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

Abstract

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 FE_red of up to 81% compared with the obtained FE_red of 52% using bare CuGaO₂ with formate as the major product.