Solar-driven CO 2 reduction catalysed by hybrid supramolecular photocathodes and enhanced by ionic liquids

Photoelectrochemical carbon dioxide reduction (CO 2 ) at ambient temperature and pressure was performed using molecular chromophores and catalyst assemblies on CuGaO 2 -based electrodes in an ionic liquid (IL) organic solution, acting as a CO 2 absorbent and electrolyte. A simple and versatile methodology based on the silanization of the CuGaO 2 electrode followed by electropolymerization provided a series of molecular and supramolecular hybrid photocathodes for solar driven CO 2 reduction. Focusing on the cathodic half reactions, the most promising conditions for the formation of CO 2 reduction products were determined. The results revealed a beneficial effect of the ionic liquid on the conversion of CO 2 to formic acid and suppression of the production of hydrogen. The potentiality of anchoring supramolecular complexes on semiconductor photoelectrocatalysts was demonstrated to boost both carrier transport and catalytic activity with a FE red of up to 81% compared with the obtained FE red of 52% using bare CuGaO 2 with formate as the major product.