Why the breaking of the OOH versus OH scaling relation might cause decreased electrocatalytic activity

In the last decade, tremendous efforts have been dedicated to the breaking of the OOH versus OH scaling relation, which is recognized as the bottleneck for electrocatalysts in the oxygen evolution reaction (OER), the anodic process in water electrolyzers. Breaking the OER scaling relation is seen as a universal remedy to enhance electrocatalytic activity, yet no major progress has so far been achieved in the design of improved OER materials according to this strategy. Introducing kinetics into the thermodynamics-based concept of scaling relations illustrates that the breaking of the OER scaling relation could be accompanied by decreased electrocatalytic activity. As a consequence, it appears imperative to progress the theoretical description of the OER in different directions other than the breaking of this scaling relation. This could include the investigation of competing mechanistic pathways, concerted and decoupled proton-electron transfer steps, or microkinetic considerations in conjunction with machine-learning approaches.