CO₂ Activation on Ni/γ–Al₂O₃ Catalysts by First-Principles Calculations: From Ideal Surfaces to Supported Nanoparticles

Due to the impact of anthropogenic CO₂ emissions on global warming, the conversion of this molecule to useful products is of increasing interest. Therefore, further understanding of the CO₂ activation is needed. Ni-based catalysts are able to dissociate and convert CO₂ into fuels, and although these systems are generally simulated using simple slab models, real catalysts are significantly more complex. They are generally composed of nanoparticles supported on oxides, being γ-Al₂O₃ one of the most widely used supports. In this study, we perform ab initio simulations in order to model the CO₂ activation on Ni nanoparticles supported on γ-Al₂O₃. Starting from ideal surface terminations, going to Ni nanoparticles (0.5–1 nm) and up to γ-Al₂O₃ supported Ni nanoparticles, the role of terraces, steps, edges, and the support is evaluated for this chemical transformation. The metal–oxide interface provides the most active sites for CO₂ activation, due to a synergistic effect between the nickel nanoparticles and the Lewis acidic sites of γ-Al₂O₃.