Water is one of the most important adsorbates interacting with the diamond surface. In particular, the presence of -H and -OH on the surface affects the physical and chemical properties of nanocrystalline diamond particles, which are promising new materials for biomedical applications. However, the effect of point defects on the chemisorption of water are still poorly understood. In this paper we simulated a dissociative adsorption of a water molecule on the C(100)-(2×1) diamond surface with a vacancy defect. Water adsorption on the C1 atom near the vacancy on the clean surface leads to a metastable state formation in which the molecule remains whole. A further H2O→OH+H dissociation can go in different directions. For each of the cases, we calculated the activation energy of adsorption from the initial system state through and bypassing the metastable state. Perhaps, the atom near the vacancy can be considered as a center of the water molecule “capture” which keeps the water in a molecular form on the surface. Surface covering with the water dissociation fragments leads to an adsorption heat reduction of the -OH and -H groups adsorbed on the defect. The results can be used to analyze the physical and chemical processes on the surface of ultrafine diamonds.
Journal: TechConnect Briefs
Volume: 2, Nanotechnology 2013: Electronics, Devices, Fabrication, MEMS, Fluidics and Computational (Volume 2)
Published: May 12, 2013
Pages: 564 - 567
Industry sector: Advanced Materials & Manufacturing
Topics: Informatics, Modeling & Simulation