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Molecular and dissociative adsorption of a single water molecule on a β‐dicalcium silicate (100) surface explored by a DFT approach
Author(s) -
Zhang Yue,
Lu Xinying,
He Zhen,
Song Dongsheng
Publication year - 2018
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15381
Subject(s) - adsorption , chemistry , density functional theory , molecule , calcium silicate hydrate , calcium silicate , inorganic chemistry , atom (system on chip) , computational chemistry , materials science , organic chemistry , cement , computer science , metallurgy , composite material , embedded system
The adsorption of water on a C 2 S surface initiates belite to hydrate. In the present work, the adsorption behavior of single water molecule on a β‐C 2 S (100) surface is explored using density functional theory ( DFT ) due to the lack of alternative approaches for direct observation. Four possible calcium atom sites on the β‐C 2 S (100) surface slab are considered in our calculations. The results show that water can adsorb on the 2 five‐coordinated calcium sites only via molecular adsorption with adsorption energies of 0.59 and 0.85 eV, respectively, but can dissociate on the other 2 six‐coordinated calcium sites with higher adsorption energies of 0.96 and 0.99 eV, respectively. The energy barriers to the dissociative adsorption of water at the Ca( III ) site(0.10 eV) is much lower than that at the Ca( IV ) site, indicating that water prefers to adsorb and dissociate on Ca( III ) sites. The dissociative adsorption of water causes more obvious surface calcium shifts and Si–O bond length increases than molecular adsorption. The dissociative adsorption of a water molecule changes the electron distribution, and the overlap between Ca 2 p and O 2 s orbitals leads to new Ca–O bond formations.