Ultrathin Two-Dimensional BiOCl with Oxygen Vacancies Anchored in Three-Dimensional Porous g‑C₃N₄ to Construct a Hierarchical Z‑Scheme Heterojunction for the Photocatalytic Degradation of NO

In this paper, we successfully designed a hierarchical Z-scheme heterojunction with adjustable oxygen vacancy concentration, in which ultrathin two-dimensional BiOCl nanosheets with oxygen vacancies (OVs) were anchored on porous three-dimensional g-C₃N₄ spheres to obtain BiOCl-OVs/g-C₃N₄ spherical composites. The synergistic effect of oxygen vacancies and Z-scheme heterojunctions on composite BiOCl-OVs/g-C₃N₄ spheres increases the transmission rate of photogenerated carriers and inhibits the recombination of electrons and holes. Meanwhile, OVs are not only used as electronic media but also as the recombination and storage centers of photogenerated carriers. The porous structure of the three-dimensional spheres provides a larger specific surface area and an open pore structure, which facilitates the circulation and transfer of pollutant gases. The above characteristics give BiOCl-OVs/g-C₃N₄ spheres excellent performance in degrading NO under visible light, at rates of up to 66.5%. In addition, cycle experiments and X-ray diffraction (XRD) indicate that the material also has excellent stability and recyclability.