Binding and stability of MgO monomers on anatase TiO2(101)

In catalysis, MgO is often used to modify the acid-base properties of support oxides and to stabilize supported metal atoms and particles on oxides. In this study, we show how the sublimation of MgO powder can be used to deposit MgO monomers, hither on anatase TiO2(101). A combination of x-ray electron spectroscopy, high-resolution scanning tunneling microscopy, and density functional theory is employed to gain insight into the MgO monomer binding, electronic and vibrational properties, and thermal stability. In the most stable configuration, the Mg and O of the MgO monomer bind to two surface oxygens and one undercoordinated surface titanium, respectively. The additional binding weakens the Mg-O monomer bond and makes Mg more ionic. The monomers are thermally stable up to 600 K, where the onset of diffusion into the TiO2 bulk is observed. The monomeric MgO species on TiO2(101) represent an ideal atomically precise system with modified acid-base properties and will be employed in our future catalytic studies.

Automated summary

The study demonstrates a method to deposit MgO monomers on the TiO2(101) surface through the sublimation of MgO powder, and employs a combination of techniques to investigate properties such as monomer binding, electronic and vibrational properties, and thermal stability. The most stable configuration involves binding of MgO monomer to surface oxygens and undercoordinated surface titanium, weakening the bond and enhancing thermal stability up to 600 K before diffusion occurs. These monomeric MgO species on TiO2(101) represent an ideal atomically precise system with modified acid-base properties for future catalytic studies.