The bioinspired [2Fe-2S] butterfly cluster with various dithiolate bridgeheads has been a popular scaffold for study of the hydrogen evolution reaction due to some examples of fast rates, low overpotentials, and relative ease of synthetic tunability. Unfortunately, the details of how the dithiolate bridgehead ligands mechanistically and kinetically affect electrocatalytic generation of H<sub>2</sub> is still not fully understood, especially for reaction with weak acids. We have utilized standard electrochemical measurements alongside IR spectroelectrochemistry and DFT calculations to characterize key catalytic intermediates of a series of alkyl, aryl bridged, and “open” [2Fe-2S] active sites. Using a custom-made, glassy carbon electrode IR spectroelectrochemistry cell, we have observed (in situ) the doubly reduced, singly protonated rate-determining catalytic intermediates of these species that have previously been difficult to isolate and observe. These observations have allowed us to specifically characterize the nature of the first protonation event following reduction of these complexes and to illustrate how the nature of the bridgehead affects their mechanism for HER electrocatalysis.

Mechanisms of variably functionalized [2Fe-2S] electrocatalysts for the hydrogen evolution reaction

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.