A Novel Non-Fullerene D-A Interface with Two Asymmetrical Electron Acceptors Facilitates Charge and Energy Transfer for Effective Carbon Dioxide Reduction.

ABSTRACT

Converting carbon dioxide (CO2 ) into high-value chemicals using solar energy remains a formidable challenge. In this study, the CSC@PM6IDT6CN-MIDT8CN-M non-fullerene small-molecule organic semiconductor is designed with highly efficient electron donor-acceptor (D-A) interface for photocatalytic reduction of CO2 . Atomic Force Microscope and Transmission Electron Microscope images confirmed the formation of an interpenetrating fibrillar network after combination of donor and acceptor. The CO yield from the CSC@PM6IDT6CN-MIDT8CN-M reached 1346 µmol g-1  h-1 , surpassing those of numerous reported inorganic photocatalysts. The D-A structure effectively facilitated charge separation to enable electrons transfer from the PM6 to IDT6CN-MIDT8CN-M. Meanwhile, attributing to the dipole moments of the strong intermolecular interactions between IDT6CN-M and IDT8CN-M, the intermolecular forces are enhanced, and laminar stacking and π-π stacking are strengthened, thereby reinforcing energy transfer between acceptor molecules and significantly enhanced charge separation. Moreover, the strong internal electric field in the D-A interface enhanced the excited state lifetime of PM6IDT6CN-MIDT8CN-M. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis demonstrated that carboxylate (COOH*) is the predominant intermediate during CO2 reduction, and possible pathways of CO2 reduction to CO are deduced. This study presents a novel approach for designing materials with D-A interface to achieve high photocatalytic activity.