Hydration of Calcium Oxide Surface Predicted by Reactive Force Field Molecular Dynamics

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• 作者：Hegoi Manzano ; Roland J. M. Pellenq ; Franz-Josef Ulm ; Markus J Buehler ; Adri C. T. van Duin
• 刊名：Langmuir
• 出版年：2012
• 出版时间：March 6, 2012
• 年：2012
• 卷：28
• 期：9
• 页码：4187-4197
• 全文大小：596K
• 年卷期：v.28,no.9(March 6, 2012)
• ISSN：1520-5827

文摘

In this work, we present the parametrization of Ca鈥揙/H interactions within the reactive force field ReaxFF, and its application to study the hydration of calcium oxide surface. The force field has been fitted using density functional theory calculations on gas phase calcium鈥搘ater clusters, calcium oxide bulk and surface properties, calcium hydroxide, bcc and fcc Ca, and proton transfer reactions in the presence of calcium. Then, the reactive force field has been used to study the hydration of the calcium oxide {001} surface with different water contents. Calcium oxide is used as a catalyzer in many applications such as CO₂ sequestration and biodiesel production, and the degree of surface hydroxylation is a key factor in its catalytic performance. The results show that the water dissociates very fast on CaO {001} bare surfaces without any defect or vacancy. The surface structure is maintained up to a certain amount of water, after which the surface undergoes a structural rearrangement, becoming a disordered calcium hydroxyl layer. This transformation is the most probable reason for the CaO catalytic activity decrease.