Chirality Engineering of BiOCl/BiOBr Hybrid Photocatalysts for Polarized-Photon-Selective Chiral Catalysis

The inability to achieve the selective recognition of specific chiral molecules or polarized photons has significantly hindered the application of conventional photocatalysts in asymmetric synthesis. To address this challenge, we have designed and synthesized discrete chiral BiOCl/BiOBr hybrid semiconductors with multilevel chirality, ranging from atomic-scale lattice distortion to microscale fan-blade-like plates and geometrically chiral superstructures. These hierarchically chiral semiconductors enable the polarization-dependent photodegradation of chiral tetracycline (TC) molecules. Under dark conditions, the L-BiOCl/BiOBr hybrids exhibit stronger adsorption for TC than their D counterparts, which can be attributed to conformational energy differences. Strikingly, under right-, left-, and linearly polarized light (RCP, LCP, and LP), the L-hybrids achieve TC degradation rates that are 19.3, 12.0, and 3.3 times higher, respectively, than those of the achiral reference. A similar polarization-dependent trend is observed for the D-hybrids. Combined DFT simulations and circularly polarized photocurrent measurements confirm that this photon-selective asymmetric catalysis originates from the synergistic interplay of an atomic-level chiral structure, polarized-light response, and spin-polarized charge separation. Moreover, L-BiOBC_0.33 and D-BiOBC_0.33 exhibit the same polarized photon-selective chiral catalytic behavior toward the degradation of chiral ofloxacin. This work establishes a paradigm for designing efficient chiral photocatalysts with hierarchical chirality, providing a route for tailoring nanomaterials for selective light-matter interactions and spin-polarized catalysis, with potential applications in chiral synthesis and chiral nanophotonics.