(521dx) Exploring Activity Descriptors in Electrocatalysis of Transition Metal-Oxides Using Computational Tools

Currently, the most effective electrocatalysts for oxygen reduction (ORR) and oxygen evolution reactions (OER) are comprised of noble metal oxides, which bring issues of high cost and scarcity. Discovering earth-abundant alternatives is challenging due to the costly and time-consuming experiments. High-throughput atomistic simulation of catalysts can be an efficient route for enabling the better design and discovery of new electrocatalysts. The effectiveness of this approach depends on the presence of an activity descriptor that can accurately capture both qualitative and quantitative catalytic trends. In the past, multiple descriptors based on electronic properties have been proposed for reaction-specific or system-specific applications. Therefore, we need a descriptor, which can capture the bonding strength accurately for any sort of reaction or system.

In this study, we are examining the relationship between adsorption energy and integrated COHP (ICOHP) values of a series of polymorphs in all conceivable oxidation states, ranging from +2 to +6, respectively. We have observed a strong correlation between the integrated COHP (ICOHP) of the bulk system and the adsorption energy, which indicates expensive surface-level electronic calculations can be replaced by bulk-level computations. However, this correlation does not hold on two classes of systems: (i) d⁰ systems and (ii) systems with significant surface distortion during the reaction. To address these systems, we have considered a different approach where we consider the sum of ICOHP values around the active site, and then expand the sum rule to include neighboring and next neighboring centers, rather than relying solely on a single bond ICOHP value.