Molecular electrocatalysis has emerged as a powerful strategy for driving electrochemical transformations, yet non-ideal electrochemical behavior and catalyst deactivation often obscure intrinsic catalytic activity. This article reviews recent advances from our group in understanding and modeling catalyst deactivation, self-moderation, and self-protection phenomena in molecular electrocatalysis. After revisiting a tutorial case of irreversible spontaneous catalyst deactivation, we analyze more complex scenarios where deactivation is induced by reactions with co-substrates, exemplified by proton-driven inhibition during N 2 O reduction mediated by 4-cyanopyridine. We then introduce the concept of self-moderation, in which reaction products or co-products reversibly or irreversibly bind to the catalyst and regulate activity, as illustrated by N 2 O and CO 2 reduction catalyzed by rhenium, iron, and cobalt complexes. Finally, we describe a self-protection mechanism enabling catalysis in the presence of contaminants, demonstrated for CO 2 reduction catalyzed by an iron porphyrin in the presence of O 2 . Throughout, kinetic modeling combined with electrochemical techniques provides quantitative insight into competing catalytic, inhibitory, and mass-transport processes.
Cyrille Costentin (Sun,) studied this question.