How the Balance between *CO and *H Intermediates in Dual Atom Catalysts Boosts Selectivity for Hydrocarbons

Abstract

The preparation of dual-atom catalysts (DACs) with unique capabilities requires in-depth microscopic theory for support. More precise electronic structure tuning leads to more accurate control over the adsorption of active intermediates, orbital interactions, and product selectivity. The distinctive structure of single-atom catalysts (SACs) aids in our understanding of the mechanisms behind carbon dioxide reduction reactions (CO2RR). Currently, there are various methods to modify the activity of SACs, among which DACs show particularly remarkable results, exhibiting superior CO selectivity. However, their selectivity towards hydrocarbons is relatively poor, and research on the mechanisms involved is correspondingly limited. Therefore, this paper aims to analyze the detailed mechanism of the key step CO→CHO (* representing the adsorption state) by establishing a comparison between 10 DAC models and the Fe-N4C SAC. We discuss the changes in the electronic structure of DACs compared to SACs and their microscopic interaction mechanisms with *CO and *H intermediates through thermodynamics, atomic populations (Mulliken) charge, density of states, and orbital charge distribution. The theoretical calculations also validate the reasons behind the excellent CO selectivity exhibited by DACs in experiments and identify the most favorable adsorption positions for H intermediates. Additionally, we discovered a special structural catalyst, FeM1-N6C, whose unique architecture may be more conducive to the synthesis of hydrocarbons. In summary, this study on the CO2RR mechanism of DAC catalysts aims to expedite the experimental development process and further advance research on DACs.