Regulation of micro-environments by multi-metal promoters: A theoretical study on CO₂ activation over iron carbide catalysts

Essentially developing and regulating the unique electronic property of iron carbide catalysts involving multi-metal promoters to understand the structure–activity relationship of the CO₂ activation process is still a great challenge. Here, metals and transition metals were introduced as strategies for electronic structure regulation to theoretically understand the underlying nature of CO₂ adsorption and activation behaviors over Fe₃C catalysts. The distinctive micro-environment on the Fe₃C surface made it more conducive to CO₂ adsorption and activation compared to other Fe-based catalysts, which could be further enhanced by the addition of multi-metal promotors. The electronic properties of promoters well explained their influence on CO₂ adsorption behavior, while the binding energy of promoters had a good linear relationship with the CO₂ activation barrier. Specifically, there existed a distance effect by the doped multi-metals. When the doped metals were adjacent to each other, it would be more beneficial for CO₂ dissociation, and when they were far away from each other, it facilitated CO₂ adsorption. Moreover, Mn atom is a good choice for forming dual-atom catalysts, which could significantly increase the adsorption stability of CO₂ and facilitate the direct dissociation of CO₂.