High Performance Cuprous Oxide@Graphitic Carbon Nitride/Glassy Carbon Electrode Electrochemical Sensor for Simultaneous and Sensitive Detection of Dopamine and Uric Acid

This study reports an electrochemical sensor for simultaneous detection of dopamine (DA) and uric acid (UA) using a glassy carbon electrode (GCE) modified with a cuprous-oxide graphitic carbon nitride (Cu 2 O@GCN) nanohybrid. The composite was characterized using XPS, FTIR, SEM‐EDX, and XRD. The latter confirmed the incorporation of cuprous-oxide within the GCN matrix. XPS revealed Cu 2p 1 / 2 and Cu 2p 3 / 2 peaks at 952.6 eV and 932.8 eV, indicating copper in + 1-oxidation state. CV showed an electroactive surface area of 0.1025 cm 2 , while EIS exhibited low charge-transfer resistance ( R ct = 320 Ω), demonstrating efficient electron transport. The sensor displayed a wide linear range of 1–750 µM for simultaneous DA and UA detection, with R 2 = 0.998 and 0.997, and low LOD of 0.40 µM (DA) and 0.25 µM (UA). Excellent reproducibility (RSD = 1.35% and 1.55%) and repeatability (RSD = 1.48% and 1.62%) were achieved. Stability tests showed 97% and 94% retention of initial responses after one week. The sensor also exhibited high selectivity against common interferents. Recoveries in human serum yielded 101%–105%, confirming both accuracy and practical applicability. These findings substantiate the Cuprous-oxide@GCN/GCE sensor as a sensitive, reliable, and selective platform for simultaneous electrochemical determination of DA and UA in biological samples.