Direct Electrochemical Conversion of Carbon Dioxide into Methanol in Water with High Faradaic Efficiency by Mo-Functionalized Electrode

We developed a new electrocatalysts for hybrid homogeneous / heterogeneous conversion of CO2 in water. A Molybdenum-based organometallic compound has been linked by covalent C-C bond to a carbon-cloth electrode surface. This technique allows using the Mo catalyst in water, a solvent in which the catalyst is not soluble, for the direct electrocatalytic conversion of CO2 to methanol. Although the system displays moderate current density (1÷4 mA/cm2), the very high faradaic efficiency of the CO2-to-methanol conversion (65%), the good selectivity (H2 is the only other reduction product), the simply experimental setup and the potential industrial scale-up of the technique makes this approach of great interest. Chronoamperometric measurement carried in water for 21 hours show a stable and constant catalytic performance with no other carbon-reduced products. Spectroelectrochemistry and detailed DFT calculations shed light on the catalytic process, which consists of six protons coupled electron transfer (PCET) steps. We propose the catalytic cycle that converts CO to methanol in which the first step is a PCET localized on the CO coordinated to the metal.