CO<sub>2</sub> Activation\nand Dissociation on Exsolved\nNi/La<sub>2</sub>O<sub>3</sub> Catalysts: A First-Principles Study

In this study, we performed spin-polarized periodic density\nfunctional\ntheory (DFT) calculations to understand the electronic structure and\ncatalytic activity of exsolved Ni nanoparticles supported on La<sub>2</sub>O<sub>3</sub> (i.e., Ni/La<sub>2</sub>O<sub>3</sub>) as reported\nin the recent experimental literature. We used simple slab models\nto study the electronic structure and reactivity of the Ni/La<sub>2</sub>O<sub>3</sub> overlayer surfaces. The modifications in the\nelectronic and geometric properties of Ni/La<sub>2</sub>O<sub>3</sub> as successive layers of Ni are added on top of La<sub>2</sub>O<sub>3</sub> are systematically investigated by using the <i>d</i>-band model as well as by studying the adsorption and dissociation\nof CO<sub>2</sub>. We examined the interaction of CO<sub>2</sub> on\nthe surface of Ni/La<sub>2</sub>O<sub>3</sub> by computing adsorption\nenergetics, optimized geometries, charge transfer, and density of\nstates. As the interaction between CO<sub>2</sub> and the Ni surface\nis weak, we employed van der Waal corrections in our calculations.\nOur results suggest that the adsorption of CO<sub>2</sub> is more\nfavorable on the Ni/La<sub>2</sub>O<sub>3</sub> surface compared to\nthat on the simple Ni(111) surface. Furthermore, we have also found\nthat the activation barrier for CO<sub>2</sub> dissociation increases\nwith an increase in the number of Ni layers from one layer to three\nand that the energy of the reaction becomes less exothermic. This\nshows that the dissociation of CO<sub>2</sub> becomes both kinetically\nand thermodynamically less favorable as we increase the number of\nNi layers over La<sub>2</sub>O<sub>3</sub>. Thus, a single monolayer\nof Ni/La<sub>2</sub>O<sub>3</sub> is the most active among the surfaces\ninvestigated here for the adsorption and dissociation of CO<sub>2</sub>. We show how this is due to the synergistic effect of geometric\nand electronic factors. The energetics of the CO<sub>2</sub> dissociation\nreaction follow a Bro̷nsted–Evans–Polanyi relationship\nwhere the activation energy is linearly correlated to the reaction\nenergy for all the surfaces studied here. The present study’s\nfindings offer valuable perspectives on the correlation between the\nelectronic configuration and catalytic capabilities of Ni/La<sub>2</sub>O<sub>3</sub> catalysts. Consequently, these insights are expected\nto be useful in the design of novel, high-performance, supported metal\ncatalysts for a range of important reactions.