Embedding CdTe@CdS QDs into the C₃N₅ nanosheets with enhanced activity for visible-light-driven photocatalytic degradation of methylene blue and tetracycline

The enhanced visible-light-driven photocatalyst is crucial in fabricating the composites, promoting light harvesting in the visible range, and producing more reactive oxygen species (ROS). In this research, two approaches were studied for expanding light trapping and reducing charge recombination. Firstly, the core–shell structure of CdTe@CdS quantum dots (QDs) was synthesized with unique optoelectronic properties and the ability for light absorption in the visible range. Then, these QDs were loaded in the structure of fabricated C₃N₅ nanosheets with a nitrogen-rich carbon nitride structure. The photocatalytic activity of the CdTe@CdS − C₃N₅ nanocomposite was assessed for the degradation of organic pollutants from water. Significant enhancement in specific surface area from 3.35 m²/g for bulk C₃N₅ to 34.96 m²/g for C₃N₅ nanosheets confirmed successful exfoliation of the C₃N₅. The photocatalytic activity of the synthesized nanocomposite was investigated for the degradation of Methylene blue (MB) and Tetracycline (TC) as model molecules. Influential factors such as catalyst amount, pH, scavengers, dye concentration, and catalyst reuse were studied. The maximum degradation efficiency of 99.7 % and 84 % was obtained for MB and TC with an initial concentration of 10 mg/L in the presence of CdTe@CdS-C₃N₅ 0.06 wt% nanocomposite within 60 min of reaction time under xenon light. Also, the stability of the synthesized photocatalyst was high up to 8 cycles. The photocatalytic reaction follows pseudo-first-order kinetic, in which the hydroxyl radicals play an influential role in the degradation process.