Fe3O4/Fe1–xS Composites Enable Efficient Asymmetric C–C Coupling for CO2 Electrocatalytic Reduction to C2H6

CO 2 electrocatalytic reduction (CO 2 ER) to multicarbon products is an effective method to reduce carbon emissions and achieve sustainable energy development. However, most CO 2 ER systems mainly convert CO 2 into C 1 products, while the main electrocatalysts for generating C 2 products (such as C 2 H 4, C 2 H 6, C 2 H 5 OH, etc .) are Cu-based materials. Herein, a Fe-based composite (Fe 3 O 4 /Fe 1– x S) is constructed via in situ sulfidation of Fe 2 O 3 . Using 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF 6 ) acetonitrile (MeCN) solution as the electrolyte, the resultant Fe 3 O 4 /Fe 1– x S with an optimal component ratio exhibits excellent CO 2 ER activity and stability with a current density of 35 mA cm –2 and C 2 H 6 Faradaic efficiency (FE(C 2 H 6 )) of up to 67.5% at −1.60 V vs Ag/AgCl, which is much higher than the maximum values of pure Fe 3 O 4 (3.5%) and Fe 1– x S (36.7%). Experimental and theoretical results demonstrate that [Bmim]PF 6 can reduce the activation energy of CO 2 molecules and stabilize the *CO intermediate, while the synergistic effect of the electroactive Fe 3+ -substitution defects (Fe Fe • ) in nonstoichiometric Fe 1– x S and the Fe 3 O 4 /Fe 1– x S interface plays a critical role in promoting the protonation of the *CO intermediate to form *CHO, asymmetric *CO–*CHO coupling, and then continuous dehydration and protonation to generate C 2 H 6 . These findings provide valuable insights for improving the CO 2 ER performance of Fe-based catalysts for the production of multicarbon products.