Effect of strain on the adsorption of carboxylic acids on the surfaces of cerium oxide

Cerium oxide nanoparticles are versatile materials suitable for a wide range of catalytic and biotechnological applications. Controlling morphology and surface characteristics is crucial for enhancing their activity, but they are affected by a complex interplay of temperature and partial pressures of oxygen and any adsorbates involved. Here, we use first-principles calculations alongside a thermodynamic approach to model how carboxylic acids, like formic, carbonic, acetic, glycolic, glyoxylic, and oxalic acids, interact with the stoichiometric and oxygen-deficient strained and unstrained {100}, {110}, and {111} cerium oxide surfaces, and how environmental conditions affect the morphology and surface characteristics of ceria nanoparticles. Our analysis includes monodentate, bidentate, and chelate adsorption for each acid, with bidentate adsorption typically showing the highest stability. The presence of oxygen vacancies enhances the adsorption compared to stoichiometric surfaces. We found that adsorbed carboxylic acids can access different particle morphologies under oxidizing conditions. However, in reduced conditions, octahedral shapes dominated by {111} facets tend to be more stable. Hence, our data may exclude thermodynamics as the predominant factor affecting morphology in the presence of carboxylic acids, inferring that kinetic factors affect the growth of ceria nanoparticles.