Application Of ZnO/CNTs Co-modified Carbon Paste Electrode In Detecting Physiologically Active Substances

In recent years, electroanalytical method is the fastest growing discipline, widely used in electrocatalysis, biosensors and other fields with high sensitivity, good selectivity and reproducibility, rapid detection and so on.In this dissertation, ZnO nanoflowers were synthesized by a simple process (ammonia-evaporation-induced), the morphology and crystal structure of the prepared material were characterized by sanning electron microscopy (SEM) and X-ray powder diffraction (XRD) techniques. The ZnO nanoflowers and multi-walled nanotubes were mixed directly with certain proportion for preparing carbon paste electrodes. This new electrode presented an excellent electrocatalytic activity towards the oxidation of dopamine (DA) and ascorbic acid (AA). The separation potentials of the oxidation peak potentials for them were about261mV by cyclic voltammetry (CV) method. The difference is large enough to determine DA and AA individually and simultaneously. Calibration curves in the ranges of5～40μM and20～180μM were obtained for DA and AA. respectively. By differential pulse voltammetry (DPV), the lowest detection limits (S/N=3) were2.8μM and15μM for DA and AA, respectively. The ZnO/CNTs carbon paste electrode showed better electrochemical catalytic effect and it was a novel electrode. This experiment also expanded the actual application of ZnO.The ZnO/CNTs modified paste carbon electrode also showed excellent electrocatalytic activity for the simultaneous determination of hypoxanthine (HX), xanthine (XA) and uric acid (UA). The oxidation peaks of the three compounds were well defined and had the enhanced peak currents. The separation potentials of the oxidation peak potentials for HX-XA and XA-UA were330mV and410mV in CV, respectively. Using differential pulse voltammetry (DPV) method, the calibration curves in the ranges of10～100μM,5～110μM and5～240μM were obtained for HX, XA and UA, respectively. The lowest detection limits (S/N=3) were3μM,1μM and1μM for HX, XA and UA. respectively. The electrode had a certain novelty and expanded the practical applications of ZnO.