A general but still unknown characteristic of active oxygen evolution electrocatalysts

The unsatisfactory electrocatalysis of the oxygen evolution reaction (OER) is a major hurdle for the sustainable production of hydrogen using water electrolyzers. Besides, most state-of-the-art catalysts are based on expensive and scant elements such as Ru and Ir. Hence, it is paramount to establish the features of active OER catalysts to make well-informed searches. Here, an affordable statistical analysis exposes a general yet unnoticed characteristic of active materials for the OER: they frequently have three out of four electrochemical steps with free energies above 1.23 eV. For such catalysts, the first three steps (abbreviated as: H2O -> *OH, *OH -> *O, *O -> *OOH) are statistically prone to be over 1.23 eV, and the second step is often potential limiting. Finally, electrochemical symmetry, a recently introduced concept, is shown to be a simple and convenient criterion for the in silico design of enhanced OER catalysts, as materials with three steps over 1.23 eV tend to be highly symmetric.

Automated summary

A statistical analysis reveals that active oxygen evolution reaction (OER) catalysts often have three electrochemical steps with free energies above 1.23 eV, with the second step being the potential limiting step. Electrochemical symmetry is shown to be a convenient criterion for the design of enhanced OER catalysts.