Enhanced Bonding of Silver Nanoparticles on Oxidized TiO₂(110)

Abstract

The nucleation and growth of silver nanoclusters on TiO 2 (110) surfaces with on-top O adatoms (oxidized TiO 2 ), surface O vacancies and H adatoms (reduced TiO 2 ) have been studied. From the interplay of scanning tunneling microscopy/photoelectron spectroscopy experiments and density functional theory calculations, it is found that silver clusters are much more strongly bonded to oxidized TiO 2 (110) surfaces than to reduced TiO 2 (110) model supports. It is shown that electronic charge can be transferred from silver clusters to the oxidized TiO 2 (110) surface, as evidenced by the reappearance of the Ti3d defect state upon silver exposure. Furthermore, from both scanning tunneling microscopy data and density functional theory calculations the most favorable adsorption site of silver monomers on oxidized TiO 2 ( 110) is one that bridges between on-top O adatoms and regular surface O atoms nearby. † Part of the "D. Wayne Goodman Festschrift".

Ag fractals formed on top of a porous TiO2 thin film

“…oxygen vacancies), which mediate the clusters' growth on the surface of TiO 2 . As claimed by Hansen et al , the interaction of Ag clusters with TiO 2 is stronger as the latter is more oxidized. However, in this work, Ag atoms migrated significantly to the surface to form the fractal clusters, which was probably the result of the fairly low chemical interaction of Ag clusters to the roughly stoichiometric matrix.…”

“…This aggregation phenomenon, commonly referred as diffusion‐limited aggregation (DLA), is known to be far from equilibrium, and predicts that fractal geometries can emerge from homogeneous media, such as the case of the as‐deposited sample (Ag embedded in TiO 2 ). Under high temperature conditions, Ag atoms appear on the surface, owing to the segregation process, indicating a weak interaction with the matrix . These adatoms, with high mobility, form a cluster at some singular point of the surface (a nucleation center), and certain area around this cluster becomes devastated because all of them stick to the cluster.…”

Understanding the Nucleation and Growth of Metals on TiO2: Co Compared to Au, Ni, and Pt

“…Moreover, the binding energy of Au on O-TiO 2 is lower than that of Ni or Co, and this reflects the experimental behavior in which the Au clusters grown on O-TiO 2 have greater average heights (4.8 ± 2.3 Å) than Co (3.0 ± 0.4 Å) or Ni (2.7 ± 1.5 Å), which have similar heights (Table 3). Likewise, STM studies of Ag 80 and Au 79 clusters on oxidized TiO 2 (110) have reported stronger bonding of the metal to the oxidized surface compared to the vacuum-annealed surface. 80 This increased binding in the presence of oxygen is reflected in the experimental observation ( Figure 6) that the average particle size for all investigated metals is smaller on the oxidized surface.…”

“…Likewise, STM studies of Ag 80 and Au 79 clusters on oxidized TiO 2 (110) have reported stronger bonding of the metal to the oxidized surface compared to the vacuum-annealed surface. 80 This increased binding in the presence of oxygen is reflected in the experimental observation ( Figure 6) that the average particle size for all investigated metals is smaller on the oxidized surface.…”

X-ray spectroscopies studies of the 3d transition metal oxides and applications of photocatalysis

“…Commonly, it was investigated in a model system and was constructed and studied on single crystal samples, while the scanning tunneling microscope was always employed to monitor relevant properties. 59,60 Moreover, the theoretical simulations indicated that this kind of bond can be good electron trap, where the extra electrons from the O can occupy the σ* states. Consequently, the drastic change on the band structures can be predicted.…”