High-performance and long-term stability of mesoporous Cu-doped TiO2 microsphere for catalytic CO oxidation

Wen-Ta Yang; Chin Jung Lin; Tiziano Montini; Paolo Fornasiero; Sofia Ya; Sofia Ya Hsuan Liou

doi:10.1016/j.jhazmat.2020.123630

High-performance and long-term stability of mesoporous Cu-doped TiO₂ microsphere for catalytic CO oxidation

J Hazard Mater. 2021 Feb 5:403:123630. doi: 10.1016/j.jhazmat.2020.123630. Epub 2020 Aug 11.

Authors

Wen-Ta Yang¹, Chin Jung Lin², Tiziano Montini³, Paolo Fornasiero³, Sofia Ya⁴, Sofia Ya Hsuan Liou⁵

Affiliations

¹ Department of Geosciences, National Taiwan University, Taipei 106, Taiwan; Research Center for Future Earth, National Taiwan University, Taipei 106, Taiwan.
² Department of Environmental Engineering, National I-Lan University, I-Lan 260, Taiwan.
³ Department of Chemical and Pharmaceutical Sciences, University of Trieste, 34127 Trieste, Italy.
⁴ Department of Geosciences, National Taiwan University, Taipei 106, Taiwan; Research Center for Future Earth, National Taiwan University, Taipei 106, Taiwan; Department of Environmental Engineering, National I-Lan University, I-Lan 260, Taiwan; Department of Chemical and Pharmaceutical Sciences, University of Trieste, 34127 Trieste, Italy.
⁵ Department of Geosciences, National Taiwan University, Taipei 106, Taiwan; Research Center for Future Earth, National Taiwan University, Taipei 106, Taiwan. Electronic address: yhliou@ntu.edu.tw.

PMID: 33264857
DOI: 10.1016/j.jhazmat.2020.123630

Abstract

Although the low-temperature reaction mechanism of catalytic CO oxidation reaction remains unclear, the active sites of copper play a crucial role in this mechanism. One-step aerosol-assisted self-assembly (AASA) process has been developed for the synthesis of mesoporous Cu-doped TiO₂ microspheres (CuTMS) to incorporate copper into the TiO₂ lattice. This strategy highly enhanced the dispersion of copper from 41.10 to 83.65%. Long-term stability of the as-synthesized CuTMS materials for catalytic CO oxidation reaction was monitored using real-time mass spectrum. Isolated CuO and Cu-O-Ti were formed as determined by X-ray photoelectron spectroscopy (XPS). The formation of the Cu-O-Ti bonds in the crystal lattice changes the electron densities of Ti(IV) and O, causing a subsequent change in Ti(III)/Ti(IV) and O_non/O_Total ratio. 20CuTMS contained the highest lattice distortion (0.44) in which the O_non/O_Total ratio is lowest (0.18). This finding may be attributed to the absolute formation of the Cu-O-Ti bonds in the crystal lattice. However, the decrease of Ti(III)/Ti(IV) ratio to about 0.35 of 25CuTMS was caused by the CuO cluster formation on the surface. N₂O titration-assisted H₂ temperature-programmed reduction and in-situ Fourier transform infrared spectroscopy revealed the properties of copper and effects of active sites.

Keywords: Cu-O-Ti; one-step AASA; real-time mass; well-dispersed.