Dissociation of liquid water on defective rutile TiO 2 (110) surfaces using ab initio molecular dynamics simulations

• Published in: Frontiers of physics 2018, Vol.13 (3), p.138107
• Main Authors: Wang (王会丽), Hui-Li, Hu (胡振芃), Zhen-Peng, Li (李晖), Hui
• Format: Article
• Language: English
• Subjects: ab initio molecular dynamics; exothermic reaction; free energy barrier; rutile; spontaneous reaction
• ISSN: 2095-0462; 2095-0470
• DOI: 10.1007/s11467-018-0763-5

In order to obtain a comprehensive understanding of both thermodynamics and kinetics of water dissociation on TiO 2, the reactions between liquid water and perfect and defective rutile TiO 2 (110) surfaces were investigated using ab initio molecular dynamics simulations. The results showed that the free-energy barrier (~4.4 kcal/mol) is too high for a spontaneous dissociation of water on the perfect rutile (110) surface at a low temperature. The most stable oxygen vacancy (V o1) on the rutile (110) surface cannot promote the dissociation of water, while other unstable oxygen vacancies can significantly enhance the water dissociation rate. This is opposite to the general understanding that V o1 defects are active sites for water dissociation. Furthermore, we reveal that water dissociation is an exothermic reaction, which demonstrates that the dissociated state of the adsorbed water is thermodynamically favorable for both perfect and defective rutile (110) surfaces. The dissociation adsorption of water can also increase the hydrophilicity of TiO 2.