Find in Library
Search millions of books, articles, and more
Indexed Open Access Databases
Co and Ni Incorporated γ-Al<sub>2</sub>O<sub>3</sub> (110) Surface: A Density Functional Theory Study
oleh: Huaxi Li, Liu Shi, Chengkai Jin, Runping Ye, Rongbin Zhang
Format: | Article |
---|---|
Diterbitkan: | MDPI AG 2022-01-01 |
Deskripsi
Investigation into the state and mechanisms of the active metal substitution into the γ-Al<sub>2</sub>O<sub>3</sub> support is the basis for design of many catalysts. Periodic density functional theory (DFT) +U calculations were used to investigate the surface properties of transition metals Co<sup>3+</sup> and Ni<sup>3+</sup> cations substitute for the Al<sup>3+</sup> cations of γ-Al<sub>2</sub>O<sub>3</sub> (110) surface. It was found that the substitution energy of one Al<sup>3+</sup> substituted by Co<sup>3+</sup> and Ni<sup>3+</sup> are −61 and −57 kJ/mol, respectively. The Co and Ni preferentially substitute the tetrahedral Al sites instead of the octahedral Al sites. Using thermodynamics, the Al atoms in the top layer of γ-Al<sub>2</sub>O<sub>3</sub> (110) can be 100% substituted by Co and Ni. Ni is easier to substitute the Al atom than Co. There is no obvious structural distortion that occurs after Co and Ni substituted all the top layer Al atoms. While the band gaps of the substituted surface become narrower, resulting in the increase of surface Lewis acidity. In addition, the oxygen vacancy formation energies of the Co and Ni substituted surface are 268 and 53 kJ/mol, respectively. The results provide interface structure and physical chemistry properties of metal-doped catalysts.