Formic acid-modulated construction of YCDs@NNU-36@UiO-66 heterojunction composites for enhanced photocatalytic degradation of tetracycline hydrochloride

Metal-organic frameworks (MOFs) have attracted significant attention due to their excellent catalytic properties; however, the limited light-responsive range of individual MOFs restricts their practical photocatalytic applications. Moreover, constructing dual-MOF-based systems provides an effective strategy for integrating complementary functional units and enhancing catalytic performance. In this study, a dual-MOF structure was constructed through an epitaxial growth strategy, and a novel dual-heterojunction catalyst was fabricated by introducing yellow-emitting carbon dots (YCDs) onto the surface of NNU-36@UiO-66. Under visible-light irradiation, the obtained YCDs@NNU-36@UiO-66 composite exhibited enhanced photocatalytic activity toward the degradation of tetracycline hydrochloride (TCH), achieving an overall degradation efficiency approximately 1.15 times higher than that of pristine NNU-36@UiO-66. Reactive species trapping experiments revealed that hydroxyl radicals (·OH) and superoxide radicals (·O^2–) were the predominant reactive species involved in the photocatalytic process. This work provides new insights into the rational design of stable dual-heterojunction photocatalysts based on MOF composites for environmental remediation applications.