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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. [ABSTRACT FROM AUTHOR]

The interaction between a promoter and an active metal crucially impacts catalytic performance. Nowadays, the influence of promoter contents and species has been intensively considered. In this study, we investigate the effect of the iron (Fe)–zinc (Zn) proximity of Fe–Zn bimetallic catalysts on CO2 hydrogenation performance. To eliminate the size effect, Fe2O3 and ZnO nanoparticles with uniform size are first prepared by the thermal decomposition method. By changing the loading sequence or mixing method, a series of Fe–Zn bimetallic catalysts with different Fe–Zn distances are obtained. Combined with a series of characterization techniques and catalytic performances, Fe–Zn bimetallic proximity for compositions of Fe species is discussed. Furthermore, we observe that a smaller Fe–Zn distance inhibits the reduction and carburization of the Fe species and facilitates the oxidation of carbides. Appropriate proximity of Fe and Zn (i.e., Fe1Zn1-imp and Fe1Zn1-mix samples) results in a suitable ratio of the Fe5C2 and Fe3O4 phases, simultaneously promoting the reverse water–gas shift and Fischer–Tropsch synthesis reactions. This study provides insight into the proximity effect of bimetallic catalysts on CO2 hydrogenation performance. [ABSTRACT FROM AUTHOR]