Revisiting Oxygen Evolution Reaction: The Role of Competing Pathways and Mechanistic Competition

Oxygen evolution reaction (OER) activity is commonly described using scaling relations and volcano plots derived from a single mechanistic pathway. However, recent theoretical studies show that multiple pathways can coexist and compete, leading to deviations from conventional activity trends. In this review, OER is analyzed as a multi-mechanistic process using the potential-dependent descriptor and the degree of span control (DSC), which together capture the contribution of multiple pathways and elementary steps. Within this framework, scaling relations and volcano plots are reinterpreted as reduced representations of a complex mechanistic landscape. This unified perspective provides a consistent description of OER activity beyond single-mechanism models.