The roles of various Fe–Cu bimetallic nanoclusters in controlling the C2 selectivity for the CO reduction reaction – a DFT study

Abstract

The unique microstructure of the Cu₁₃ nanocluster with distinct catalytic properties from general metals has been used to study the selectivity effect on oxygenated hydrocarbons. The strong synergistic promotion of Fe–Cu bimetallic nanocatalysts has been used to convert CO₂ or CO to olefins via selective reduction. Unveiled using DFT, we have characterized the CO reduction capabilities of a series of Fe–Cu bimetallic nanocatalysts and further investigated to search for the possible intermediates along the CO reduction pathway. Fe_nCu_13−n clusters with different compositions (n = 1, 2, 7, 11 and 12) are selected to represent the Cu dominant, the equal ratios, and the Fe dominant conditions in the simulations. Only the Fe-dominant clusters, particularly Fe₇Cu₆ and Fe₁₁Cu₂, show a preference for the formation of the COCHO intermediate. The improvement in selectivity is crucial to the successful design of catalytic systems for carbon-neutral processes. Thus, we incorporated carbon nanotubes (CNTs) to stabilize Fe₇Cu₆ and Fe₁₁Cu₂ nanoclusters, with the goal of enhancing the reactivity of the CORR. Compared to the isolated nanoclusters, the Fe₁₁Cu₂/CNT not only reduces the activation energy for CO⋯CHO bond formation and the reaction energy for COCHO intermediate formation but also exhibits more stable thermodynamic properties for ethanol generation.