Surface Iron Species in Palladium–Iron Intermetallic Nanocrystals that Promote and Stabilize CO₂ Methanation

Abstract

Abstract It is of pivotal importance to develop efficient catalysts and investigate the intrinsic mechanism for CO 2 methanation. Now, it is reported that PdFe intermetallic nanocrystals afforded high activity and stability for CO 2 methanation. The mass activity of fct ‐PdFe nanocrystals reached 5.3 mmol g −1 h −1 , under 1 bar (CO 2 :H 2 =1:4) at 180 °C, being 6.6, 1.6, 3.3, and 5.3 times as high as that of fcc ‐PdFe nanocrystals, Ru/C, Ni/C, and Pd/C, respectively. After 20 rounds of successive reaction, 98 % of the original activity was retained for PdFe intermetallic nanocrystals. Further mechanistic studies revealed that PdFe intermetallic nanocrystals enabled the maintenance of metallic Fe species via a reversible oxidation–reduction process in CO 2 methanation. The metallic Fe in PdFe intermetallic nanocrystals induced the direct conversion of CO 2 into CO* as the intermediate, contributing to the enhanced activity.