Toward the rational benchmarking of homogeneous H2-evolving catalysts

Molecular electrocatalysts for H-2 evolution are usually studied under various conditions (solvent and proton sources) that prevent direct comparison of their performances. We provide here a rational method for such a benchmark based on (i) the recent analysis of the current-potential response for two-electron-two-step mechanisms and (ii) the derivation of catalytic Tafel plots reflecting the interdependency of turnover frequency and overpotential based on the intrinsic properties of the catalyst, independent of contingent factors such as cell characteristics. Such a methodology is exemplified on a series of molecular catalysts among the most efficient in the recent literature.