Homogeneous CO₂ Reduction by Ni(cyclam) at a Glassy Carbon Electrode

The homogeneous CO₂ reduction activity of several nickel cyclam complexes was examined by cyclic voltammetry and controlled potential electrolysis. CO production with high efficiency from unsubstituted Ni­(cyclam) was verified, while the activity was found to be attenuated with methyl substitution of the amines on the cyclam ring. Reactivity with CO₂ was also probed using density functional theory (DFT) calculations. The relative CO₂ binding energies to the Ni^I state obtained from DFT were found to match well with the experimental results and shed light on the possible importance of the isomeric form of Ni­(cyclam) in determining the catalytic activity.