Electrocatalytic and Photocatalytic Reduction of Carbon Dioxide to Carbon Monoxide using the Alkynyl-Substituted Rhenium(I) Complex (5,5´-bisphenylethynyl-2,2´-bipyridyl)Re(CO)3Cl
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The rhenium complex fac-(5,5?-bisphenylethynyl-2,2?-bipyridyl)Re(CO)3Cl was used as a novel catalyst for the electro- and photochemical reduction of CO2 to CO in homogeneous solution. The results were compared to (2,2?-bipyridyl)Re(CO)3Cl as a benchmark compound. Cyclic voltammetric studies as well as bulk controlled potential electrolysis experiments were performed using a CO2 saturated solution in acetonitrile. (5,5?-bisphenylethynyl-2,2?-bipyridyl)Re(CO)3Cl showed a 6.5-fold increase in current density under CO2 at ?1750 mV versus normal hydrogen electrode (NHE) as compared to the operation without CO2. Quantitative analysis by gas chromatography (GC) and infrared spectroscopy showed a Faradaic efficiency of around 45% for the formation of CO.