Electrocatalytic Reduction of Carbon Dioxide to Carbon Monoxide by a Polymerized Film of an Alkynyl‐Substituted Rhenium(I) Complex

The alkynyl‐substituted Re I complex [Re(5,5′‐bisphenylethynyl‐2,2′‐bipyridyl)(CO) 3 Cl] was immobilized by electropolymerization onto a Pt‐plate electrode. The polymerized film exhibited electrocatalytic activity for the reduction of CO 2 to CO. Cyclic voltammetry studies and bulk controlled‐potential electrolysis experiments were performed by using a CO 2 ‐saturated acetonitrile solution. The CO 2 reduction, determined by cyclic voltammetry, occurs at approximately −1150 mV versus the normal hydrogen electrode (NHE). Quantitative analysis by GC and IR spectroscopy was used to determine a Faradaic efficiency of approximately 33 % for the formation of CO. Both values of the modified electrode were compared to the performance of the homogenous monomer [Re(5,5′‐bisphenylethynyl‐2,2′‐bipyridyl)(CO) 3 Cl] in acetonitrile. The polymer formation and its properties were studied by using SEM, AFM, and attenuated total reflectance (ATR) FTIR and UV/Vis spectroscopy.