The computational setup is very similar to the one described previously. In short, spinpolarized periodic DFT calculations were performed utilizing the Vienna ab initio software package (VASP), with ionic cores described by the projected augmented wave (PAW) method. The Perdew-Burke-Ernzerhof (PBE) functional was used for exchangecorrelation energies within the generalized gradient approximation (GGA). The cut-off energy of the plane wave basis in the expansion of the wave functions was set to be 600 eV. On-site Coulomb interactions were considered using the DFT+U approach to treat the highly localized 4d states of Zr. The parameter U-J = 4.00 eV was taken from a previous work. Dispersion corrections were included within the DFT-D3 method. The k-point mesh was set to be 3  3  1 for the slab calculations, due to the negligible energy variation obtained for 5  5  1 and 3  3  1 meshes for the (1  3) super cell of ZrO2(111). A k-point mesh of 9  9  9 was utilized to optimize the bulk structure of the ZrO2 support. Here we used the monoclinic -phase, which is the most stable phase at room temperature. Ionic bulk relaxations were considered to reach convergence for forces below 0.001 eV/Å. We employed the charge partitioning method reported by Manz et al. to calculate local charges. This method is wellsuited for strongly polarized systems. However, we also tested this approach against alternative charge partition schemes, which resulted in consistent trends regarding alterations and disparities in the charge states.