CO₂ Activation and Dissociation on Exsolved Ni/La₂O₃ Catalysts: A First-Principles Study

In this study, we performed spin-polarized periodic density functional theory (DFT) calculations to understand the electronic structure and catalytic activity of exsolved Ni nanoparticles supported on La2O3 (i.e., Ni/La2O3) as reported in the recent experimental literature. We used simple slab models to study the electronic structure and reactivity of the Ni/La2O3 overlayer surfaces. The modifications in the electronic and geometric properties of Ni/La2O3 as successive layers of Ni are added on top of La2O3 are systematically investigated by using the d-band model as well as by studying the adsorption and dissociation of CO2. We examined the interaction of CO2 on the surface of Ni/La2O3 by computing adsorption energetics, optimized geometries, charge transfer, and density of states. As the interaction between CO2 and the Ni surface is weak, we employed van der Waal corrections in our calculations. Our results suggest that the adsorption of CO2 is more favorable on the Ni/La2O3 surface compared to that on the simple Ni(111) surface. Furthermore, we have also found that the activation barrier for CO2 dissociation increases with an increase in the number of Ni layers from one layer to three and that the energy of the reaction becomes less exothermic. This shows that the dissociation of CO2 becomes both kinetically and thermodynamically less favorable as we increase the number of Ni layers over La2O3. Thus, a single monolayer of Ni/La2O3 is the most active among the surfaces investigated here for the adsorption and dissociation of CO2. We show how this is due to the synergistic effect of geometric and electronic factors. The energetics of the CO2 dissociation reaction follow a Bro̷nsted–Evans–Polanyi relationship where the activation energy is linearly correlated to the reaction energy for all the surfaces studied here. The present study’s findings offer valuable perspectives on the correlation between the electronic configuration and catalytic capabilities of Ni/La2O3 catalysts. Consequently, these insights are expected to be useful in the design of novel, high-performance, supported metal catalysts for a range of important reactions.