Solar-driven CO2 reduction catalysed by hybrid supramolecular photocathodes and enhanced by ionic liquids

Photoelectrochemical carbon dioxide reduction (CO2) at ambient temperature and pressure was performed using molecular chromophores and catalyst assemblies on CuGaO2-based electrodes in an ionic liquid (IL) organic solution, acting as a CO2 absorbent and electrolyte. A simple and versatile methodology based on the silanization of the CuGaO2 electrode followed by electropolymerization provided a series of molecular and supramolecular hybrid photocathodes for solar driven CO2 reduction. Focusing on the cathodic half reactions, the most promising conditions for the formation of CO2 reduction products were determined. The results revealed a beneficial effect of the ionic liquid on the conversion of CO2 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 FEred of up to 81% compared with the obtained FEred of 52% using bare CuGaO2 with formate as the major product.

Automated summary

Photoelectrochemical carbon dioxide reduction was successfully performed at ambient temperature and pressure using molecular chromophores and catalyst assemblies on CuGaO2-based electrodes in an ionic liquid organic solution. A series of molecular and supramolecular hybrid photocathodes were prepared by a simple and versatile methodology. The most promising conditions for CO2 reduction were determined and the results showed that the presence of the ionic liquid enhanced the conversion of CO2 to formic acid while suppressing hydrogen production. Anchoring supramolecular complexes on semiconductor photoelectrocatalysts boosted both carrier transport and catalytic activity, achieving a high faradaic efficiency of up to 81%.