The MgAl2O4 spinel is widely used as the supporting materials for transition metal catalysts due to its unique capability against sintering of metal nanoparticles. The effects of oxygen partial pressure and the Al environment on the surface stability are studied. It is found that the 100_AlO2 termination is the most stable surface structure under the ultra-high vacuum condition at T=1100 K, while the 111_O2(Al) termination becomes the most stable surface in the Al-rich environment as the oxygen pressure increases. The oxygen vacancy formation is thermodynamically favorable over five surface terminations of (100) and (111) orientations. Using Wulff construction with calculated surface Gibbs free energies for both perfect and defective surface terminations, the 100_AlO2 and 111_O2(Al) are found to be the most dominant surface structures under atmospheric condition. The theoretical predictions of this work are consistent with our previously experimental observation.

Computational study on the surface stability of spinel MgAl2O4 materials

252nd National Meeting (2016)

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