Electrochemical quantification of dopamine using a nanocomposite of silver nanoparticles-potassium modified graphitic carbon nitride (Ag/K-g-CN).

Herein, a selective and sensitive electrochemical sensor based on silver nanoparticles-potassium modified graphitic carbon nitride (Ag/K-g-CN) was developed. The nanocomposite was synthesised via a combined thermal and solvothermal method for the dopamine (DA) detection. To create bulk CN, melamine was thermally polymerised at 550 °C. Subsequently, solvothermal-assisted exfoliation yielded g-CN nanosheets. Next, the porous g-CN was modified with KOH by grinding, dispersing it in an ethanol-water mixture, and calcined it at 300 °C to create K-modified g-CN. Ultrasonication was used to disperse Ag NPs evenly within K-g-CN, yielding a homogeneous Ag/K-g-CN nanocomposite. The Ag/K-g-CN-modified electrode exhibited significant electrochemical responses, demonstrating its successful attachment to the electrode surface. High-resolution transmission electron microscopy (HR-TEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were used to investigate the structural and morphological features. The sensor's performance was evaluated using linear sweep voltammetry (LSV) and cyclic voltammetry (CV), with a broad linear range of 0-500 μM, a low detection limit of 0.629 μM, and a sensitivity of 0.432 μA μM-1 cm-2 for DA. Practical application was demonstrated using spiked recovery studies in 100-fold diluted human serum samples, yielding recoveries of 99-100%, validating the reliability of the proposed sensor.