A methodical approach to investigate Ni@C CO₂ methanation catalysts obtained by thermal decomposition of nickel MOFs using hard X-rays is established and applied. The procedure involves high-energy-resolution X-ray absorption near-edge structure spectroscopy and X-ray emission spectroscopy in combination with ab initio FEFF calculations.

Abstract

A new approach for the characterization of CO₂ methanation catalysts prepared by thermal decomposition of a nickel MOF by hard X-ray photon-in/photon-out spectroscopy in form of high energy resolution fluorescence detected X-ray absorption near edge structure spectroscopy (HERFD-XANES) and valence-to-core X-ray emission (VtC-XES) is presented. In contrast to conventional X-ray absorption spectroscopy, the increased resolution of both methods allows a more precise phase determination of the final catalyst, which is influenced by the conditions during MOF decomposition.