Electrochemical detection and photodegradation of antihistamine promethazine hydrochloride in water using nanostructured Bi₂S₃ catalysts

Promethazine hydrochloride (PMZH) drugs have become critical to human and veterinary health systems in recent years. Improper disposal of their residues merely contaminates environmental samples and food products. Therefore, a rapid detection and efficient treatment of PMZH is highly desired. In this study, a facile and simple method applied to prepared bismuth sulfide (Bi₂S₃) nanostructures with different morphologies such as nanorods, nanoflowers, and nanocorals has been investigated. The structural analyses of the prepared material were characterized. These results support the formation of Bi₂S₃ nanostructures with well-crystalline nature. The fabricated electrode was effectively used for the determination of PMZH drug. Among them, the Bi₂S₃ nanocorals (Bi₂S₃ NCs) showed greater electrochemical detection of PMZH due to their high surface area, mass/ionic transport, and chemical stability. The modified electrode (Bi₂S₃ NCs/GCE) exhibited a sensing dynamic range of 0.049–79.9 μM, a detection limit of 5.9 nM, and an acceptable sensitivity of 3.69 µA µM⁻¹ cm⁻² with excellent cycling stability. It revealed excellent reproducibility, storage stability, and selectivity parameters. Moreover, the proposed PMZH sensor solidifies an excellent platform for its rapid and on-spot exposure without demanding a well-equipped lab arrangement. To verify its possible applications, this method was applied for the quantification of PMZH in real human serum samples. Finally, these nanostructures were further utilized as photocatalysts for the degradation of PMZH in aqueous solutions.