Efficient photocatalytic chlorine production on bismuth oxychloride in chloride solution

[Display omitted] •This work provides a novel photochemical route for Cl2 production.•By virtue of the efficient photocatalytic Cl2 production, this route shows the application potential in CH4 functionalization and production of disinfectant.•The Cl− extraction from and insertion into the open structure of BiOCl contribute to the excellent performance.•Photocatalysis is also extended to Br2 production, confirming the universality of this technique for halide ion oxidation. Chlorine (Cl2) one of the most important base chemicals, is manufactured conventionally by electrolysis of saturated NaCl solution in chlor-alkali process which suffers from high power consumption and economic constraints. Herein, we report the novel light-driven chlorine evolution reaction (CER) in synthetic seawater using bismuth oxychloride (BiOCl) photocatalyst, providing an economical and convenient route for Cl2 production. A superior Cl2 production rate of 19.6 μmol h−1 (about 27.79 mg L−1 h−1) is achieved, which is sufficient for methane functionalization and production of chlorine-based disinfectant. Experimental and theoretical studies reveal that the Cl− extraction from and insertion into the open structure of BiOCl contribute to the excellent performance. The lattice Cl− could be self-oxidized to form Cl2, while Cl− in solution would fill the lattice Cl− vacancies, making CER continue. This technique is also applicable to Br2 production. This work opens up prospects for halogen production based on solar energy.