Halogen poisoning effect of Pt-TiO₂ for formaldehyde catalytic oxidation performance at room temperature

Xiaofeng ZHU, Bei CHENG, Jiaguo YU, Wing Kei HO

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Abstract

Catalytic decomposition of formaldehyde (HCHO) at room temperature is an important method for HCHO removal. Pt-based catalysts are the optimal catalyst for HCHO decomposition at room temperature. However, the stability of this catalyst remains unexplored. In this study, Pt-TiO₂ (Pt-P25) catalysts with and without adsorbed halogen ions (including F⁻, Cl⁻, Br⁻, and I⁻) were prepared through impregnation and ion modification. Pt-TiO₂ samples with adsorbed halogen ions exhibited reduced catalytic activity for formaldehyde decomposition at room temperature compared with the Pt-TiO₂ sample; the catalytic activity followed the order of F-Pt-P25, Cl-Pt-P25, Br-Pt-P25, and I-Pt-P25. Characterization results (including XRD, TEM, HRTEM, BET, XPS, and metal dispersion) showed that the adsorbed halogen ions can poison Pt nanoparticles (NPs), thereby reducing the HCHO oxidation activity of Pt-TiO₂. The poison mechanism is due to the strong adsorption of halogen ions on the surface of Pt NPs. The adsorbed ions form a coordination bond with surface Pt atoms by transferring surplus electrons into the unoccupied 5d orbit of the Pt atom, thereby inhibiting oxygen adsorption and activation of the Pt NP surface. Moreover, deactivation rate increases with increasing diameter of halogen ions. This study provides new insights into the fabrication of high-performance Pt-based catalysts for indoor air purification. Copyright © 2015 Published by Elsevier B.V.
Original languageEnglish
Pages (from-to)808-814
JournalApplied Surface Science
Volume364
Early online dateDec 2015
DOIs
Publication statusPublished - 2016

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Halogens
Catalytic oxidation
Formaldehyde
Ions
Catalysts
Poisons
Temperature
Nanoparticles
Decomposition
Catalyst activity
Air purification
Adsorption
Atoms
Impregnation
Orbits
X ray photoelectron spectroscopy
Metals
Chemical activation
Oxygen
Transmission electron microscopy

Bibliographical note

Zhu, X., Cheng, B., Yu, J., & Ho, W. (2016). Halogen poisoning effect of Pt-TiO₂ for formaldehyde catalytic oxidation performance at room temperature. Applied Surface Science, 364, 808-814.

Keywords

  • Halogen poisoning
  • Pt-TiO₂
  • Formaldehyde
  • Catalytic oxidation