Synergistic effect of Fe-Mn bimetallic sites with close proximity for enhanced CO2 hydrogenation performance

The Fe-Mn bimetallic catalyst is a potential candidate for the conversion of CO₂ into value-added chemicals. The interaction between the two metals plays a significant role in determining the catalytic performance, however which remains controversial. In this study, we aim to investigate the impact of tuning the proximity of Fe-Mn bimetallic catalysts with similar nanoparticle size. And its effect on the physicochemical properties of the catalysts and corresponding performance were investigated. It was found that closer Fe-Mn proximity resulted in enhanced CO₂ hydrogenation activity and inhibited CH₄ formation. The physiochemical properties of prepared catalysts were characterized using X-ray diffraction, H₂ temperature programmed reduction, and X-ray photoelectron spectroscopy, revealing that a closer Fe-Mn distance promoted electron transfer from Mn to Fe, thereby facilitating Fe carburization. The adsorption behavior of CO₂ and the identification of reaction intermediates were analyzed using CO₂-temperature programed desorption and in situ Fourier transform infrared spectroscopy, confirming the intimate Fe-Mn sites contributed to CO₂ adsorption and the formation of HCOO* species, ultimately leading to increased CO₂ conversion and hydrocarbon production. The discovery of a synergistic effect at the intimate Fe-Mn sites in this study provides valuable insights into the relationship between active sites and promoters.