Direct XPS Evidence for Charge Transfer from a Reduced Rutile TiO₂(110) Surface to Au Clusters

Abstract

The electronic structures of Au clusters deposited on the stoichiometric and reduced rutile TiO 2 (110) surfaces were investigated by means of X-ray photoelectron spectroscopy. With the increasing Au thickness, the Au 4f binding energy shifts monotonically toward lower binding energy on the stoichiometric surface, essentially demonstrating a particle size effect. On the reduced surface, the Au 4f binding energy exhibits a monotonically downward shift with the increasing Au thickness below 1.5 Å, then unexpectedly shifts to higher binding energy when the Au thickness increases from 1.5 Å to 2 Å. The Au 4f binding energy shift observed on the reduced surface can be reasonably explained by a collective contribution from the particle size effect and the charge transfer from the reduced surface to Au clusters. Our results experimentally present direct XPS evidence for the charge transfer from the reduced TiO 2 (110) surface to Au clusters.

The Interfacial Nature of TiO2and ZnO Nanoparticles Modified by Gold Nanoparticles

“…37 The higher Au 4f XPS BE could also be due to a final state quantum size effect. [38][39][40] Because the size of Au particles could be decreased to a quantum size by sputtering, a quantum size effect should be discussed. At lower coverages of Au on TiO 2 (110) surface prepared in an UHV condition, it has been observed that the 4f7/2 XPS peak show ~ 0.5 eV higher BE than that of metallic Au, attributed to a final state screening effect.…”

“…At lower coverages of Au on TiO 2 (110) surface prepared in an UHV condition, it has been observed that the 4f7/2 XPS peak show ~ 0.5 eV higher BE than that of metallic Au, attributed to a final state screening effect. 39,40 Jiang et al reported a XPS evidence that on reduced TiO2 (110) surface charge transfer from the oxide support to Au also play a role in the XPS BE. 40 However, for the samples prepared in solution, the 4f7/2 XPS BE exhibits at much higher position than the BE induced by final-state quantum size or charge transfer effects.…”

Tracing Gold Nanoparticle Charge by Electrolyte−Insulator−Semiconductor Devices

“…[21][22][23] Scanning probe methods (STM/STS) generally require conductive supports combined with ultra-high-vacuum (UHV) conditions. The…”

Surface reaction of 2‐propanol on modified Keggin type polyoxometalates: In situ IR spectroscopic investigation of the surface acid–base properties

“…Furthermore, gold containing catalysts have been extensively studied within the last two decades and are known to be suitable for alcohol oxidation [4,5]. It was shown that the catalytic properties of the Au/TiO 2 catalysts are not only affected by the morphology of the metal oxide [6] and the size of the gold particles [7], but to a considerable degree by the gold deposition process on the metal oxide substrate [8]. Slight changes of process parameters like temperature, concentration, or precipitation and aging give different Au/TiO 2 composites [6][7][8].…”

“…It was shown that the catalytic properties of the Au/TiO 2 catalysts are not only affected by the morphology of the metal oxide [6] and the size of the gold particles [7], but to a considerable degree by the gold deposition process on the metal oxide substrate [8]. Slight changes of process parameters like temperature, concentration, or precipitation and aging give different Au/TiO 2 composites [6][7][8]. The susceptibility of the deposition process to varying reaction conditions affects the reproducibility of the synthesis and has led to partly contradicting investigations concerning the activity of the Au/TiO 2 composites [9].…”