Activity volcanoes for the electrocatalysis of homolytic and heterolytic hydrogen evolution

This paper derives a simple kinetic model for the electrochemical current generated by a heterolytic model for hydrogen evolution, as it would apply to the reaction taking place on molecular catalysts, and compares the activity trends to the classical Volmer-Heyrovsky-Tafel models. It is demonstrated that in the heterolytic mechanism, pH plays a crucial role in optimizing the overall activity.