Effects of Nanosizing of Zirconia and Bandstructure Modulation on Catalytic Activity: Insights from a Combined Density Functional Tight Binding – Order(N) Density Functional Theory Study

Zirconia based materials are widely utilized in the electrodes of solid oxide fuel cells and electrolysis cells. Interactions of small molecules with zirconia surfaces are of key importance in these applications. Numerous theoretical reports have focused on periodic models, while the properties of materials at the nanoparticle or cluster scales may differ markedly from their bulk counterparts. However, ab initio level understanding of gas adsorption behavior on Zirconia at this scale remains limited. We will present a comparative analysis based on first principles and semiempirical calculations of cubic ZrO₂ nanoparticles, varying in size from a few tens to a thousand atoms. This is achieved by combining density functional-based tight-binding (DFTB) and order-N DFT to balance computational cost and increase scalability. The band structure of the nanoparticles, which proves sensitive to oxygen deficiencies, exerts a significant influence on gas adsorption behavior. Notably, nanoparticles can exhibit intrinsic as well as p- and n-doped characteristics corresponding to O-rich or O-poor conditions. The n-type particles display heightened reactivity for the adsorption of CO and CO₂ gases on their surfaces with promoted electron transfer from zirconia adsorbents to the adsorbed molecules, which is useful for their catalysis, with the effect stronger due to nanosizing. Our results suggest good potential of nanosizing and bandstructure engineering in zirconia nanoparticles to achieve enhanced gas adsorption and catalytic performance, thus presenting promising utilization prospects in energy devices.