Size-Dependent Pt-TiO₂ Strong Metal–Support Interaction

Abstract

The strong metal–support interaction (SMSI) is one of the most important concepts in heterogeneous catalysis. Herein we report a study of Pt-TiO2 SMSI using Pt/rutile TiO2(110) model catalysts with different Pt particle sizes by means of X-ray photoelectron spectroscopy, ion scattering spectroscopy, and the adsorption of probe molecules. The acquired results unambiguously demonstrate a size dependence of the Pt-TiO2 SMSI, in which SMSI occurs barely between supported Pt clusters and the TiO2(110) substrate but obviously between supported Pt nanoparticles and the TiO2(110) substrate. Such a size-dependent SMSI could be associated with size-dependent electronic structures of the supported Pt particles. These results highlight the sensitivity of the SMSI to the size of supported metal particles, which greatly advances the fundamental understanding.

Structure Sensitivity of Au‐TiO2 Strong Metal–Support Interactions

“…Therefore, the observed positive shifts in the Au 4f binding energy of Au/TiO 2 ‐H500 catalysts should result from the charge transfer from capsulated Au NPs to capsulating TiO 2− x overlayers. Similar charge transfer was previously observed from capsulated Pt NPs to capsulating TiO 2− x overlayers due to the Pt‐TiO 2 SMSI [21] . The Au 4f binding energy shift amplitudes vary with both the size of supported Au NPs and the TiO 2 facets in the same trends to the SMSI effect.…”

“…[20] Charge transfer occurs obviously from surface oxygen vacancies of reduced TiO 2 surface to supported Au NPs but is negligible between supported Au NPs and stoichiometric TiO 2 surface.T herefore,the observed positive shifts in the Au 4f binding energy of Au/TiO 2 -H500 catalysts should result from the charge transfer from capsulated Au NPs to capsulating TiO 2Àx overlayers.Similar charge transfer was previously observed from capsulated Pt NPs to capsulating TiO 2Àx overlayers due to the Pt-TiO 2 SMSI. [21] TheA u4f binding energy shift amplitudes vary with both the size of supported Au NPs and the TiO 2 facets in the same trends to the SMSI effect. Supported on the same type of TiO 2 support, 5nmA uN Ps exhibit larger Au 4f binding energy shifts and more extensive Au-TiO 2 SMSI than 2nmA uN Ps;w ith and O1sbinding energy shifts of Au/TiO 2 -fresh catalysts after H500 pretreatments.…”

Structure Sensitivity of Au‐TiO2 Strong Metal–Support Interactions

“…[20] Charge transfer occurs obviously from surface oxygen vacancies of reduced TiO 2 surface to supported Au NPs but is negligible between supported Au NPs and stoichiometric TiO 2 surface.T herefore,the observed positive shifts in the Au 4f binding energy of Au/TiO 2 -H500 catalysts should result from the charge transfer from capsulated Au NPs to capsulating TiO 2Àx overlayers.Similar charge transfer was previously observed from capsulated Pt NPs to capsulating TiO 2Àx overlayers due to the Pt-TiO 2 SMSI. [21] TheA u4f binding energy shift amplitudes vary with both the size of supported Au NPs and the TiO 2 facets in the same trends to the SMSI effect. Supported on the same type of TiO 2 support, 5nmA uN Ps exhibit larger Au 4f binding energy shifts and more extensive Au-TiO 2 SMSI than 2nmA uN Ps;w ith [22] TheA up article size-dependent Au NP -to-TiO 2Àx charge transfer at the TiO 2Àx -Au NP interface can be associated with the size-dependent electronic structures of Au NPs.Resulted from the interplay of quantum-size and surface effect, [23] the lattice contracts,a nd the dc harge at the metal atom site depletes relative to the bulk metal as the size of metal particles decreases.S upported Au NPs of 2-3 nm were previously reported to exhibit such am etal-to-nonmetal transition.…”

Pt/TiO2 Catalyzed Hydrogenation of Benzoic Acid with Unprecedented High Activity

“…showing that the H 2 treatment of Pt/TiO 2 did not induce the severe coverage of Pt surface by TiO x , which may be due to pre-nucleation reduction method for the synthesis of the parent Pt/TiO 2 [30,31].…”

“…It is noteworthy to mention that the activity of Pt/TiO 2 was much lower in water than in hexane, which is possibly related with the active sites blocking and low solubility of H 2 in water [16,18,28]. [30,31].…”