Combining more than two metal–organic frameworks (MOFs) with different structures is an intelligent strategy for the architecture of hybrid MOFs. Herein, well-organized UiO-66(Zr)-on-MIL-125(Ti)-NH2 growth with g-C3N4 nanosheets was developed for the Gomberg–Buchmann–Hey reaction under visible light irradiation (λ > 420 nm). First, UiO-66(Zr) micropores as host MOFs were fabricated by a solvothermal method. Subsequently, MIL-125(Ti)-NH2 crystals and g-C3N4 nanosheets were grown inside UiO-66(Zr) to obtain a new type of the dual Z-scheme Zr-MOF/Ti-MOF/g-C3N4 heterojunction photocatalyst. Under visible light irradiation, this dual Z-scheme heterojunction acts as a highly efficient photocatalyst for forming C–C bonds via diazonium salts, which can compete with the best photocatalyst systems. The findings indicated that the presence of Zr and Ti metals in MOF-on-MOF and g-C3N4 nanosheets could significantly increase the separation of photogenerated electron–hole pairs and then enhance the photocatalytic performance. The present study not only provides new insights into the architecture of MOFs on other MOFs but also develops Z-scheme heterojunction materials for coupling reactions and other organic reactions under visible light irradiation.
