Iron Sulphur Cluster [Fe4S4(SPh)4]^2– Catalyzed Electrochemical Reduction of CO2 on Carbon Electrodes in [Bu4N][BF4]-DMF Mixture

Background: An efficient, selective and durable electrocatalytic carbon dioxide (CO2) reduction system is a prerequisite to tackle energy and pollution-related issues. In this context, both organic and inorganic materials have gained a significant interest worldwide. Objective: In the present work, the electrocatalytic reduction activity of an iron-sulphur (Fe-S) cluster, [Fe4S4(SPh)4]2– for CO2 → carbon monoxide (CO) conversion has been investigated. The effect of catalyst concentration on the yield of CO and H2 was determined. Besides, the influence of reaction conditions (presence or absence of a Brønsted acid, electrolysis time etc.) on faradaic yield and product selectivity was also investigated. Methods: Cyclic voltammetry (CV) was carried out on vitreous carbon electrode in 0.1 M [Bu4N] [BF4]-DMF electrolyte. At the end of electrolysis, products were collected by tight-gas syringe and analyzed by gas chromatography (GC) system coupled with a thermal conductivity detector. Results: The Fe-S cluster was found to efficiently catalyse the process on carbon electrode in 0.1 M [Bu4N][BF4]-DMF electrolyte. Moreover, the presence of cluster shifted the reduction potential by ~ 200 mV towards the positive. GC analysis confirmed the formation of CO with a current efficiency of ca. 70%. On the other hand, 12% H2 was observed at the end of electrocatalysis. Conclusion: In summary, Fe-S cluster was used for the electrocatalytic reduction of CO2 in 0.1 M [Bu4N][BF4]-DMF electrolyte. The use of cluster (catalyst) was found to be important for CO2 reduction as no CO was detected in the absence of the catalyst. This study highlights the potential application of Fe-S cluster for CO2 reduction.