The influence of oxygen vacancy and Ce³⁺ ion positions on the properties of small gold clusters supported on CeO_2−x(111)

Abstract

We studied the influence of oxygen vacancies on small Au clusters supported on CeO2 using dispersion-corrected density functional theory (DFT-D3).

Comparative study of single-atom gold and iridium on CeO2{111}

“…7) confirms that a sharp majority-polarised peak does indeed arise below the lower edge of the main Ce 4 f band, dropping beneath the Fermi level and accommodating precisely one electron, as noted in several prior works. 6,[8][9][10]15 This charge has previously been explained as originating from depopulation of the Au 6s state, 6 but we note here that although one finds an unoccupied peak of Au 6s character at around 1.6 eV above the Fermi level, its weight (including both spin components) is sufficient to account for only a little more than a single electron, not two. Moreover, occupied states of Au 6s character are distributed throughout the energy range associated with the main valence complex (somewhat weighted towards the extremes of that range) and retain charge amounting to at least four fifths of an electron.…”

“…This may at first seem a little concerning, but is most likely a consequence of (a) the finite energetic smearing applied when calculating occupancies in our calculations and (b) some slight hybridisation between neighbouring cerium ions mediated via their shared covalent interactions with the intervening oxygen ion. A higher value of U, as used in most previous studies, 5,[8][9][10][11][12][13][14][15] would undoubtedly tend to suppress both effects, resulting in less of the spurious spin leakage seen here. In practice, however, the error introduced into our calculated geometry and total energy should be minimal.…”

“…1,2 Indeed, it has been shown that several SACs (e.g. Pt 1 /FeO x , 3 Au 1 /CeO 2 , [4][5][6][7][8][9][10][11][12][13][14][15] Ir 1 /CeO 2 , 16 etc.) are thermodynamically stable under plausible reaction conditions, and that the active precious-metal adatoms neither aggregate into larger nanoparticles nor diffuse into the underlying oxide.…”

Influence of Co-Precipitation Agent on the Structure, Texture and Catalytic Activity of Au-CeO2 Catalysts in Low-Temperature Oxidation of Benzyl Alcohol

“…From among numerous ceria-based systems, the catalysts containing gold nanoparticles have attracted particular attention and have been successfully used in different catalytic processes (e.g., Water-Gas Shift reaction [9], oxidation of CO [10,11], alcohols [12][13][14] and formaldehyde [15]). In terms of selective oxidation of alcohols, it has been established that one of the most important factors affecting the activity and selectivity of Au/CeO 2 catalysts is the size of the supported gold nanoparticles [11,16] and the concentration of lattice defects in the ceria support [17]. These two factors have been considered as the key guidelines on the development of new methods for the synthesis of highly active ceria-based gold catalysts.…”

Au/CeO2 Photocatalyst for the Selective Oxidation of Aromatic Alcohols in Water under UV, Visible and Solar Irradiation

“…According to the literature, the most important factors influencing the activity and selectivity of Au/CeO 2 as thermal catalysts for the partial oxidation of benzyl alcohols are the size of the supported gold nanoparticles [17] and the concentration of lattice defects in the ceria support [18]. Wolsky et al report that the use of NaOH as precipitation (or coprecipitation) agent instead of urea or hexamethylenetetramine in the CeO 2 preparation has a significant impact on the structure, texture and catalytic properties of Au/CeO 2 catalysts resulting beneficial in the formation of small and uniform gold nanoparticles possessing enhanced catalytic activity s in low-temperature oxidation of benzyl alcohol [19].…”