Synergistic effect of Cu and Ag on porous (Cu, Ag) co-doped CeO2 nanosheets for low-temperature CO oxidation

Abstract

CeO₂ with porous nanosheet structure was prepared by changing the calcination environment. The prepared CeO₂ nanosheets had high specific surface area and porosity, which was suitable for supporting other active components. By the same synthesis conditions, a small amount of Cu and Ag was introduced into the synthesis system of CeO₂ nanosheets respectively. The introduction of Cu or Ag did not significantly change the morphology of the prepared CeO₂ nanosheets, but it notably improved the catalytic activity for CO oxidation. Therefore, considering the significant improvement of catalytic performance caused by the single doping of Cu or Ag, (Cu, Ag) were co-doped into the CeO₂ system. The analysis of physical structure (XRD, BET, SEM and TEM) and surface chemical properties (XPS, Raman and H₂-TPR) showed that the (Cu, Ag) co-doping not only improved the dispersion of Cu and Ag species on the catalyst surface, but also increased the Ag⁰ and oxygen vacancies on the catalyst surface. The smaller Ag⁰ crystallite size and the abundant oxygen vacancies made the catalyst easier to activate O₂ at low temperature, so the activity of the catalyst at low temperature was significantly enhanced compared to the CeO₂ singly doped with Cu or Ag. At the same time, the high dispersion of Cu-Ag species was conducive to electron transfer between Cu-Ag species and CeO₂ support.