DFT Study on CO Catalytic Oxidation Mechanism on the Defective Cu2O(111) Surface

• Published in: Journal of physical chemistry. C 2018-07, Vol.122 (29), p.16733-16740
• Main Authors: Wu, Ling-Nan, Tian, Zhen-Yu, Qin, Wu
• Format: Article
• Language: English
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.8b03471

Understanding the role of surface defects on the catalyst performance is of great significance for a good command of the catalytic mechanism on the real catalyst surface. This work reports the mechanistic study of CO oxidation on the defective Cu2O­(111) surface using density functional theory calculations. The effect of surface defects on surface catalytic activity was investigated by creating surface-adsorbed O atoms and Cu vacancies on the perfect Cu2O­(111) surface. Possible defective surface structures were found, and calculated results showed that Cu vacancy on the Cu2O­(111) surface could promote CO oxidation in two ways by (I) promoting the reaction between CO and lattice O with the energy barrier of 1.316 eV following the Mars–van–Krevelen mechanism; (II) promoting the reaction between CO and adsorbed O atoms below 575 K. For the perfect Cu2O­(111) surface, adding adsorbed O to the surface could either cause a strong surface reconstruction with the adsorbed O evolving into a lattice O or stay in the active state. The obtained results could explain the experimental observations that a higher O/Cu ratio on the Cu2O surface can improve the activity of Cu2O toward CO oxidation. Rate constants were provided according to harmonic transition state theory, which would be helpful for the kinetic modeling of CO catalytic oxidation on the real Cu2O surface.