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Atomic vacancies in oxides induce deviations from ideal stoichiometry, critically influencing their functional properties in applications such as energy storage-conversion, catalysis, and electronic devices. The dynamic behavior of these vacancies as main mass transport mediums to exchange chemical species with surroundings under operating conditions is central to oxide redox reactions running with the Mars-van Krevelen (MvK) mechanism; yet in-situ atomic-scale monitoring of the vacancy dynamics and vacancy-induced secondary defects within oxides remains challenging due to both their rapid transport kinetics at buried subsurface/interface and characterization difficulties, arising from the insulating nature of bulk oxides and the spatial-resolution requirement in reaction conditions. These challenges hinder precise defect engineering for the performance optimization of functional oxides. In this review, recent advancements in tracking oxygen vacancy and vacancy-induced secondary defects dynamics in oxides, including surface steps, cation vacancies, interfacial dislocations, ledges, and interfaces, have been summarized. The dynamic interconversion of defects and their synergistic effects on surface/subsurface/interface evolution are mainly discussed. The aim of this review is to enhance understanding of defect dynamics and their pivotal role in modulating structural dynamics and surface reaction reactivity, which is highly relevant to the catalyst activity/selectivity/stability evaluation of functional oxide catalysts for electroreduction and catalytic oxidation reactions. Finally, strategies to control buried subsurface and interfacial defects (interface engineering) through tailored surface reactions are proposed, offering new pathways to customize the performance of advanced oxide-based materials.
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Two decades of ceria nanoparticles research: structure, properties and emerging applications
Cerium oxide nanoparticles (CeNPs) are versatile materials with unique and unusual properties that vary depending on their surface chemistry, size, shape, coating, oxidation states, crystallinity, dopant, structural and surface defects. This review details advances made over the past twenty years in the development of CeNPs and ceria-based nanostructures, the structural determinants affecting their activity, and translation of these distinct features into applications. The two-oxidation states of nanosized CeNPs (Ce3+/Ce4+) coexisting at the nanoscale level, facilitate formation of oxygen vacancies and defect states which confer extremely high reactivity and oxygen buffering capacity, and the ability to act as catalysts for oxidation and reduction reactions. However, the method of synthesis, surface functionalization, surface coating and defects are important factors in determining their properties. This review highlights the key properties of CeNPs, their synthesis, interactions and reaction pathways, and provides examples of emerging applications. Due to their unique properties, CeNPs have become quintessential candidates for catalysis, chemical mechanical planarization (CMP), sensing, biomedical applications and environmental remediation, with tremendous potential to create novel products and translational innovations in a wide range of industries. This review highlights the timely relevance and the transformative potential of these materials in addressing societal challenges and driving technological advancements across these fields.
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- Award ID(s):
- 2042544
- PAR ID:
- 10502879
- Publisher / Repository:
- Royal Society of Chemistry
- Date Published:
- Journal Name:
- Materials Horizons
- ISSN:
- 2051-6347
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1039/D4MH00055B
