Carbon dots/TiO₂ hybrids for photocatalytic degradation of drugs in the aquatic environment

The occurrence of pharmaceutical residues in water bodies represents a growing environmental and public health concern, as many of these compounds are not fully removed by conventional wastewater treatment technologies. Carbamazepine (CBZ), a widely prescribed antiepileptic drug, is among the most persistent pharmaceuticals detected in aquatic environments and is frequently used as an indicator of treatment inefficiency. This study presents an advanced photocatalytic material designed to enhance the removal of carbamazepine from water by combining mesoporous titanium dioxide (TiO₂) with luminescent and phosphorescent carbon dots (CDs and PhCDs).

Two anatase TiO₂ photocatalysts with distinct porosity and morphology were prepared via solvothermal synthesis and thermal conversion of a titanium-based metal–organic framework, respectively. The materials were modified by impregnation with carbon dots and thoroughly characterised to assess their structural, optical, and surface properties. The photocatalytic performance of the resulting hybrids was evaluated under UV-Vis irradiation using carbamazepine degradation and total organic carbon (TOC) removal as key indicators of treatment efficiency.

The incorporation of carbon dots broadened the light absorption range of TiO₂ toward the visible region, enabling more effective utilisation of solar irradiation. In particular, phosphorescent carbon dots significantly improved photocatalytic performance by prolonging the lifetime of photogenerated charge carriers and reducing electron–hole recombination. As a result, the PhCDs@TiO₂ hybrid achieved faster carbamazepine degradation and higher mineralisation efficiency compared to unmodified TiO₂, even at reduced photocatalyst loadings.

These findings demonstrate the potential of phosphorescent carbon dot-modified TiO₂ as a practical photocatalyst for water treatment applications. The use of low-cost, metal-free carbon dots combined with a well-established TiO₂ platform offers a promising and scalable approach for removing persistent pharmaceutical contaminants in advanced oxidation processes and solar-driven wastewater treatment systems.