Strain Effects\non the Adsorption of Water on Cerium\nDioxide Surfaces and Nanoparticles: A Modeling Outlook

Nanocrystalline ceria exhibits significant redox activity\nand oxygen\nstorage capacity. Any factor affecting its morphology can tune such\nactivities. Strain is a promising method for controlling particle\nmorphology, whether as core@shell structures, supported nanoparticles,\nor nanograins in nanocrystalline ceria. A key challenge is to define\nroutes of controlling strain to enhance the expression of more active\nmorphologies and to maintain their shape during the lifespan of the\nparticle. Here, we demonstrate a computational route to gain insights\ninto the strain effects on particle morphology. We use density functional\ntheory to predict surface composition and particle morphology of strained\nceria surfaces, as a function of environmental conditions of temperature\nand partial pressure of water. We find that adsorbed molecular water\nis not sufficient to shift stability and as such under all compressive\nand tensile strains studied, the most stable particle is of octahedral\nshape, similarly to the unstrained case. When dissociative water is\ninvolved at the surfaces of the particle, then the most stable particle\nmorphology changes under high water coverage and tensile strain to\ncuboidal or truncated cuboidal shapes. This shift in shape is due\nto strain effects that affect the strength of water adsorption.