Bidirectional host-guest interactions promote selective photocatalytic CO2 reduction coupled with alcohol oxidation in aqueous solution

Existing artificial photosynthesis systems often underperform due to challenges in water oxidation and extensive photogenerated carrier transfer. Herein, we demonstrate that β-cyclodextrin-decorated CdS nanocrystals (CdS-CD) can simultaneously anchor cobalt tetraphenyl porphyrin (CoTPP) catalysts and alcohol reductants onto CdS surfaces through bidirectional host-guest interactions between β-CD and CoTPP/alcohol. This configuration ensures swift electron transfer from CdS to β-CD bonded CoTPP, facilitating CO2 reduction to HCOOH. Results showcase a remarkable yield of 1610 μmol g−1 h−1 and a 96.5% selectivity. Meanwhile, photogenerated holes in CdS are efficiently neutralized by β-CD bonded furfuryl alcohol, achieving a furfural yield of 1567 μmol g−1 h−1 and > 99% selectivity. In contrast, the discrete CoTPP-CdS system achieved a HCOOH yield of only 306 μmol g−1 h−1 and a poor HCOOH selectivity of 46.4%. It was also observed that the CoTPP@CdS-CD system maintained high CO2-to-HCOOH conversion rates when using other alcohols as reductants.