Green synthesis of CdS Quantum dots for photocatalytic and anti-corrosive applications in aqueous media

Inorganic pollutants are the leading cause of water pollution, which harms human health and the environment. The most highly efficient nanoparticles with enhanced photocatalytic activity are semiconductor quantum dots (QDs). The heterogeneous photocatalysis using UV radiation on quantum dots is a fascinating technique for treating polluted sewage with a naturally available plant-based product. In this study, CdS QDs were synthesized using a facile green synthetic protocol in the presence of Coccinia grandis (CG) and Punica granatum (PG) fruit sap as capping and stabilizing agents. XRD, HR-TEM, FT-IR, UV-DRS, and photoluminescence spectroscopy were used to analyze the synthesized CdS QDs. The photocatalytic degradation activity of CdS quantum dots was performed against anionic and cationic dyes under UV light irradiation. The results revealed that PG-capped CdS QDs have the best photocatalytic activity compared to CG-capped CdS QDs. Further, the pseudo-first-order model is used to analyze the kinetics studies. Moreover, the electrochemical measurements of pure zinc and CdS QDs coated Zn (Zn/CdS QDs) plate were tested in three electrolytes: sodium chloride, potassium hydroxide, and hydrochloric acid, which demonstrated the corrosion inhibition ability of prepared CdS QDs. The electrochemical impedance spectra, Tafel plot, and in-situ SPM analysis depict the improving corrosion resistance of the Zn metal plate due to the prepared CdS QDs coatings. Based on the results, the prepared CdS QDs by the green method can be a potential candidate in the water purification and corrosion resistance field.