Water electrolyzers for green H₂ production may be massively used if suitable catalysts for O₂ evolution are found. Alas, adsorption-energy scaling relations have led to uncertain catalyst design heuristics. Here, high-throughput scaling-free and scaling-based optimizations are performed while tracking electrochemical symmetry. O₂ evolution activity enhancement is linked to an increase in the number of electrochemical steps above 1.23 eV.

The global-scale use of water electrolyzers for sustainable hydrogen production is currently limited by the lack of efficient, abundant, and stable catalysts for the oxygen evolution reaction (OER). Unfortunately, OER models based on adsorption energies of the intermediates and their scaling relations have led to the customary but unsafe use of heuristic rules as design principles for catalyst design. Conversely, guidelines derived from the concept of electrochemical symmetry have yet to be exploited despite their simplicity and quantitative nature. Here, a high-throughput analysis on a sizable dataset is performed using a variety of scaling-free, scaling-based optimizations, and combinations thereof, while keeping track of the material's degree of electrochemical symmetry. This analysis provides an important conclusion: a visible improvement in the OER activity is statistically linked to an increase in the number of electrochemical steps larger than 1.23 eV. This is not a mere rule of thumb but a quantitative criterion to safely guide the design and enhancement of OER catalyst materials.