First-Principles Design of Iron-Based Active Catalysts for Adsorption and Dehydrogenation of H2O Molecule on Fe(111), W@Fe(111), and W2@Fe(111) Surfaces

• Published in: Journal of physical chemistry. C 2016-11, Vol.120 (45), p.25780-25788
• Main Authors: Hsiao, Ming-Kai, Hsieh, Yi-Chun, Chen, Hui-Lung
• Format: Article
• Language: English
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.6b07455

The adsorption and dehydrogenation of water on Fe(111), W@Fe(111), and W2@Fe­(111) surfaces have been studied via employing the first-principles calculations method based on the density functional theory. The three adsorption sites of the aforesaid surfaces, such as top (T), 3-fold-shallow (S), and 3-fold-deep (D), were considered. The most favorable structure of all OH x (x = 0–2) species on the surfaces of Fe(111), W@Fe(111), and W2@Fe­(111) have been thoroughly predicted and discussed. Our calculated results revealed that the adsorbed configurations of FeH2O­(T-η1-O)-b, W@FeH2O­(T-η1-O)-a, and W2@FeH2O­(T-η1-O)-a possess energetically the most stable structure with their corresponding adsorption energies of −8.08, −13.37, and −18.61 kcal/mol, respectively. In addition, the calculated activation energies for the first dehydrogenation processes (HO-H bond scission) of H2O on Fe(111), W@Fe(111), and W2@Fe­(111) surfaces are 24.40, 12.62, and 9.97 kcal/mol, respectively. For second dehydrogenation processes (O–H bond scission), the corresponding activation energies of OH on Fe(111), W@Fe(111), and W2@Fe­(111) surfaces are 39.35, 22.69, and 26.24 kcal/mol, respectively. Finally, the entire dehydrogenation courses on the varied Fe(111), W@Fe(111), and W2@Fe­(111) surfaces are exothermic by 20.08, 41.35, and 59.30 kcal/mol, respectively. To comprehend the electronic properties of its nature of interaction between the adsorbate and substrate, we calculated the electron localization functions, local density of states, and Bader charges; the results were consistent and explicable.