The noble metals M (M = Pd, Ag, Au) decorated CeO₂ catalysts derived from solution combustion method for efficient low-temperature CO catalytic oxidation: effects of different M loading on catalytic performances

Abstract

The noble metal nanoparticles have attracted attention due to their excellent catalytic performance for CO oxidation at low temperatures. M-CeO2 (M = Pd, Ag, Au) catalysts with different atomic ratios of M/Ce were deposited via solution combustion method. Among them, 3 at% Pd-CeO2, 5 at% Ag-CeO2 and 1 at% Au-CeO2 catalysts have better catalytic performances. Especially, 5 at% Ag-CeO2 catalyst shows better low-temperature CO oxidation performance. The catalytic activity for CO oxidation follows the follows the following sequence: 5 at% Ag-CeO2 (T50 = 69 °C) > 3 at% Pd-CeO2 (T50 = 99 °C) >1 at% Au-CeO2 (T50 = 115 °C). Meanwhile, the catalysts are characterized by means of powder x-ray diffraction, scanning electron microscope, transmission electron microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, Brunauer–Emmett–Teller and H2-TPR. The characterization results show that the 5 at% Ag-CeO2 catalyst has excellent catalytic activity due to the good dispersion of Ag nanoparticles, the specific surface area of the material, and the reduction catalyst between different valence ions. Moreover, the surface of the catalyst enhances the mutual synergy, effectively promotes the generation of oxygen vacancies, and increases the active oxygen content of the catalyst surface. Finally, the catalytic mechanism of M-CeO2 catalysts is summarized.