Surface-structure sensitivity of CeO₂ nanocrystals in photocatalysis and enhancing the reactivity with nanogold

Journal Article · Fri Jun 19 00:00:00 EDT 2015 · ACS Catalysis

DOI:https://doi.org/10.1021/acscatal.5b00620· OSTI ID:1222610

Lei, Wanying ^[1]; Zhang, Tingting ^[1]; Gu, Lin ^[2]; Liu, Ping ^[3]; Rodriguez, José A. ^[3]; Liu, Gang ^[1]; Liu, Minghua ^[1]

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1. National Center for Nanoscience and Technology, Beijing (China)
2. Chinese Academy of Sciences, Beijing (China)
3. Brookhaven National Lab. (BNL), Upton, NY (United States)

Structure–function correlations are a central theme in heterogeneous (photo)catalysis. In this research, using aberration-corrected scanning transmission electron microscopy (STEM), the atomic surface structures of well-defined one-dimensional (1D) CeO₂ nanorods (NRs) and 3D nanocubes (NCs) are directly visualized at subangstrom resolution. CeO₂ NCs predominantly expose the {100} facet, with {110} and {111} as minor cutoff facets at the respective edges and corners. Notably, the outermost surface layer of the {100} facet is nearly O-terminated. Neither surface relaxations nor reconstructions on {100} are observed, indicating unusual polarity compensation, which is primarily mediated by near-surface oxygen vacancies. The surface of CeO₂ NRs is highly stepped, with the enclosed {110} facet exposing Ce cations and O anions on terraces. On the basis of STEM profile-view imaging and electronic structure analysis, the photoreactivity of CeO2 nanocrystals toward aqueous methyl orange degradation under UV is revealed to be surface-structure-sensitive, following the order: {110} >> {100}. The underlying surface-structure sensitivity can be attributed to the variation in low-coordinate surface cerium cations between {110} and {100} facets. To further enhance light absorption, Au nanoparticles (NPs) are deposited on CeO₂ NRs to form Au/CeO₂ plasmonic nanocomposites, which dramatically promotes the photoreactivity that is Au particle size- and excitation light wavelength-dependent. The mechanisms responsible for the enhancement of photocatalytic activity are discussed, highlighting the crucial role of photoexcited charge carrier transfer.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: 51272048
• OSTI ID: 1222610
• Report Number(s): BNL-108402-2015-JA; R&D Project: CO009; KC0302010
• Journal Information: ACS Catalysis, Vol. 5, Issue 7; ISSN 2155-5435
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
surface structure
CeO2
aberration-corrected STEM
photocatalysis
surface plasmon resonance
nanogold