Exploring the Adsorption Properties of Small Molecules on CeZr-Based Nanoclusters

Area of Science:

• Surface Science and Catalysis
• Computational Chemistry
• Materials Science

Background:

• Optimizing heterogeneous catalytic performance requires understanding molecule-surface interactions at an atomistic level.
• Ceria, zirconia, and mixed ceria-zirconia nanoclusters are vital components in various catalytic applications.
• Characterizing adsorption modes is essential for predicting and enhancing catalytic activity.

Purpose of the Study:

• To computationally investigate the adsorption behavior of key molecules (CO, CO2, CH4, NH3, H2O, SO2) on ceria, zirconia, and mixed ceria-zirconia nanoclusters.
• To develop and apply an automated algorithm for characterizing adsorption modes, including orientation and site preferences.
• To elucidate the electronic interactions between adsorbed molecules and oxide nanocluster surfaces.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to model molecule-nanocluster interactions.
• An automated algorithm combining Coulomb matrix representations and k-means clustering was developed for adsorption mode analysis.
• Silhouette scores were used to determine the optimal number of representative adsorption structures.

Main Results:

• The 6 nearest substrate atoms effectively represent molecule orientation and site preference on the nanoclusters.
• Adsorbed molecules (CO, CO2, CH4, NH3, H2O, SO2) exhibited distinct, consistent orientation patterns (e.g., parallel, inclined).
• SO2 showed significant bond angle deformation towards SO3 on ceria, acting as an electron acceptor, unlike other molecules which donated electron density.

Conclusions:

• The study successfully characterized diverse adsorption modes on oxide nanoclusters, providing insights into molecule-surface interactions.
• The developed automated algorithm offers an efficient method for analyzing complex adsorption phenomena in catalysis.
• Understanding these interactions is key to designing improved catalysts for heterogeneous reactions.