Controllable synthesis of argentum decorated CuOx@CeO2 catalyst and its highly efficient performance for soot oxidation

Abstract

In this paper, CuOx@Ag/CeO2 catalysts were synthesized by simple wet-chemical method and equal volume impregnation method. The obtained catalysts were subjected to soot temperature programmed oxidation (soot-TPO) activity tests and were further characterized by various techniques such as X-ray diffraction (XRD), transmission electron microscopy/high-resolution transmission electron microscopy (TEM/HR-TEM), N2 physisorption, X-ray photoelectron spectroscopy (XPS) and H2-temperature programmed reduction (H2-TPR). The results show that CuOx@Ag/CeO2 synthesized presents well controlled core-shell structures, with nano-cube like Cu2O as the core and Ag decorated polycrystalline CeO2 grafting layers as the shell. Such core-shell structured CuOx@Ag/CeO2 can successfully construct a secondary oxygen delivery channel (CuOx → CeO2 → Ag) to effectively transfer bulk oxygen of the catalyst to the soot, resulting in its excellent soot oxidation activity compared to CuOx@CeO2. The potential benefiting effect by Ag introduction over Cu@Ag/Ce can be concluded as: (i) pumping lattice oxygen and accelerating gaseous O2 dissociation to generate significantly increased active surface oxygen content; (ii) modulating a moderate surface oxygen vacancies concentration to maintain more highly active O2– species.