Functionalization of Carbon Nanotubes with Nickel Cyclam for the Electrochemical Reduction of CO₂

The exploitation of molecular catalysts for CO₂ electrolysis requires their immobilization on the cathode of the electrolyzer. As an illustration of this approach, a Ni-cyclam complex with a cyclam derivative functionalized with a pyrene moiety is synthesized, found to be a selective catalyst for CO₂ electroreduction to CO, and immobilized on a carbon nanotube-coated gas diffusion electrode by using a noncovalent binding strategy. The as-prepared electrode is efficient, selective, and robust for electrocatalytic reduction of CO₂ to CO. Very high turnover numbers (ca. 61460) and turnover frequencies (ca. 4.27 s⁻¹) are enabled by the novel electrode material in organic solvent-water mixtures saturated with CO₂. This material provides an interesting platform for further improvement.