Metal-organic framework templated Pd/CeO2@N-doped carbon for low-temperature CO oxidation.

Abstract

A new Pd/Ce based metal–organic framework is designed and synthesized as a self-sacrificial template for fabrication of an efficient catalyst for CO oxidation. The catalyst obtained by thermal annealing at 700 °C (Pd/CeO2@NC-700) is composed of N-doped carbon with embedded Pd and CeO2 nanoparticles, which are highly dispersed and closely connected in the N-doped carbon; the high Pd loading (33.7 wt%) and the coupling between Pd and the CeO2 phase synergistically boost the CO oxidation performance. The Pd/CeO2@NC-700 catalyst exhibits a 100% conversion temperature of 89 °C and excellent long-term stability. By combining structural characterization with density functional theory calculations, two possible CO oxidation pathways of TPB and TOP are revealed, in which the adsorbed O2 directly dissociates to O* atoms and activates CO* molecules. The transfer of O* between Pd and Ce (TPB) or Pd and Pd (TOP) facilitates the formation of intermediates and finally results in the production of CO2. This work provides a new insight into the development of novel efficient catalysts for CO oxidation based on metal–organic frameworks.