Bismuth sulfide micro flowers decorated nickel foam as a promising electrochemical sensor for quantitative analysis of melamine in bottled milk samples.

Here, we demonstrate hydrothermally grown bismuth sulfide (Bi 2 S 3 ) micro flowers decorated nickel foam (NF) for electrochemical detection of melamine in bottled milk samples. The orthorhombic phase of hydrothermally grown Bi 2 S 3 is confirmed by the detailed characterization of x-ray diffraction and its high surface area micro flowers-like morphology is investigated via field emission scanning electron microscope. Furthermore, the surface chemical oxidation state and binding energy of Bi 2 S 3 /NF micro flowers is analyzed by x-ray photoelectron spectroscopy studies. The sensor exhibits a wide linear range of detection from 10 ng l -1 to 1 mg l -1 and a superior sensitivity of 3.4 mA cm -2 to melamine using differential pulse voltammetry technique, with a lower limit of detection (7.1 ng l -1 ). The as-fabricated sensor is highly selective against interfering species of p-phenylenediamine (PPDA), cyanuric acid (CA), aniline, ascorbic acid, glucose (Glu), and calcium ion (Ca 2+ ). Real-time analysis done in milk by the standard addition method shows an excellent recovery percentage of ̴ 98%. The sensor's electrochemical mechanism studies reveal that the high surface area bismuth sulfide micro flowers surface interacts strongly with melamine molecules through hydrogen bonding and van der Waals forces, resulting in a significant change in the sensor's electrical properties while 3D skeletal Nickel foam as a substrate provides stability, enhances its catalytic activity by providing a more number /of active sites and facilitates rapid electron transfer. The work presented here confirms Bi 2 S 3 /NF as a high-performance electrode that can be used for the detection of other biomolecules used in clinical diagnosis and biomedical research.