Synthesis an‎d Characterization of CuO/PANI/Graphite Rod Nanocomposite an‎d Investigation of Its Application as an Electrochemical Nitrate Sensor

2/28/2027 12:00:00 AM

Nitrate contamination of water resources has raised concerns regarding public health an‎d the environment, highlighting the need for monitoring this contamination using highly sensitive an‎d low-cost sensors. This study presents the synthesis an‎d characterization of a PANI/CuO/Graphite nanocomposite for the electrochemical sensing of nitrate ions in aqueous media. The sensor was obtained through a two-step electrochemical loading on a graphite rod substrate. First, electrochemical polymerization of polyaniline created a conductive nanofiber matrix. Then, deposition of copper oxide nanoparticles was performed by multi-step amperometry from a CuSO₄/(NH₄)₂SO₄ copper bath. Four electrode configurations — bare graphite rod, PANI/Graphite, CuO/Graphite, an‎d PANI/CuO/Graphite — were compared using cyclic voltammetry, electrochemical impedance spectroscopy, an‎d linear sweep voltammetry to eva‎luate the synergistic contribution of each component. The composite morphology was confirmed by SEM/EDX imaging, showing that copper oxide nanoparticles were distributed throughout a polyaniline nanofiber network. FTIR spectroscopy also confirmed the presence of polyaniline in the emeraldine salt form alongside Cu–O vibrational modes. The PANI/CuO/Graphite composite electrode demonstrated the best nitrate sensing performance, achieving a sensitivity of 231 µA/mM, a linear detection range of 0.16–7.61 mM (R² = 0.9995), an‎d a detection limit of 160 µM. The optimal electrolyte was 0.1 M H₂SO₄ (pH 1), consistent with the proton-dependent nitrate reduction mechanism. The sensor exhibited excellent repeatability (RSD = 1.84%, n = 10) an‎d acceptable short-term operational stability (87.9% current retention after 30 consecutive scans over approximately 4 hours). The proposed sensor offers a simple, low-cost approach for nitrate detection with a working range that encompasses the WHO drinking water guideline for nitrate, demonstrating its suitability for environmental water quality monitoring applications.

حسگر الكتروشيميايي , حسگر نيترات , مس اكسيد , پلي آنيلين , ميله گرافيت , ولتامتري روبش خطي

electrochemical sensor , nitrate sensor , copper oxide , polyaniline , graphite rod , linear sweep voltammetry

seyed saeed mosavi

Dr. Mahboubeh rabbani