Impactful Role of Cocatalysts on Molecular Electrocatalytic Hydrogen Production
Charles G. Margarit, Naomi G. Asimow, Agnes E. Thorarinsdottir, Cyrille Costentin, Daniel G. Nocera
Abstract
Hydrogen evolution from a weak acid, acetic acid, occurs at extremely high rates for iron tetraphenylporphyrin in the presence tertiary amine as a cocatalyst. Kinetic analysis of H2 evolution for a range of amines with varying coordinative and acid–base properties reveals a dramatic rate enhancement derived from enhanced proton activity of a heteroconjugated adduct between acetic acid and the amine. Additionally, nonbulky tertiary amines (quinuclidine and diazabicyclooctane) result in a further increase in activity resulting from a trans effect for a TPPFe(II)–H hydride intermediate. These findings reveal the design principle of a cocatalyst for creating more efficient molecular systems for hydrogen evolution electrocatalysis.