Descriptor of Non-Local Effects in Oxidative Surface Bonding in Metal-Oxides

The catalytic properties of transition metal oxides (TMOs) are largely defined by their surface bonding. However, an accurate description of adsorption in these systems remains elusive. In this study, we focus on the descriptors of catalytic activity oxygen evolution and reduction reactions using Integrated Crystal Orbital Hamiltonian Population (ICOHP), which was found to be a good descriptor recently.1,2 We use bond-decomposed analysis and expansion beyond the active site to propose an improved ICOHP descriptor which now includes non-local effects of adsorption. This approach is very effective for all systems including previously excluded d0-cases. The size extrapolated change in ICOHP leads to strong linear correlation which is close to unity for 4d and 5d and half of that for 3d. We assign this difference due to adsorption-induced changes in magnetic moments. We argue that non-bonding characteristic of 3d high-spin metals cannot be captured by ICOHP alone and propose tentative solution by adding contributions from crystal field energies. Overall, the size extrapolated approach to ICOHP descriptor not only improves the overall prediction accuracy but also highlights the importance of considering both local and more extended bonding environments in catalytic design of pure oxides and mixed oxides.