Probing Oxide Reduction and Phase Transformations at the Au-TiO2 Interface by Vibrational Spectroscopy

Abstract

transformations might be both thermally or light induced, however, the colloidal deposition synthesis of the Au/TiO 2 catalysts is clearly ruled out as cause for the formation of the reduced phase.

Mechanism of Laser-Induced Bulk and Surface Defect Generation in ZnO and TiO2 Nanoparticles: Effect on Photoelectrochemical Performance

“…Bandgaps became smaller for TiO2-AuNP composites upon ps-532-nm irradiation, and the decrease was more pronounced with more gold. We obtained slightly lower bandgaps for TiO2 with nominally 3 wt% AuNPs compared to neat TiO2, even without laser processing, indicative of rutilization by AuNP physisorption, in line with observations by Strunk et al 92 and Jovic et al 52 We explain the observed decrease of TiO2 bandgaps as a function of AuNP loading and ps-532-nm laser energy dose by electric field enhancements that are most pronounced near the interface between AuNP and TiO2, similar to our ZnO results (conceptual details are illustrated in Figure 6).…”

Au@TiO2 Core–Shell Composites for the Photocatalytic Reduction of CO2

“…Furthermore, the interface structure may be rather different in the core-shell system compared to samples prepared by the colloidal deposition route, in which reduction and rutile formation of the interface has recently been observed. [31] No mechanistic studies were conducted here, but the roughly equal amounts of CO and CH 4 formed photocatalytically may be indicative for the decomposition of ac ommon intermediate in the mechanism. One option may be acetaldehyde, suggested previouslya si ntermediate on bare TiO 2 .…”

“…Electromagnetic fields caused by light irradiation of the core–shell metal‐semiconductor‐metal structure may be very different from those caused in conventional Au/TiO 2 catalysts. Furthermore, the interface structure may be rather different in the core–shell system compared to samples prepared by the colloidal deposition route, in which reduction and rutile formation of the interface has recently been observed …”

“…Gold nanoparticles with an average diameter of 4 nm were deposited on different commercial TiO 2 samples using the colloidal deposition method. The synthesis using the commercial anatase material (≈300 m 2 g −1 , Huntsman P&A Germany) is reported in detail in a recent contribution . The synthesis of the Au/P25 catalyst was performed similarly, using commercial TiO 2 P25 (≈50 m 2 g −1 , Evonik Industries).…”

“…The synthesis using the commercial anatase material ( % 300 m 2 g À1 ,H untsman P&A Germany) is reported in detail in a recent contribution. [31] The synthesis of the Au/P25 catalyst was performed similarly,u sing commercial TiO 2 P25 ( % 50 m 2 g À1 , Evonik Industries). The gold loading on the anatase support was adjusted to 1wt%.O nt he P25 support, the loading of gold was 7.5 wt %.…”