Tea-derived carbon quantum dot-modified PCN-415-NH2 nanocomposite as a bifunctional adsorbent–photocatalyst for efficient wastewater treatment under visible light

Industrial dye contamination requires efficient and sustainable wastewater treatment technologies. Herein, we report, for the first time, the integration of black tea-derived carbon quantum dots (CQDs) into the Ti–Zr-based metal–organic framework PCN-415-NH 2 . The resulting composite acted as an efficient bifunctional adsorbent–photocatalyst for the removal of rhodamine B (RhB) under visible light. CQDs incorporation enhanced the photocatalytic performance while preserving the crystalline structure and porosity of the MOF. Notably, CQDs loading did not reduce the specific surface area of PCN-415-NH 2 , which is often observed in CQDs/MOF composites. The nanocomposite achieved 94% RhB degradation within 45 min, significantly outperforming pristine PCN-415-NH 2 and CQDs. In addition, it showed a maximum adsorption capacity of 57.2 mg/g and followed the Freundlich isotherm and pseudo-second-order kinetic models. The enhanced performance was attributed to improved charge separation and synergistic adsorption–photocatalysis effects. The intermediate products formed during the photodegradation of RhB were identified by GC–MS analysis. These findings demonstrate that tea-derived CQDs-modified PCN-415-NH 2 is a promising visible-light-responsive material for efficient wastewater treatment.