Fine Structural Characterization of Zinc and Iron Atoms in Zinc Ferrite Nanocatalysts for CO_(2) Decomposition Using XANES/EXAFS

摘要

The decomposition of CO_(2) over zinc ferrite nanoparticles (ZFNs) at 573 K was studied and the oxidation states of Fe and Zn species were investigated using XANES/EXAFS of fresh and reduced ZFNs. Oxygen deficiency in ZFNs was obtained by reducing the ZFNs catalyst in hydrogen. Decomposition of CO_(2) was occurred by the incorporation of oxygen in the vacancies of ZFNs and deposition of carbon occurred on the surface. The deposited carbon was converted into methane upon treatment with hydrogen while regenerating the reduced ZFNs to oxygen deficient ZNFs. The pre-edge XANES spectra of Fe in ZFNs exhibit an absorbance feature at 7115 eV for the 1s to 3d transition. The EXAFS data showed that the fresh ZFNs had two central Fe atoms coordinated by primarily Fe-O and Fe-Fe with bond distances of 1.89 A and 3.05 A, respectively.