CO₂ Adsorption and Activation on the (110) Chalcopyrite Surfaces: A Dispersion-Corrected DFT + U Study

We have used the density functional theory within the plane-wave framework to understand the reconstruction of most stable (110) chalcopyrite surfaces. Reconstructions of the polar surfaces are proposed, and three different possible nonpolar terminations for the (110) surface, namely, I, II, and III, are investigated. A detailed discussion on stabilities of all three surface terminations is carried out. It is generally observed that the (110) chalcopyrite surfaces encounter significant reconstruction in which the metal Fe and Cu cations in the first atomic layer considerably move downward to the surface, while the surface S anions migrate slightly outward toward the surface. We also investigated the adsorption of the CO₂ molecule on the three terminations for the (110) surface by exploring various adsorption sites and configurations using density functional theory calculations, in which long-range dispersion interactions are taken into consideration. We show that the CO₂ molecule is adsorbed and activated, while spontaneous dissociation of the CO₂ molecule is also observed on the (110) surfaces. Structural change from a neutral linear molecule to a negatively charged (CO₂ ^-δ) slightly or considerably bent species with stretched C-O bond distances are highlighted for description of the activation of the CO₂ molecule. The results address the potential catalytic activity of the (110) chalcopyrite toward the reduction and conversion of CO₂ to the organic molecule, which is appropriate to the production of liquid fuels.