Mainstream and Sidestream Modeling in Oxygen Evolution Electrocatalysis

The oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are key in numerous electrochemical technologies, such as water electrolyzers, CO₂ electrolyzers, low-temperature fuel cells, regenerative fuel cells and some metal-air batteries. The OER and ORR tend to be sluggish and catalyzed by scarce and expensive materials, the durability of which is often insufficient. For two decades, computational methods have been regarded as a cost-effective means to explain experimental observations, test hypothesis, and design new materials for these two reactions.

Currently, the most widely used computational model is based on the free energies of the intermediates (*O, *OH, *OOH) and the scaling relations among them. Since the publication of two seminal papers in 2011, the scaling relation between the adsorption energies of *OOH and *OH was assigned all the responsibility for the experimental inefficiencies of OER and ORR electrocatalysts. This triggered a research paradigm based on breaking such scaling relation that still lasts until this day (see the diagram next to this text). After noting in 2018 that breaking the scaling relation between *OOH and *OH does not necessarily entail an improvement of the OER overpotential, my group moved away from the mainstream and has since been devising alternative descriptors and methods to enhance OER electrocatalysts and bifunctional OER/ORR electrocatalysts.

In this Account, I will describe when and why we introduced the concepts of electrochemical symmetry, delta-epsilon optimization, bifunctional volcano plot, and error awareness, among others, aiming to provide quantitative tools for the computational design and optimization of electrocatalysts.