, but their OER activity still needs to be improved. [2] Increasing the reaction active sites and optimizing the intrinsic activity of the catalysts are the two effective ways to improve their OER performance. Nanostructure engineering is widely used to enlarge the surface area in order to expose more active sites. Transition metal elements with high oxidation states are believed to have high intrinsic activity, especially for Ni. [3] Ni 2+ is the common ion in nickel salt used for the synthesis of Ni catalysts, and it is often difficult to oxidize Ni 2+ to Ni 3+ or even Ni 4+ and stabilize them under mild conditions. Instead, extreme conditions such as high pressure and oxidative environment are required. [3e] Ni in the ABO 3 perovskite structure with the high oxidation state of +3 was used for the synthesis of Ni-based catalysts, but the precursor is also the Ni 2+ salt, and the synthesis process involves multiple steps including adding organic additives and using high temperature. [3a,c] Therefore, there is a need to develop simpler and cost-effective methods for the preparation of high-valence Ni for electrocatalytic applications. Ceria (CeO 2) is a nonstoichiometric material. The facile shift between Ce 4+ and Ce 3+ should promote the electron transfer between CeO 2 and other components in Ce-containing hybrid catalysts, if they are made for this purpose. [4] In our previous work, [5] we showed that when CeO 2 is reduced to CeO 2−x , electron transfer is further enhanced. Herein, by using Transition metal elements such as Ni in high oxidation states can promote oxygen evolution reaction (OER) activity, but it is difficult to prepare dispersed Ni 3+ or even Ni 4+ species under mild conditions. Herein, a onestep synthesis of high-valence nickel-doped CeO 2−x covered with FeOOH nanosheets in the presence of Ni 2+ /Fe 3+ is reported. A series of ex situ and in situ experiments reveal the etching effect on ceria of the H + species from the hydrolysis of Fe 3+ , which induces substitutional doping of Ni 2+ ions into the etched sites and their further oxidation to the high-valance Ni 3+ /Ni 4+ by coupling to the Ce 4+ /Ce 3+ pair in the oxygen-vacancy-rich CeO 2−x. Concomitantly, Fe 3+ is deposited on the surface of ceria as FeOOH nanosheets. The dispersed high-valent Ni 3+ /N...

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“…The global analysis shows that the initial component (black curve in Figure 4b) rises in less than 70 fs (IRF Normalized Weight of polarons affects oxygen vacancy formation and mobility 33 , as well as the interaction with adsorbates 34 . Understanding the dynamics of trapping and recombination of photogenerated electron-hole pairs is relevant and challenging.…”

Section: Have Demonstrated That Localization Onmentioning

confidence: 99%

Ultrafast Formation of Small Polarons and the Optical Gap in CeO₂

Cresi

Mario

Catone

et al. 2020

J. Phys. Chem. Lett.

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The ultrafast dynamics of excited states in cerium oxide are investigated to access the early moments of polaron formation, which can influence the photocatalytic functionality of the material. UV transient absorbance spectra of photoexcited CeO 2 exhibit a bleaching of the band edge absorbance induced by the pump and a photoinduced absorbance feature assigned to Ce 4f → Ce 5d transitions. A blue shift of the spectral response of the photoinduced absorbance signal in the first picosecond after the pump excitation is attributed to the dynamical formation of small polarons with a characteristic time of 330 fs. A further important result of our work is that the combined use of steady-state and ultrafast transient absorption allows us to propose a revised value for the optical gap for ceria ( E og = 4 eV), significantly larger than usually reported.

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Oxygen-Vacancy Dynamics and Entanglement with Polaron Hopping at the Reduced CeO2(111) Surface

Cited by 61 publications

References 46 publications

Ce=O Terminated CeO₂

Ce=O Terminated CeO₂

Formation of FeOOH Nanosheets Induces Substitutional Doping of CeO₂₋_x with High‐Valence Ni for Efficient Water Oxidation

Ultrafast Formation of Small Polarons and the Optical Gap in CeO₂

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Oxygen-Vacancy Dynamics and Entanglement with Polaron Hopping at the Reduced CeO2(111) Surface

Cited by 61 publications

References 46 publications

Ce=O Terminated CeO2

Ce=O Terminated CeO2

Formation of FeOOH Nanosheets Induces Substitutional Doping of CeO2−x with High‐Valence Ni for Efficient Water Oxidation

Ultrafast Formation of Small Polarons and the Optical Gap in CeO2

Contact Info

Product

Resources

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Ce=O Terminated CeO₂

Ce=O Terminated CeO₂

Formation of FeOOH Nanosheets Induces Substitutional Doping of CeO₂₋_x with High‐Valence Ni for Efficient Water Oxidation

Ultrafast Formation of Small Polarons and the Optical Gap in CeO₂