Simultaneous Electrosynthesis of Syngas and an Aldehyde from CO₂ and an Alcohol by Molecular Electrocatalysis

A tandem cell for artificial photosynthesis with CO2 and water as the oxidants and an organic alcohol as the reductant is described. The use of molecular catalysts with high activity and selectivity, in an appropriate cell configuration, leads to electrochemical reduction of CO2 and water to CO and H2 (syngas) in tandem with benzyl alcohol oxidation to benzaldehyde. A faradaic efficiency (FE) of ∼70% for the formation of benzaldehyde was obtained with simultaneous syngas generation with varying ratios of H2 and CO at the cathode. The maximum energy efficiency obtained for the electrochemical cell was 17.6%.