Application of a g-C <sub>3</sub> N <sub>4</sub> @nZVI/CNTs Modified Carbon Paste Electrode for Uric Acid Detection in Spiked Urine Samples
Aya A. Mouhamed, Ola G. Hussein, Maria Osama Mekhail, Taher Taha Zaki, Amr M. Mahmoud, Jeffrey G. Bell
Abstract
A carbon paste electrode (CPE) based on a g-C 3 N 4 @nZVI/CNT nanocomposite was fabricated via chemical reduction and subsequently evaluated towards electrochemical detection of uric acid (UA) via differential pulse voltammetry (DPV). During synthesis, graphitic carbon nitride (g-C 3 N 4 ) serves as a durable substrate with extensive surface area promoting the homogeneous distribution of nano zero-valent iron (nZVI) particles. Carbon nanotubes (CNTs) were incorporated into the composite to enhance electrical conductivity and mechanical stability. The subsequent nanocomposite was characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy, confirming the successful integration of g-C 3 N 4 , nZVI, and CNTs with well-dispersed iron nanoparticles on the g-C 3 N 4 matrix. The resulting g-C 3 N 4 @nZVI/CNT-modified CPE demonstrated superior electrochemical sensitivity toward UA as evidenced by a pronounced increase in peak current during DPV analysis compared to bare and individually modified electrodes. Under optimized conditions, the sensor exhibited a linear response of 2.0–100.0 μM and detection limit of 1.7 μM. The electrode maintained high selectivity in the presence of common interferants with good repeatability and long-term operational stability. These findings highlight the synergistic interaction among g-C 3 N 4 , nZVI, and CNTs in boosting electron transfer and catalytic activity, making this composite a promising, cost-effective, and scalable solution for sensitive UA detection in clinical diagnostics and environmental monitoring.