Asymmetric Dipole-Field Engineering in Chiral Mesostructures for Efficient Photocatalytic N2 Reduction.

Chiral mesostructures with helical surfaces hold significant potential as spatially confined nanoreactors for solar-driven nitrogen (N2) photoconversion. Nevertheless, simultaneously enhancing polarized charge separation, improving N2 capture, and optimizing catalytic efficiency remains a critical challenge in advancing the performance of such nanoreactors. Herein, we successfully constructed a spatially confined Fe-doped BiOBr chiral mesostructure by designing acid-base Lewis coordination to enable multidentate coordination between Bi3+ and sorbitol. This precisely engineered helical surface-confined architecture not only elucidates the influence of confined surface geometry on N2 adsorption behavior but also demonstrates that the asymmetric dipole field enhances anisotropic charge separation during photocatalysis, leading to a significantly improved photocatalytic NH3 production performance. Notably, the optimized chiral Fe-BiOBr confined reactor exhibits an approximately 8-fold enhancement in photoactivity compared to pristine BiOBr under simulated solar irradiation. This work establishes a paradigm for the design of chiral mesostructured photocatalysts, wherein the helical surface architecture serves as an intrinsic component of the confined reactor, enabling effective decoupling of the asymmetric dipole field effect from confinement catalysis. This strategy provides a scalable pathway toward the development of efficient solar-to-chemical conversion systems.