Chirality-Regulated Spin-Polarization of Perovskite Nanoplates for Photocatalytic CO₂ Reduction Reaction

Manipulating spin polarizations of photoexcited electrons has been found to play a vital role in enhancing photocatalytic CO₂ conversion by suppressing carrier recombination. In this work, photocatalytic CO₂ reduction conversion efficiencies are significantly enhanced by chirality-regulated spin-polarization of CsPbBr₃ perovskite nanocrystals. We propose the chirality-regulated perovskite thin films by incorporating chiral molecules (MBA:Br) into all-inorganic CsPbBr₃ perovskite nanoplates (NPLs), resulting in (R)- and (S)-2D Ruddlesden-Popper perovskite (RPP)/NPL hybrids. In this configuration, the chiral 2D RPP perovskites offer a significant chiroptical response that promotes the generation of spin-polarized electrons. The chirality-regulated spin-polarization of 2D RPP/NPLs hybrid perovskite thin films has significantly suppressed charge carrier recombination rates, thereby enhancing the efficiency of photocatalytic CO₂ reduction. By harnessing the synergistic effects of induced chirality and the application of an external magnetic field of 0.3 T, the photocatalytic CO₂ reduction efficiencies of the chiral perovskites can be enhanced to be five times that of the pristine CsPbBr₃ perovskite NPLs. The interplay between structure, chirality, spin polarization, and carrier dynamics associated with the enhanced photocatalytic activity of perovskite nanocrystals was systematically analyzed using grazing-incidence wide-angle X-ray scattering (GIWAXS) spectroscopy, magnetic circular dichroism (MCD) spectroscopy, and time-resolved photoluminescence (PL) techniques. Our results pave the way for the manipulation of spin-polarized electrons through chirality-regulated perovskite nanocrystals, significantly enhancing photocatalytic CO₂ reduction efficiencies and highlighting their strong potential for future solar-to-fuel conversion applications.