Catalysis is a life-changing process that plays a pivotal role in the production of medicines, fuels and materials. The development of low cost and efficient catalysts for hydrogen production from renewable sources is essential for storing energy to overcome the problems faced by high energy demands in residential and industrial sectors. To replace expensive and rare precious metals in electrolyzers, there is a need to develop Earth-abundant transition metal electrocatalysts that rival the activity, robustness, and efficiency of precious metals. Inspired by the structure-function relationships within the naturally occurring [Fe-Fe] Hydrogenase enzyme, we present new iron electrocatalysts that contain a cyclopentadienyl (Cp) ligand with multiple amine functionalities for managing proton and electron movement on a molecular level. Through mechanistic studies, we observed that by selectively removing the CO ligand prior to electrocatalysis, there is a significant increase in the rate of H2 production in the presence of an exogeneous acid. Computational studies reveal that the direct endo-Cp ring protonation is most favorable after 1e- reduction and amines only behave as ancillary electron-rich functionalities, contrary to the fact that amines in the second coordination sphere are often protonated in the electrocatalysis. With the help of experimental and computational data, a novel alternative pathway for H2 production is proposed. Future work is aimed at understanding the mechanism of H2 production and modifying the amine functionalized moiety to increase the catalytic activity and efficiency of this new family of Earth-abundant electrocatalysts.

Amine rich iron electrocatalysts in H2 production

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