Zn-doping and oxygen vacancy effects on the reactivity and properties of monoclinic and tetragonal ZrO₂: a DFT study

Zirconia oxide (ZrO₂) is a material that has aroused great interest in the scientific community for its general use in various technological applications, such as fuel cells, solar cells, electronic devices, catalysis, dental biomaterial and ceramics. When it is applied as a catalyst, the doping and vacancy effects of their crystalline phases are important properties to guide new developments. This work investigates tetragonal and monoclinic crystalline phases of the Zn-doped ZrO₂ by periodic density functional calculations. Changes in the electronic and acid-basic properties were performed by Bader charge analysis, the density of states calculations (DOS) and the projected density of states (PDOS). The formation of oxygen vacancies was also evaluated. The calculated oxygen vacancy formation energies indicate that it is much easier to generate oxygen vacancy in the Zn-doped ZrO₂ than in the pure material; in addition, oxygen vacancy formation is favored in the monoclinic phase. Bader charge analyses and projected density of states indicated that the doping of ZrO₂ with Zn creates more basic and acid sites. The most stable material is the Zn-doped 3-fold coordinated Zr atom of the m-ZrO₂, which can be used for future developments and applications.