Depth resolving of Fe 2p core-level photoemission during the CO2 hydrogenation reaction by lab-based soft and hard X-ray photoelectron spectroscopy

The dynamic of iron oxide based catalysts transitions during the CO2 2 hydrogenation reaction is highly complex and addressing the electronic structure of promoted Fe-based catalysts is a current critical challenge. Therefore, new methodologies are necessary to unveil the Fe phase distribution within surface to bulk resolution at the nanometer scale. The use of co-localized soft and hard X-ray photoelectron spectroscopies is an interesting approach to analyze the depth-dependency of Fe electronic structure by a non-destructive method. Herein, we characterize the Fe phase distribution in Na-Fe2O3 2 O 3 and Na-FeMnOx x catalysts, classical materials used in the CO2 2 hydrogenation reaction, at 3 and 15 nm from the catalyst surface. This methodology shows the evolution of Fe5C2 5 C 2 content as the analysis moves away from the surface, suggesting an oxidation process of carbide structures at the catalyst surface. The use of co-localized soft and hard X-ray photoelectron spectroscopy to resolve the electronic structure of catalysts provide better understanding of Fe phase transitions in promoted Fe-based catalyst for the direct CO2 2 hydrogenation reaction.