AuPd/TiO2 Catalysts in the CO Oxidation: Insights into the Synthesis Procedure and In-situ Spectroscopy Studies

• Published in: Topics in catalysis Vol. 68; no. 14; pp. 1725 - 1746
• Main Authors: Araiza, Daniel G., Fernández, Misael, Sánchez-Ugalde, Mariana, Miranda, Aida, Solís-Casados, Dora A., Maturano-Rojas, Viridiana, Zanella, Rodolfo
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.09.2025; Springer Nature B.V
• Subjects: Ambient temperature; Bimetals; Carbon monoxide; Catalysis; Catalysts; Catalytic converters; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Gold; Heat treatment; High temperature; Industrial Chemistry/Chemical Engineering; Intermetallic compounds; Low temperature; Nanoparticles; Original Paper; Oxidation; Palladium; Pharmacy; Physical Chemistry; Raman spectroscopy; Spectrum analysis; Titanium dioxide; Intermetallic Au-Pd NPs; TiO; CO oxidation; In-situ spectroscopy; reducibility
• ISSN: 1022-5528; 1572-9028
• DOI: 10.1007/s11244-025-02051-w

A series of bimetallic AuPd/TiO 2 catalysts (Au/Pd = 1) were prepared through either the impregnation or the deposition-precipitation in urea (DPU) approach and tested in the CO oxidation reaction. Among these, the sample synthesized through a sequential impregnation (Pd) followed by DPU (Au), with an intermediate thermal treatment in air, presented a remarkable CO conversion at sub-ambient temperatures and an enhanced catalytic stability, compared to the monometallic samples. The ex-situ characterization revealed that the synthesis procedure led to the formation of well-dispersed bimetallic AuPd nanoparticles over the TiO 2 support. The in-situ characterization helped to propose that bimetallic NPs were composed of an intermetallic Au-Pd phase with both atoms available in the surface. Both in-situ FTIR and UV-vis spectroscopies helped to recognize the active sites during the reaction: Au in close interaction with the TiO 2 at low temperatures, and step/edges Pd sites at high temperatures. Finally, the pivotal role of the TiO 2 reducibility in the CO oxidation reaction, promoted by the bimetallic AuPd NPs, was determined through in-situ Raman spectroscopy.