Nano-on-Micro BiOCl _0.6 Br _0.4 /Zn ₃ In ₂ S ₆ Heterostructure with Prolonged Charge Separation and Exposed Bi Active Sites for Efficient CO ₂ Photoreduction

The inefficient dynamics of photogenerated charge carriers and the limited accessibility of active sites remain concurrent challenges for achieving efficient solar-driven CO₂ photoreduction. Herein, a distinct nano-on-micro (NOM) BiOCl_0.6Br_0.4/Zn₃In₂S₆ heterostructure (<i>NOM-BZ</i>) is rationally constructed by precisely anchoring nano-BiOCl_0.6Br_0.4 onto micro-Zn₃In₂S₆ via an <i>in situ</i> seed-growth route. This architecture simultaneously optimizes charge kinetics and surface redox sites, thereby significantly enhancing the CO₂-to-CO conversion performance. In particular, NOM-BZ exhibits a prolonged average charge lifetime of 3102 ps (<i>5-fold higher than pristine</i>) and abundant electron-rich Bi active sites, especially Bi^{(3-<i>x</i>)+} species, which efficiently drive CO₂ reduction. In addition, NOM-BZ facilitates CO₂ adsorption and activation and promotes *COOH intermediate formation by lowering the energy barriers, leading to noteworthy activity and long-term stability. This work highlights a robust NOM-engineered heterostructure capable of concurrently modulating charge dynamics and active-site chemistry, offering a promising paradigm for the rational design of next-generation photocatalysts for CO₂ conversion.