ABSTRACT
The present study used CeO2-Co3O4 quantum dots@porous carbon/multiwalled carbon nanotube (CeO2-Co3O4 QDs@PC/MWCNT/GE) composites to modify graphite electrodes to fabricate high-sensitivity electrochemical sensors to detect the presence of oxytetracycline (OTC). The quantum dots were made from waste sugarcane bagasse. The electrochemical analysis demonstrated the superior electrochemical performance of CeO2-Co3O4 QDs@PC/MWCNT/GE, with a peak current density of 1.276 mA/cm2. Electrochemical impedance spectroscopy (EIS) revealed lower impedance values for CeO2-Co3O4 QDs@PC/MWCNT/GE compared to other electrodes, indicating enhanced conductivity. The modified electrode exhibited an enlarged electrochemically active area, with values of 0.602 cm2, almost seven times that of the bare graphite electrode (0.079 cm2). The results showed that the CeO2-Co3O4 QDs@PC/MWCNT/GE had excellent performance for OTC detection, and its linear calibration range was 1.007 × 10-8 to 2.04 × 10-7 M (i.e., 0.005-0.1 ppm) and 1.007 × 10-6 to 1.209 × 10-4 M (i.e., 0.5-60 ppm). The limit of detection and limit of quantification were 1.23 nM (0.61 ppb) and 4.09 nM (2.03 ppb) (S/N = 3), respectively. The electrode demonstrated long-term stability for up to 7 weeks. This method provides a new way to prepare electrochemical sensors for OTC detection.
