Surface modification of ZIF-67 with conjugated organic molecules for effective enhancement of visible-light photocatalytic activity

Zeolitic Imidazolate Framework-67 (ZIF-67) has garnered significant attention in photocatalysis due to its remarkable visible-light responsiveness. However, its practical application is often hindered by the rapid recombination of electron-hole pairs. In this study, ZIF-67 was modified using selected conjugated organic molecules with distinct skeletal structures and functional groups, including 1,3,6,8-tetra(4-carboxylphenyl)pyrene, 3,3′-diaminobenzidine and benzimidazole, through a simple one-step solvothermal process and three nanocomposites (ZIF-67@BA, ZIF-67@Pyrene and ZIF-67@BIM) were developed. The results demonstrated that all three composites exhibited enhanced electron-hole separation efficiency, reduced bandgap energy, and superior visible-light response characteristics compared to pristine ZIF-67. These conjugated molecules effectively modulated the photocatalytic performance of ZIF-67, with BA demonstrating the most pronounced enhancement owing to its well-defined symmetrical configuration, exceptional conjugation effect, and functional groups. The optimized ZIF-67@BA composite achieved 89.2 % total removal of tetracycline hydrochloride under visible light irradiation, including 35.5 % photocatalytic degradation efficiency, with even higher performance in practical water treatment. The composite also exhibited excellent reusability, stability, and adaptability. Trapping experiments revealed that •O 2 ⁻ and h⁺ served as the primary active species. This study provides an effective strategy for developing ZIF-67-based nanocatalysts while offering new insights for designing other MOF-based photocatalysts with promising potential for organic pollutant removal.