Inverse potential scaling in co-electrocatalytic activity for CO reduction through redox mediator tuning and catalyst design

Electrocatalytic CO 2 reduction is an attractive strategy to mitigate the continuous rise in atmospheric CO 2 concentrations and generate value-added chemical products. A possible strategy to increase the activity of molecular systems for these reactions is the co-catalytic use of redox mediators (R...

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Veröffentlicht in:Chemical science (Cambridge) 2022-08, Vol.13 (33), p.9595-966
Hauptverfasser: Reid, Amelia G, Moreno, Juan J, Hooe, Shelby L, Baugh, Kira R, Thomas, Isobel H, Dickie, Diane A, Machan, Charles W
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Zusammenfassung:Electrocatalytic CO 2 reduction is an attractive strategy to mitigate the continuous rise in atmospheric CO 2 concentrations and generate value-added chemical products. A possible strategy to increase the activity of molecular systems for these reactions is the co-catalytic use of redox mediators (RMs), which direct reducing equivalents from the electrode surface to the active site. Recently, we demonstrated that a sulfone-based RM could trigger co-electrocatalytic CO 2 reduction via an inner-sphere mechanism under aprotic conditions. Here, we provide support for inner-sphere cooperativity under protic conditions by synthetically modulating the mediator to increase activity at lower overpotentials (inverse potential scaling). Furthermore, we show that both the intrinsic and co-catalytic performance of the Cr-centered catalyst can be enhanced by ligand design. By tuning both the Cr-centered catalyst and RM appropriately, an optimized co-electrocatalytic system with quantitative selectivity for CO at an overpotential ( η ) of 280 mV and turnover frequency (TOF) of 194 s −1 is obtained, representing a three-fold increase in co-catalytic activity at 130 mV lower overpotential than our original report. Importantly, this work lays the foundation of a powerful tool for developing co-catalytic systems for homogeneous electrochemical reactions. The use of sulfone-based redox mediators in electrocatalytic CO 2 reduction by Cr-centered complexes enhances the turnover frequencies at lower overpotentials via inner-sphere electron transfer and pancake bonding.
ISSN:2041-6520
2041-6539
DOI:10.1039/d2sc03258a