The interest in electrochemical carbon dioxide (CO2) reduction is two-fold: the association of climate change with the rise in atmospheric CO2 concentrations globally and the increasing need to transition from fossil fuel-derived hydrocarbons as chemical feedstocks and energy sources. The use of the CO2 reduction reaction (CO2RR) can help to mitigate both of these issues through the conversion of CO2 into value-added products/useful building blocks for the synthesis of chemical feedstocks and fuels. Molecular electrocatalysts for the CO2RR have been developed, but there remains a need to improve the activity of these systems. Our group has reported a chromium (Cr)-centered catalyst, Cr(tbudhbpy)Cl(H2O) 1, where 6,6′-di(3,5-di-tert-butyl- 2-phenolate)-2,2′-bipyridine = [tbudhbpy]2-, which is highly selective for carbon monoxide (CO) when phenol is used as a proton source. To improve the activity, dibenzothiophene 5,5-dioxide (DBTD) was employed as a redox mediator (RM) to produce a co-electrocatalytic response with 1 under aprotic and protic conditions. Experimental and computational data suggest that DBTD coordinates to the Cr center trans to the site of CO2 binding stabilized by through-space electronic conjugation between the bpy ligand fragment and DBTD. Experimental data with structural derivatives of both 1 and DBTD support the computationally predicted coordination of DBTD during the catalytic cycle. Additionally, further optimization of the system can be achieved through tuning the stereoelectronic properties of both the catalyst and RM.

Mediated inner-sphere electron transfer induces homogeneous reduction of CO2 via through-space electronic conjugation

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ACS Fall 2022

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