(378d) Exploring the Oxygen Surface Reactivity on Non-Octahedral Sites in Transition Metal-Oxides

The development of the cost-effective catalyst for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is a key to a sustainable green energy future. Transition metal oxides (TMO) are found to be promising systems due to their high stability under oxidizing conditions. The vast majority of TMO systems are built of octahedral (six-coordinated) M-O building blocks and other non-octahedral coordination such as tetrahedral/square planar (four-coordinated) and trigonal bipyramidal/square pyramidal (five-coordinated) are rarely studied for catalytic applications. In this work, we have carried out a surface reactivity study for TMO with non-octahedral building blocks like wurtzite, tellurite, pentoxide and other crystal classes for the entire 3d, 4d and 5d TMO series. Our recent study [1] on the bonding nature of O*, OH* intermediate on the octahedral sites pointed out two primary contributors behind this adsorption energy: (i) spin-dependent coupling strength of metal-d and oxygen-2p states and (ii) extent of filling of bonding and anti-bonding orbitals. In this project, we have computed and analyzed O*, OH* surface reactivity trends on non-octahedral sites with the most stable surfaces of each system. We have also incorporated crystal orbital Hamiltonian population (COHP) analysis [2] which is a single potential descriptor [1] to identify the reactivity. This study identifies important differences between non-octahedral systems and their octahedral counterparts creating a pathway toward unexplored potential catalytic systems. This research was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division, Catalysis Science Program to the SUNCAT Center for Interface Science and Catalysis.