Improving the Activity and Selectivity of the CO₂ Reduction Reaction with 2D Ferroelectric Materials

With the great concern of global warming, removing CO₂ from the atmosphere and converting it into useful commercial chemical products through the electrochemical CO₂ reduction reaction has attracted intense interest. Two-dimensional (2D) materials such as Ti₂CO₂ and transition metal (TM)-doped graphene have been shown to be effective catalysts for the CO₂ reduction reaction (CO2RR). However, due to the complexity of the CO2RR, various species can be produced as products, indicating a poor selectivity of the reaction. Furthermore, ways to overcome limiting scaling relationships and break the Sabatier principle are also desired. To solve these problems, we investigated using 2D ferroelectric (FE) materials, which show a spontaneous electric polarization that is switchable by an electric field, as substrates for CO2RR active catalysts. By switching the polarization, the activity of the surface can be changed, leading to a way to alter the adsorption strength or stability dynamically and overcoming the limiting Sabatier principle. Using density functional theory calculations, we first studied the 2D MXene Y₂CO₂ and found that switching the polarization results in different pathways for the reduction of CO₂ to methanol. Second, we studied heterostructures of the 2D ferroelectric In₂Se₃ and TM-doped graphene, with the TM coordinated in different ways. We found that (1) having the In₂Se₃enhances the CO2RR activity of the TM-doped graphene and (2) switching the polarization of the In₂Se₃ layer alters the adsorption properties of the intermediates. The beneficial nature of the switchability of the ferroelectric materials provides us with a promising way to control the surface properties, which leads to further control of the desired products in this challenging reaction.