Donor/Acceptor Bulk Heterojunctions for Efficient Visible-Light CO2 Reduction to CO.

High-performance organic photovoltaic (OPV) materials, characterized by tunable energy levels, broad light absorption, and facile processability, show considerable potential for photocatalytic applications. However, their inherent susceptibility to oxygen and moisture limits their practical use under complex reaction conditions. Here, organic photocatalyst/adsorbent systems based on donor/acceptor (D/A) bulk heterojunctions, particularly PM6:SY1 and PM6:Y6 supported on biochar (BC), were constructed to bridge the different interfacial requirements of organic photocatalysis at the gas-liquid-solid interface and organic photovoltaics at the solid-solid interface. The D/A bulk heterojunctions enhance light harvesting and facilitate exciton dissociation, enabling a CO production rate of 1.68 mmol g- 1 h- 1 and a cumulative CO yield of 10.1 mmol g- 1 over 6 h, while maintaining stable photocatalytic performance over 10 consecutive cycles. Density functional theory (DFT) calculations further provide molecular-level insights into intermolecular interactions and energetic characteristics relevant to charge separation. These results demonstrate the potential of D/A bulk-heterojunction organic photovoltaic materials for photocatalytic CO2 reduction and improved operational stability under the tested conditions.