Temperature-Dependent Local Structural Properties of Redox Pt Nanoparticles on TiO2 and ZrO2 Supports

• Published in: Catalysis letters Vol. 145; no. 3; pp. 971 - 983
• Main Authors: Jeong, E.-S., Park, C.-I., Jin, Zhenlan, Hwang, I.-H., Son, J.-K., Kim, Mi-Young, Choi, Jae-Soon, Han, Sang-Wook
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01-03-2015; Springer Nature B.V; Springer
• Subjects: Bonding strength; Catalysis; Chemistry; Chemistry and Materials Science; Coordination numbers; EXAFS, XANES; Fine structure; Industrial Chemistry/Chemical Engineering; metal support interaction; Nanoparticles; Organometallic Chemistry; oxidation catalysts; Physical Chemistry; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Platinum; Pt catalysts; Silicon dioxide; SiO2, TiO2; Stability analysis; Temperature dependence; Thermal stability; Titanium; Titanium dioxide; X ray absorption; Zirconium dioxide; Metal support interaction; Pt catalysts; EXAFS, XANES; ZrO; Oxidation catalysts; SiO; TiO
• ISSN: 1011-372X; 1572-879X
• DOI: 10.1007/s10562-015-1483-x

This study examined the local structural properties of Pt nanoparticles on SiO
2
, TiO
2
–SiO
2
, and ZrO
2
–SiO
2
supports to better understand the impact of oxide-support type on the performance of Pt-based catalysts. In situ X-ray absorption fine structure (XAFS) measurements were taken for the Pt L
3
-edge in a temperature range from 300 to 700 K in He, H
2
, and O
2
gas environments. The XAFS measurements demonstrated that Pt atoms were highly dispersed on TiO
2
–SiO
2
and ZrO
2
–SiO
2
forming pancake-shaped nanoparticles, whereas Pt atoms formed larger particles of hemispherical shapes on SiO
2
supports. Contrary to the SiO
2
case, the coordination numbers for Pt, Ti, and Zr around Pt atoms on the TiO
2
–SiO
2
and ZrO
2
–SiO
2
supports were nearly constant from 300 to 700 K under the different gas environments. These results are consistent with the improvements in thermal stability of Pt nanoparticles achieved by incorporating TiO
2
or ZrO
2
on the surface of SiO
2
supports. XAFS analysis further indicated that the enhanced dispersion and stability of Pt were a consequence of the strong metal support interaction via Pt–Ti and Pt–Zr bonds.
Graphical Abstract
From XANES measurements, oxygen coordination numbers of a Pt atom on different supports of (a) SiO
2
, (b) TiO
2
-SiO
2
, and (c) ZrO
2
-SiO
2
were determined. As temperature increases, oxygen coordination numbers gradually decreased in a He gas, whereas it is dramatically decreases in an H
2
gas.