The bifunctional volcano plot: thermodynamic limits for single-atom catalysts for oxygen reduction and evolution

Single-atom catalysts (SACs) are a promising route to create highly-efficient bifunctional catalysts for O-2 reduction and evolution. Here, we show how adsorption-energy scaling relations can be used to build a Sabatier-type bifunctional volcano plot. The plot helps establish thermodynamic limits to bifunctional SACs and suggests that high bifunctional activities are more easily reached by SACs containing several different species.